ROAD CONDITION ASSESSMENT OF DHAKA-SYLHET ROAD

FROM 15 KM TO 25 KM AND REHABILITATION MEASURES FOR

STRENGTHENING THE PAVEMENT

ISRAR AHMAD

DEPARTMENT OF CIVIL ENGINEERING

DHAKA UNIVERSITY OF ENGINEERING AND TECHNOLOGY, GAZIPUR

OCTOBER, 2009

ROAD CONDITION ASSESSMENT OF DHAKA-SYLHET ROAD

FROM 15 KM TO 25 KM AND REHABILITATION MEASURES

FOR STRENGTHENING THE PAVEMENT

A project thesis

by

ISRAR AHMAD

Submitted to the Department of Civil Engineering

Dhaka University of Engineering and Technology, Gazipur

in partial fulfillment of the degree of

MASTER OF ENGINEEING IN CIVIL ENGINEERING

OCTOBER, 2009

iii

CANDIDATE’S DECLERATION

It is hereby declared that this project or any part of it has not been submitted elsewhere for

the award of any degree or diploma.

Signature of the Candidate

(Israr Ahmad)

iv

The project thesis titled “Road Condition Assessment of Dhaka-Sylhet Road from 15 km

to 25 km and rehabilitation measures for strengthening the pavement” submitted by Israr

Ahmad, Student No. 072111 (P), Session 2007-2008 has been accepted as satisfactory in

partial fulfillment of the requirements for the degree of Master of in Civil Engineering on

October 15, 2009.

BOARD OF EXAMINERS

Dr. Md. Showkat Osman : Chairman

Professor and Head,

Department of Civil Engineering

DUET, Gazipur

Mr. Md. Nuruzzaman : Member

Professor, (Supervisor)

Department of Civil Engineering

DUET, Gazipur

Dr. Ganesh Chandra Saha : Member

Professor,

Department of Civil Engineering

DUET, Gazipur

Dr. Md. Kamal Hossain : Member

Associate Professor,

Department of Civil Engineering

DUET, Gazipur

Dr. Md. Mazharul Hoque : Member (External)

Professor,

Department of Civil Engineering

BUET, Dhaka

v

ACKNOWLEDGMENT

The author would like to express his sincere gratitude to his supervisor Professor Mr. Md.

Nuruzzaman, Department of Civil Engineering, DUET, Gazipur for his valuable advice and

guidance throughout the research work. The author is also grateful to his Member Assistant

Professor Dr. Md. Kamal Hossain, Department of Civil Engineering, DUET, Gazipur who

provided him with information, comments, corrections and criticisms pertaining to the

preparation of this thesis. Appreciation and thanks are also extended to Associated Professor,

Dr. Atiqul Islam of Civil Engineering Department for the valuable advises, suggestions and

support in selection of courses and other related matters of M. Engineering Programme.

He is thankful to Professor Showkat Osman, Head, Department of Civil Engineering, Professor

M. A. Rashid, Dean Faculty of Civil Engineering and Professor BC Basak Ex. Dean Faculty of

Civil Engineering for showing special care and attention in all matters and helping him in

timely completion of post graduate study.

He would also like to thank Dr. Ganesh Chandra Saha, Professor, Department of Civil

Engineering, DUET, Gazipur who helped the author in various ways during this study.

He would also like to thank all other faculty members of DUET for their valuable advice and

encouragement to perform this research.

He would also like to thank to Mr. Anisur Rahman, the Managing Director of DevConsultants

Limited, Project Engineers Mr. Atahar Ali, Mr. Shamsul Arefin and Mr. Jahir Uddin Mahmood

for their constant support and encouragement.

Finally, the author would like to thank his beloved parents, wife, sons, daughter in law and

family members for their constant support and encouragement. Without their support, this

work would never have been completed.

vi

ABSTRACT

This study aims at assessing the road condition in general of roads both National and Regional

Highways of Bangladesh and to recommend measures for rehabilitation or reconstruction

based on the findings on a sample road section at Dhaka-Sylhet National Highway (N-2) for 10

km stretch (Ch. 15+000 km to 25+000 km). This study was carried out to evaluate the

pavement surface conditions and identified possible causes and suggested maintenance

measures of those defects. Three case studies were selected for overlay design. The case

studies were selected from textbooks and journals.

Cracking of asphalt concrete wearing course at many location occurred over the 10 km road

section, particularly in the both sides of centre line of carriage way. Detail survey was carried

out and measured the cracking range. Based on the cracking range percentage the overlay

thickness was found to be 25 mm on the stretch from Ch.15+000 km to 16+000 km, Ch.

20+000 km to 21+000 km and Ch.24+000 km to 25+000 km. Benkelman Beam test was

carried out and deflection value was observed more than 1 mm in stretch of Ch.15+000 km to

16+000 km and Ch.21+000 km to 23+000 km. Low Benkelman deflection and less rut depth

measurement have been recorded and indicating relatively strong foundation in the road

section. Based on the deflection value the overlay thickness was designed 25 mm. The results

show that the thickness of overlay calculated based on deflection value and calculated

percentage cracks range finds 25 mm for both the above mentioned cases. Traffic count survey

was carried out and compared with last year traffic count and found 10% traffic growth.

Asphalt Institute developed a design charts and based on these charts overlay on the full stretch

was designed. The thickness of overlay was designed 50 mm based on traffic data, growth rate

of traffic and deflection value. The result of this study showed that there was deficiency in the

existing pavement structure for heavily loaded trucks at present on the road which further

deteriorate the 10 km stretch. It is essential to provide a surface course of 50 mm immediately

after a thorough repair of the distresses in the existing pavement before placing the overlay.

The life expectancy of 10 km stretch would be 5 years.

vii

TABLE OF CONTENTS

Declaration iii

Approval iv

Acknowledgement v

Abstract vi

Table of Contents vii

List of Tables ix

List of Figures x

Notation xii

CHAPTER 1 INTRODUCTION 1

1.1 General 1

1.2 Objectives of the Study 1

1.3 Scope and Approach of Study 2

1.4 Organization of Thesis 2

CHAPTER 2 LITERATURE REVIEW 3

2.1 General 3

2.2 Types of Surface Distresses 3

2.2.1 Wheelpath cracking asphalt surfacing 4

2.2.2 Non wheelpath cracking asphalt surfacing 6

2.2.3 Longitudinal Cracking 6

2.2.4 Transverse Cracking 6

2.2.5 Block Cracking 7

2.2.6 Crocodile Cracking 7

2.2.7 Parabolic Cracks 7

2.2.8 Potholes 8

2.2.9 Delamination 9

2.2.10 Depression 9

2.2.11 Pavement Rutting 9

2.2.12 Raveling 10

2.2.13 Broken Edge 10

Page No.

viii

2.3 Failure in Asphalt Pavements and Control of Such Failure 11

2.4 Benkelman Beam Deflection 19

2.5 Summary Discussion 19

CHAPTER 3 RESEARCH METHODOLOGY AND DATA COLLECTION 20

3.1 General 20

3.2 Study Area 20

3.3 Methodology of Benkelman Beam Test 20

3.3.1 Benkelman Beam Testing 22

3.4 Methodology for Traffic Studies 30

3.4.1 Survey Technique 32

3.4.2 Video Traffic Count 33

3.5 Methodology of Measuring of Surface Distresses of 36

Bituminous Surface

CHAPTER 4 RESULTS AND DISCUSSION 42

4.1 Introduction 42

4.2 Collection of Core Samples 42

4.3 Flow Charts 44

4.4 Calculation for Design of Overlay 48

4.5 Pavement Condition Assessment 54

4.6 Field Observations and Photographs 59

4.7 Summary 62

CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 63

5.1 Conclusions 63

5.2 Recommendations 64

REFERENCES 65

APPENDICES

App. A Details of Measurement of Deflection of Pavement

Checked by Benkelman Beam Test 67

App. B Road Condition Survey 75

App. C Calculation Details 85

App. D Hourly Traffic Volume Summary Sheet 86

Page No.

ix

LIST OF TABLES

Table No. Description

2.1 Failure in asphalt pavement and control of such failure 11

3.1 Details of vehicle suitable for test 25

3.2 Classify the degreed of cracking at test point 26

3.3 Condition of road and score of rating 38

4.1 Test results of cores 43

4.2 Allowable deflection as per most research project R-6 48

4.3 Initial traffic number adjustment factors 51

4.4 Maintenance and rehabilitation treatments and assumptions used in HDM 52

4.5 Compounds maintenance standards for national corridor roads 55

4.6 Cracking range percentage 55

4.7 Qualitative descriptors of IRI values 57

5.1 Determined overlay based on cracking range percentage 63

5.2 Design overlay based on deflection value 63

5.3 Design overlay based on traffic data 64

Page No.

x

LIST OF FIGURES

Figure No. Description

2.1 Cracking in asphalt surfacing at Ch. 22+000 km 4

2.2 View of Pothole at Ch.16+050 km 8

2.3 View of Broken edge at Ch. 15+100 km 10

3.1 Location Map 21

3.2 Picture shows Vehicle Loaded with Bricks 24

3.3 Measuring the air pressure of tyre 24

3.4 Preparation of Benkelman beam test is in progress 25

3.5 Benkelman Beam 27

3.6 Typical Cross Section 31

3.7 Video Traffic Survey is in Progress 32

3.8 Hourly volume of heavy truck and all other motorized vehicles on 34

one lane from Katchpur to Tarabo

3.9 Percentage of trucks and other motorized vehicles 35

3.10 Picture shows surface distresses at Ch. 17+100 km 39

3.11 Picture shows surface distresses at Ch. 18+100 km 40

3.12 Picture shows surface distresses at Ch. 20+100 km 41

3.13 Picture shows surface distresses at Ch. 15+100 km 41

4.1 Picture shows four sample of cores collected from side (15+100 to 17+200) 42

4.2 Initial deterioration longitudinal cracking in asphalt surfacing 45

4.3 Initial deterioration Transverse cracking in asphalt surfacing 46

4.4 Road pavement evaluation and rehabilitation procedure 47

4.5 Asphalt concrete overlay thickness required to reduce pavement

deflection from a measured to a design deflection value. 49

(From The Asphalt Institute)

4.6 Traffic analysis Chart (From The Asphalt Institute) 50

4.7 Showing evaluated deflection value 58

4.8 Picture shows the failure occurred in the centre of the pavement at 59

Ch.15+300 km

4.9 Minor single longitudinal cracks in the wheel path has begins at 60

Ch. 16+100 km

Page No.

xi

4.10 Picture shows the failure occurred in the centre of the pavement at 60

Ch. 17+300 km

4.11 Picture shows the failure occurred in the centre of the pavement as 61

well as at the pavement edge at Ch. 18+600 km

4.12 Picture shows the failure occurred in the centre of the pavement 61

as well as at the pavement edge. The failure also occurred around the

round about at Ch. 24+200 km

4.13 Picture shows the failure occurred in the centre of the pavement 62

as well as at the pavement edge. The failure also occurred around the

round about at Ch. 24+200 km

Page No.

xii

NOTATIONS

Symbols and

Abbreviation Description and Meaning

ITN Initial Traffic Number

DTN Design Traffic Number

CBR California Bearing Ratio

DBST Double Bituminous Surface Treatment

TRRL Transport and Road Research Laboratory (UK)

TRL Transport Research Laboratory (UK)

MT Motorized

NMT Non Motorized

RHD Roads and Highways Department Bangladesh

AADT Annual Average Daily Traffic

HDM Highway Development and Management

IRI International Roughness Index

h Thickness of the overlay

∆0 Characteristics deflection

∆ Allowable deflection

x Mean

n Number of measurement of deflection

Standard deviation

1

CHAPTER 1

INTRODUCTION

1.1 GENERAL

Roads and Highways Department (RHD) is responsible for the main road network in

Bangladesh. Dhaka-Sylhet Highway is the most important corridor and National Highway of

Bangladesh Road network. The country’s road network is significantly under developed in

relation to the size of the country and its population significant increase in traffic volumes over

the past few years have not been matched by the improvement in the road system. To operate a

maintenance system and 10-20 years long term strategic road maintenance plan for few road

network on the basis of prioritization for road maintenance needs of roads. The surface condition

of National Highways has been maintained at a reasonable level but the underlying strength of

many of pavements is poor and gradually deteriorating. The surface condition of Regional

Highways has got worse and underlying pavement strength is low, the value of any

reconstruction, rehabilitation and periodic maintenance will be fruitless. To operate system

needs a wide range of data which comprises of road condition, traffic, pavement, axle load of

vehicular traffic etc.

1.2 OBJECTIVES OF THE STUDY

The main objective of the research work is to perform a detail survey and investigation of

existing road condition. Based on the result of the investigation over lay design will be

performed to strengthening the existing road.

Therefore this study is taken up with an objective to evaluate pavement characteristic by various

methods:

i) To assess the road condition to know the degree of distresses.

ii) To carry out the traffic count and traffic classification survey to know the adequacy of

pavement structure for present day traffic and loading.

iii) To assess the need for structural overlay on distressed pavements.

2

1.3 SCOPE AND APPROACH OF STUDY

This work is carried out on Dhaka-Sylhet Road (15 km to 25 km – N-2) for evaluation of

existing pavement and behavior of the existing road condition. The results of this study can be

used to take the road surface improvement programme of the existing road network. The finding

of the study shall be applied to check the performance of existing pavement and to asses the

need for structural overlay on distress pavement. The scope of the study involves the following

tasks.

1. Study the assessment of the pavement conditions.

2. Study the strength of existing pavement by measuring surface deflection by the

Benkelman Beam.

3. Study the traffic count data classified traffic count and growth rate of traffic.

To achieve the study objectives, a systematic approach consisting of three main interconnected

phases have been framed:

The first phase consists of literature review, detail survey of pavement surface and to prepare the

road inventory of full 10 km stretch. The second phase consists of collection of deflection data

by Benkelman Beam test and traffic count. The third phase involves data analysis interpretation

of results, conclusions and recommendations.

1.4 ORGANIZATION OF THESIS

Chapter 1 presents the an overview of the problems being experienced with respect to

maintenance of existing pavement, the objectives, scope and approach of the study to arrive at

conclusion.

Chapter 2 is to review the literature on the subject matter. The chapter also covers the finding of

researchers in the past to take account of those in the current study.

Chapter 3 presents the details of methodology and data collection.

Chapter 4 presents test results, their analysis and evaluation adopting statistical approach and

discussion for final conclusion for improvement of strength of existing pavement.

Chapter 5 presents the final finding and conclusion of the study. Recommendation for further

researches and studies are also included in this chapter.

3

CHAPTER 2

LITERATURE REVIEW

2.1 GENERAL

Maintenance of roads in timely manner is a cost effective process. Minor types of surface

distress require repair as soon as detected. Maintenance works like over lay rehabilitation and

partial reconstruction need huge investment. Such investment, can be avoided if the routine and

preventive types of maintenance works of road are done in time. To identify the surface

distresses in the pavement needs proper assessment of pavement condition. The following types

of surface distress cause gradual deterioration of the pavements leading to its total failure. To get

first hand information of the pavement condition, road agencies develops the method of

surveying of the pavement condition and same procedure adopted for preparation of project.

Characteristics of Different Types of Surface Distresses of Bituminous Pavement are described

below:

2.2 TYPES OF SURFACE DISTRESSES

Cracks: Cracking is one of the dominant features of the surface distress in bituminous

pavement. Inadequate pavement thickness, shrinkage of asphalting surface due to temperature

cycle, fatigue due to repeated cycles of stress, overheating of bitumen, and impact of excessive

vehicular load differential settlement of cut and fill of the road embankment, displacement of

joints between two lanes, are some of the major attributing factors for forming cracks in

bituminous surface. It should identify weather the road pavement is suffering from load or non

road associated distress.

Accumulated water of the pavement surface infiltrates into the underlying layers of the

pavement. It causes immense damage leading to gradual failure of the sub grade. The forms of

predominant types of cracks are of mainly of five types. Secondly it should establish whether the

severity of cracking will affect the performance of any subsequent new pavement lay by causing

reflection cracking (Rolt et al, 1996).

4

Figure 2.1 Picture shows cracking in asphalt surfacing at Ch. 22+000 km

Asphalt concrete roads will generally deteriorate either by rutting or by cracking. To help

identify the cause of the deterioration, rutting and cracking have been subdivided into five

categories based on the nature of the failure its position and the type of road construction.

2.2.1 Wheelpath cracking asphalt surfacing: If cracking is caused primarily by traffic it

must, by definition, originate in or near the wheelpaths. In severe cases it is sometimes difficult

to be sure whether the failures start in the wheelpath or whether they are a progression of

another form of cracking, (Dickinson, E. J., 1984). The initial type of cracking should be

identified.

Short irregular longitudinal cracks in the wheelpaths are often the first stage of traffic induced

fatigue of the surfacing which, after further trafficking, interconnects to form crocodile cracks.

Although caused by the flexure of the surfacing, they are not necessarily `traditional’ fatigue

cracks which start at the bottom of the asphalt surfacing and propagate upwards. In tropical

climates the bitumen at the top of asphalt wearing courses oxidises rapidly (Smith et al, 1990).

This causes the material to become brittle and results in cracking being initiated at the top of the

surfacing rather than at the bottom, despite the strains being lower (Rolt et al, 1986).

Where crocodile cracks are shown, by coring, to have started at the bottom of the asphalt layer,

then they are likely to be traditional fatigue cracks caused by excessive strains at the bottom of

the surfacing. Excessive strains can be caused by a weak sub-grade, giving rise to large

maximum deflections, or a weak road base leading to small radii of curvature. However, in both

cases the cracking is frequently associated with rutting; in the former case, because of

5

insufficient load spreading; in the latter case, because of shear failure in the road base. In

practice this type of crocodile cracking very rarely occurs without any rutting.

In some circumstances traditional fatigue cracking can occur simply because the road has

reached the end of its design life; in other words no other form of failure has occurred

beforehand. This is a relatively rare phenomenon and for this reason is sometimes difficult to

identify because of the need to calibrate standard asphalt fatigue relationships for local

conditions. However, the age of the surfacing and the traffic carried should provide the most

important clues.

Poor surfacing materials can also result in crocodile cracking. Inadequate quality control

exercised during the manufacture and construction of dense surfacing can lead to poor particle

size distribution, low bitumen contents, segregation and poor compaction, all of which will

make the material more susceptible to cracking. Failures of this type can occur in areas where

deflections are satisfactory and where little or no rutting is occurring.

If the bond between the asphalt surfacing and the underlying layer is poor then the surfacing can

effectively `bounce’ under traffic. This quickly results in crocodile cracking in the wheel paths

and is characterized by blocks of less than 200 mm square. The cause of the poor bond can be

ineffective priming of the road base, of deficient tack coat prior to placing an overlay. Often the

cracking will progress to laminations, which are shallow potholes that are clearly the result of

the surfacing `peeling’ off;

Parabolic shaped cracks in the surfacing which occur in areas of severe braking such as the

approaches to junctions and sharp bends are caused by slippage and are also the result of a poor

bond. Small areas of parabolic cracking are not indicative of serious failure. However, if it is

more extensive, the probable cause is an inadequate tack coat or the use of soft aggregate in the

surfacing which, in breaking down, results in a poor bond and subsequent slippage.

Cracking in bituminous overlays, particularly in the wheelpaths, can be caused by cracks in the

underlying layer `reflecting’ through the overlay. Reflection cracking will generally occur early

in the life of the overlay and is often associated with pumping of fine material from a lower

granular layer. Cores cut through cracks in the new overlay will establish whether they are being

caused by existing cracks in a lower pavement layer.

6

2.2.2 Non wheelpath cracking asphalt surfacing: The cause of non traffic associated

cracking in an asphalt surfacing is largely established by identifying its type. As traffic has

played little or no part in these road failures the cracks will not be confined to the wheelpaths

and there will not be any substantial rutting. Non wheelpath cracking can take the form of

longitudinal, transverse, block or crocodile cracking. It is recommended that five types of cracks

consider. These are as follows:

L - Longitudinal cracks

T - Transverse cracks

B - Block cracks

C - Crocodile cracks

P - Parabolic cracks

2.2.3 Longitudinal Cracking: Cracking forms almost parallels to the centerline of the

pavement and hardly shoot out branches transversely. Thermal stresses can cause cracks to

appear along poor longitudinal construction joints and in areas of severe temperature gradients,

such as the edge of road markings. In their early stages neither of these types of crack is

particularly serious; however, if left unsealed, the cracks will eventually spread into the

wheelpaths where they will result in more serious deterioration.

Where longitudinal and transverse cracks occur in combination, they are likely to be either

reflection cracks propagating from a lower stabilised layer or cracks caused by thermal or

shrinkage stresses in the asphalt. Longitudinal cracks caused by sub grade movement will

generally be quite long and can meander across the carriageway. They can occur because of poor

construction, swelling in plastic sub grade or embankment materials, and the settlement or

collapse of embankments. Cracks caused by the slippage of an embankment will often occur in

semicircular patterns and both these and cracks caused by sub grade movement will often be

associated with a vertical displacement across the crack.

2.2.4 Transverse Cracking: Cracking form transversely across the pavement. Transverse

cracks in the surfacing of a road pavement which includes either a chemically stabilised road

base or sub-base are likely to be reflection cracks from the stabilised layer, particularly if the

stabiliser is cement. This form of transverse cracking is often associated with longitudinal cracks

and in severe cases, blocks cracking.

7

If the transverse cracks are irregularly or widely spaced they are likely to have been caused by

some form of construction fault. Differential vertical movement caused by consolidation or

secondary compaction adjacent to road structures and culverts can cause transverse cracks in the

surfacing. These cracks will be associated with a poor longitudinal road profile caused by the

differential movement.

Transverse cracks confined to the surfacing and occurring at more regular and shorter spacing

are probably caused by thermal or shrinkage stresses. This type of cracking will most likely

occur in areas subject to high diurnal temperature changes, such as desert regions, and will be

exacerbated by poor quality surfacing materials. When cracks occur after many years good

performance it is likely that progressive hardening of the binder has made the surfacing more

brittle and therefore more susceptible to cracking. As transverse thermal cracks progress, they

will link up with longitudinal ones to form block cracking. Thermal stress can also causes cracks

to open up at transverse construction joints.

2.2.5 Block Cracking: Block cracking when confined to the bituminous surfacing is usually

the final stage of cracking due to thermal stresses. These cracks almost always start at the top of

the surfacing and propagate downwards. Block cracking can also occur though reflection of the

shrinkage crack pattern in lower chemically stabilized layers.

2.2.6 Crocodile Cracking: Cracking consists of interconnecting or interlaced cracks forming

a series of small polygons like crocodile skin. Crocodile cracking that is neither confined to the

wheelpaths nor associated with rutting is indicative of a fault in the construction of the

surfacing. The more common production faults are poor particle size distribution, low binder

contents, overheated bitumen and the use of absorptive aggregate. Construction faults include

poor compaction, segregation of the mix and poor bonding; wither between layers of bituminous

material or the granular layer beneath. In these cases the precise cause of failure can only be

determined by destructive sampling and laboratory testing.

2.2.7 Parabolic Cracks: Parabolic shaped cracks in the surfacing which occur in areas of

severe braking such as the approaches to junctions and sharp bends are caused by slippage and

are also the result of a poor bond. Small area of parabolic cracking is not indicative of serious

failure. However, if it is more extensive, the parabolic cause is an inadequate take coat or the use

of soft aggregate in the surfacing which, in breaking down, results in poor bond and subsequent

slippage.

8

Intensity: It is in pertant to identify the position of the cracking. The cracking can be confined to

either or both of the verge side (V) and off side (O) wheel path, or can be spread over the entire

carriageway.

Width: Four types are recommended as listed below (Patterson, W.D.D., 1987). The first three

are for cracks which are not spalled, cracks with substantial spalling are classified as width 4.

The widths of the cracks usually vary within any block and so it is the width of cracks that

predominates that is recorded.

1) Crack width < 1 mm

2) 1 mm <crack width < 3 mm

3) Crack width > 3 mm

4) Crack width spalling

2.2.8 Potholes: Potholes are bowl-shaped holes formed in the pavement surface. These are

formed due to loss of wearing course and base course material, absorption moisture in to base

course through cracks of pavement surface. The potholes are developed when plying vehicles

abrades small pieces of the pavement surface (cracking delaminating, etc) allowing the entry of

water.

Figure 2.2 View of pothole at Ch. 16+050 km

The potholes have sharp edges having its sides nearly vertical at the top of the hole. The

materials in the potholes disintegrate very rapidly while water is accumulated in pothole. The

moving vehicles further deteriorate the situation by increasing not only the size of the potholes

but also increase the number within the vicinity of the effected area. The unit of measurement is

9

square meter. It was noted during the survey work that no major potholes in the 10 km stretch. It

was also observed that due to number of cracks, the potholes may increase in future.

2.2.9 Delamination: Delamination is developed on the top surface of pavement due to loss of

a discrete and large (0.01 m2) area of the wearing course. The causes are inadequate cleaning or

inadequate tack coat before place of upper layers of bituminous layers, seepage of water through

asphalt to break bond between surface and lower layers, weak layers immediately underlying

layers, adhesion of surface binder to vehicle tyre, etc. The unit of measurement is square meter.

2.2.10 Depression: Depression is a common type of surface distress of the pavement that

makes elevation of a certain area within pavement lower than surrounding area. Such area may

not be confined only along wheel paths and could extend across several wheel paths. Causes are

consolidation of isolated areas of soft or poorly compacted sub grade or embankment materials,

settlement of pavement layers due to instability of embankment, settlement of service and

widening trenches, etc.

2.2.11 Pavement Rutting: Rutting is defined as a longitudinal depression that forms along the

wheel path under impact of vehicular traffic. The length of depression should at least 6 m that

distinguish it from pavement failures of localized nature. Ruts are channelized depressions

which may develop in the wheel tracks of an asphalt pavement. Rutting can be due to the

channelization of traffic. As the traffic has to pass in the same channel repeatedly, therefore

channelization depressions are developed Because of the high asphalt contents and increase in

flow value of hot mixes ruts are developed.

Channels may result from consolidation or lateral movement under traffic in one or more of the

underlying courses or by displacement in the asphalt surface layer itself. They may develop

under traffic in new asphalt pavements that had too little compaction during construction. They

may develop due to the plastic movement in a mix that does not have enough stability to support

the traffic.

To avoid ruts it is better to keep the job mix formula to wards the coarser side and in this way

low asphalt content will be achieved in the design and consequently sufficient voids will be

obtained to allow for a slight for a slight amount of additional compaction under traffic without

flushing. Roads may be designed keeping in view the total volume of traffic over them.

10

2.2.12 Raveling: Raveling results from progressive disintegration of the pavement surface by

loss of both binder and aggregates. Causes are deterioration of binder and stone, inferior asphalt

mix design, inadequate compaction, and construction during wet or cold weather. The unit of

measurement is square meter.

2.2.13 Broken Edge: Edge breaking of the pavement surface results from inadequate pavement

width defective alignment encouraging drivers to drive on pavement edges, inadequate drop-off,

weak seal coat, and loss of adhesion to base. The effective width of the pavement reduces due to

breaking of edge of the pavement. Usually, edge cracks are due to lack of lateral (shoulder)

support. They may also be caused by settlement or yielding of the material underlying the

cracked area, which in turn may be the result of poor drainage, frost heave, or shrinkage from

drying out of the surrounding earth. In the last case trees, bushes or other heavy vegetation close

to the pavement edge may be a cause.

Figure 2.3 Picture shows view of broken edge at Ch.15+100 km

Edge failure caused due to poor shoulder maintenance and due to this leaves the surface of road

pavement higher than the adjustment shoulder. This unsupported edge is broken away by traffic

throughout the stretch and some places the edge of NMT lane severely damaged which is

provided along the road on both side and the extent of the defect measured as follows:

Extent Length of block affected (percent)

1 <10

2 10-50

3 >50

11

2.3 FAILURE IN ASPHALT PAVEMENTS AND CONTROL OF SUCH

FAILURE

Failures in asphalt pavements are an acute problem of the present day. In all cases of pavement

distress it is the best to determine first the causes of difficulty.

Table 2.1 Failure in asphalt pavement and control of such failure

Failures Controls

1. At the present time many asphalt pavements

consist of an asphalt surface over a granular

base. These bases serve well as long as they

are properly drained. But if they become

saturated with water they loose strength

rapidly under the weight and action of traffic.

Saturation of granular bases is the cause of

many failures in the pavement and hence many

maintenance problems arise. Among them are

asphalt surfaced pavements on granular bases

that become soft and crack in the familiar

alligator or chicken wire pattern.

1. Some high type pavements with granular

bases are designed with drainage system to

prevent saturation by ground or surface water.

2. There are many thousands of miles of sand

clay gravel roads surface with asphalt that

become saturated and give trouble. Usually

these roads have a high percentage of plastic

fine materials in them as binder. As sand clay

gravel roads become saturated when it rains

with the result water is migrating into the base

materials from the shoulders and from the sub

grade below cannot escape and the sand clay

gravel loses strength as it becomes soaked.

Cracking, heaving and others forms of distress

take place in this way. Also, in its weakened

conditions the base unable to support the

traffic deflects more than normal and cracking

is intensified.

2. Therefore, when investigating surface

failures which appear to be related to excessive

deflection, the base should be checked for

plastic fines or trapped water. If so, repair may

call for digging out the broken area to sound

material improving drainage and patching with

asphalt patching mixture.

(Contd...)

12

Table 2.1 Failure in asphalt pavement and control of such failure

Failures Controls

3. Due to lack of lateral or shoulder support for

the asphalt pavement, edge cracks appear on

the surface. Such cracks are also caused by

settlement or yielding of the material

underlying the cracked area which in turn may

be the result of poor drainage, frost, heave or

shrinkage due to drying out of the surrounding

earth. In the last case trees, bushes or other

heavy vegetation close to the pavement edge

may be a cause of failure.

A common cause of “cracking in a pavement

shoulder joint is alternative wetting and drying

beneath the shoulder surface. This may result

from poor drainage due to a shoulder higher

than the main pavement. Lane joint cracking is

caused by a weak seam between adjoining

spreads in the courses of the pavement.

3. Drainage problems are either (a) surface or

(b) sub surface, each require separate analysis

and treatment. A pavement surface should be

free from holes and cracks, have a permanent

tight joint with the shoulder and be shaped and

sloped for adjacent run off. The most effective

shoulder drain is one that has been

waterproofed with an asphalt surface. A less

effective practice (but still acceptable) is to

cover road shoulders with an aggregates

graded to minimize seepage into the sub-grade.

4. Shrinkage cracks are caused by volume

change of fine aggregate asphalt mixes that

have a high content of low penetration asphalt.

Pavement distortion is the result of sub-grade

weakness. Pavement distortion is any change

of the pavement surface from its original

shape. It usually is caused by such things as

too little compaction of the pavement, too

much asphalt, swelling of underlying courses,

or settlement. Like cracks, distortion takes a

number of different forms, grooves or ruts,

shoving corrugations, depressions and

upheavals.

Ruts are channalized depressions that

4. The preparation of an accurate and precise

hot mix design is very essential to overcome

most of the failures on asphalt pavement. The

correct value of optimum asphalt content in

asphalt mix design enable us to avoid bleeding,

rutting, corrugations and shoving and pot

holes.

Mix with abnormally higher values of

Marshall Stability and low flow values are

often less desirable because pavements of such

mixes tend to be more rigid or brittle and may

crack under heavy volume of traffic. If the

stability is abnormally higher, it can be

controlled by reducing the coarse aggregates

(Contd...)

13

Table 2.1 Failure in asphalt pavement and control of such failure

Failures Controls

depressions that develop in the wheel tracks of

asphalt pavements. Rutting may develop under

traffic in new asphalt pavements that had too

little compaction during construction or from a

plastic movement in a mix that does not have

enough stability to support traffic.

Corrugations and shoring also usually occur in

asphalt pavement that lack stability. This may

be the result of too much asphalt, too much the

fine aggregates or round or smooth textured

coarse aggregates. In the case of emulsified

and cut back asphalt mixes, it may be due to a

lack of aeration. Upheaval may be caused by

the swelling effect of moisture on soils.

Disintegration is the breaking up of a

pavement in to small, loose fragments. This

includes the dislodging of aggregate particles.

Pot holes and raveling frequently appear in the

pavement. Potholes are usually caused by

weakness in the pavement resulting from too

little asphalt too thin an asphalt surface, too

many fines, too few fines or poor drainage.

Raveling is caused by poor construction

methods, inferior aggregates or poor mix

design.

Slippery surfaces on asphalt pavements are

caused by bleeding of asphalt pavement.

Pavement courses having rich asphalt mixes,

improperly constructed seal coats or too heavy

a prime or tack coat may form bleeding and

flushing.

and adding fine aggregates more. We should

adjust our asphalt mix design in such a way

that the job mix may fulfill the traffic

conditions. Coarser job mix for heavy traffic is

the most suitable only for medium to light

traffic. Therefore in evaluating and adjusting

the mix design note that the aggregate

gradations and asphalt content must strike a

favourable balance between the stability and

durability requirements for the use intended.

Stability can also be reduced by reducing

asphalt contents but the care should be adopted

not to use little asphalt contents to avoid

further problems in the pavement.

Stability can also be reduced in case the

percentage of crushed sand may be lowered

but care should be taken that excess quantity of

natural sand may not be used.

High stabilities are also obtained if the

compacting temperature of asphalt is very high

even more than 1500C. The compaction

temperature of asphalt during the Marshal test

should be 145 ± 50C.

(Contd...)

14

Table 2.1 Failure in asphalt pavement and control of such failure

Failures Controls

5. Too much asphalt brings the problem of

corrugation and shoving in the pavement.

Bleeding on the road is also due to the high

asphalt content in the hot mix. Too little

asphalt content brings the problem of pot holes

in the pavement.

5. An accurate job mix formula in hot mix

design will enable you to avoid many failures

in the pavement. Quality of aggregates in hot

mix design also plays an important role to

avoid many failures.

6. Inferior type of aggregates in the pavement

causes ravelling. Naturally smooth uncrushed

gravels are polished under the abrasive action

of traffic.

6. The aggregates must be hard and angular.

The shape of aggregate is determined by the

percentage of flaky and elongated particles

contained in it. In case of gravel it is

determined by its angularity number. The

presence of flaky and elongated particles is

considered undesirable as they may cause

weakness with possibilities of breaking down

under heavy load. Angular shape of particles

are suitable for granular base course and

bituminous wearing course and bituminous

base course due to increased stability derived

from better interlocking.

7. Sufficient air voids in hot mix are needed to

be maintained. As they allow for a slight

amount of additional compaction under traffic

without flushing bleeding or rutting. The air

voids should not be abnormally higher as to

avoid permeability and premature hardening of

asphalt pavement. Low air voids in hot mix

will also cause rutting

7. Plasticity index of fine aggregates should

not be more than three (3) as more plasticity in

hot mix reflects the swelling properties of clay.

Air void normally in wearing course ranging

from 3% to 5%. It should be maintained during

the job mix formula.

8. Penetration of asphalt used in hot mix plays

an important role to avoid failures. High

content of low penetration asphalt creates the

volume change in asphalt mix causing

shrinkage cracks in the pavement.

8. So in the hot areas it is better to use low

penetration asphalt. In case of high grade

asphalt bleeding problems will start in the

pavement.

(Contd...)

15

Table 2.1 Failure in asphalt pavement and control of such failure

Failures Controls

9. The strength of Embankment is reduced

because of low filling and a weak foundation

and the pavement is cracked due to heavy

traffic.

In some cases the Embankment layers below

asphalt pavement are not compacted as

required and because of heavy traffic, cracks

start appearing in the pavement due to the

settlement of materials.

9. Embankment should be compacted in layers

as per the specification. For given moisture

content, compacting efforts are applied on

resulting in closer packing of soil particles and

increase in dry density. Moisture content at

which the soil is giving maximum dry density

should be determined before start the filling at

site.

10. Some mix deficiencies in hot mix design

create many problems in the pavement.

Overheated asphalt affect many properties of

hot mix. It gives you less stability and more

loss. On the other hand hot mix which

indicates low temperature far from the

specified limit shows improper coating of the

large aggregate particles. A mix with excess

coarse aggregate can be detected by the poor

workability and by its coarse appearance when

it is on the road. Such pavements with excess

coarse aggregates or excess fine aggregates

will not be durable and compacted as required

and air voids will vary from place to place. In

case the compaction requirements of the

pavement are not fulfilled, the pavements have

to meet with many failures. Durability and

water tightness are the factors which are

mainly concerned to make long life

pavements. Most of the problems on the roads

are observed due to the poor pavement

designs.

10. An accurate job mix formula in hot mix

design will enable you to avoid many failures

in the pavement. Quality of aggregates in hot

mix design also plays an important role to

avoid many failures.

In pavement construction flaky and elongated

particles are to be avoided, if they are present,

the strength of pavement layer would be

adversely affected due to possibilities of

breaking down under heavy load.

It is possible to improve the stability and

increase the voids of the mix by increasing the

amount of crushed material. Care should also

be adopted in the use of asphalt content. In

case of low voids asphalt contents can be

lowered but not beyond certain limit as to

affect other properties. Hot mix having little

asphalt cannot be compacted properly.

(Contd...)

16

Table 2.1 Failure in asphalt pavement and control of such failure

Failures Controls

11. Flexible pavement consists of multilayered

entity where each layer is stronger than the

underlying layer. Top layers are subjected to

greater stress and strain than the bottom layers.

In most of the cases the asphalt is laid down on

the sub-grade layer with inferior materials.

Such materials become saturated with water if

it rains or due to accidental water and loose

strength under the weight and action of traffic.

In Bangladesh the requirement of sub-grade

materials is very poor and the chances of

failures are more as compared to the other

countries.

11. In such circumstances it is better to use

sub-base and aggregate base course after sub-

grade layer. In the presence of sub-base and

aggregate base course layers, even the

thickness of pavement can be reduced keeping

in view the economy factor, if necessary. As

we move from sub-grade to asphalt, materials

from good to the excellent quality may be

used.

Sub-base and aggregate base course should

consist of well graded sound and hard material

which will provide protection to sub-grade

from frost and heave and at the same time it

will reduce the traffic presence on the sub-

grade which is likely to be over moisturized

due to various reasons.

12. The worst aspect of frost action is the

weakening of sub-grade during thawing. Soil

and moisture conditions which are critical for

heaving also are critical for thawing damage.

Another very bad effect of the spring thaw

many occur in granular bases over fine grained

sub-grades. Fines are carried into the granular

base, transforming it from a satisfactory base

material into a material of low load carrying

capacity.

12. The effects of spring thaw can be

minimized by using proper drainage. An

asphalt pavement structure consists of courses

of asphalt aggregate mixtures plus any non-

rigid courses between the asphalt construction

and the sub-grade. The sub-grade ultimately

carries all traffic loads. Therefore, the

structural function of a pavement is to support

a wheel load on the pavement surface and

spread and transfer that load to the sub-grade.

13. In some cases the over compaction of sub-

grade sub-base and base course layers also

participate in cracking of the pavement to

some an extent. Over compaction produce

cracks in these layers and pavements are also

affected by such effects.

13. Over compaction should be avoided which

causes the cracks under the load.

(Contd...)

17

Table 2.1 Failure in asphalt pavement and control of such failure

Failures Controls

14. Full depth asphalt pavements have many

advantages, and one of the most important is

their ability to resist pavement stresses.

Resistance to the destructive effects of ground

water moisture is also a quality of such

pavements but their failures in most of the

cases has become an acute problem. Such

pavements if constructed directly on weak sub-

grade having very poor material and poor

drainage cause the sub-grade to loose stability

and support and failure occurs.

14. In developing the various features of

drainage system, consideration should be given

to its principal purposes which are:

i) To collect and drain surface and sub

surface water

ii) To prevent or retained embankment

erosion

iii) To intercept water from surrounding

areas and carry it from the area: and

iv) To lower the ground table

15. Water logging and salinity in the areas

where road is being constructed also create

many problems. Continuous rise of salts give a

very destructive effect to the road.

15. In this case a sub base with sandy gravely

materials (A-1-b) will act as a cut off layer

against possible rise of salts from the sub grade

and to prevent resulting salt boils. It will also

act as a moisture rise barriers against normal

upward travel of moisture through capillary

action.

As already pointed out, pavements, must be designed to serve traffic needs adequately over a

period of years. Traffic growth must therefore be anticipated when determining structural

requirements of the pavement. The cumulative effects of traffic loads are very important factors

in the structural design of a pavement. Both the initial traffic conditions and the manner in which

they may be expected to change must be evaluated. An adequate and economical design for a

pavement structure is just as important as a design for any other engineering structure. An under

designed pavement will fail just as surely, although perhaps not as spectacularly, as other types

of structure. A wasteful over design, or a selection of materials that are not the most economical

and suitable for the design, is contrary to the standards of sound engineering. Vehicle weights,

traffic volume, and tire pressures are steadily increasing and demanding more and more from the

pavement structures. Engineers face with serious problems with the quality of paving material.

Often aggregates are transported from long distances at high cost because local aggregate

supplies of high quality have been depleted. As a result, additives to AC mixes have been widely

accepted by the paving industry for the present time (Joe, W.B.,1991).

18

The desired practical and functional quality attributes in a filler material should include the

following (Warden et. at., 1959):

The filler in the bituminous mix must be non critical. Variations in the filler content which may

be expected under normal plant operation must not cause undesirable fluctuations in the physical

properties of the pavement. The quantity of filler desired for functional reasons must not

unfavorably affect the mixing, placing and compaction of the bituminous mixture. In other

words at the desired concentration to meet design criteria the mortar softening point or

consistency must not be so high that the mix is unworkable.

Added mineral filler should be economical (Availability and cost) and should be readily

transported, stored, proportioned and mixed with customary equipment. Yardsticks for storing

and proportioning are that the filler be non-hygroscopic and do not form lumps or cake or bridge

in the bins. A completed pavement surfacing must be stable and durable over a wide range of

temperature and over an extended period of time. This means that from the functional viewpoint

the type and quantity of filler in the bituminous mixture must be such that the optimum void is

maintained within the desired limits, both initially and after ultimate compaction, and that there

is sufficient resistance to deformation by traffic at the highest service temperature. Concurrently

the filler must not decrease the resistance to water or the bond of the bitumen or mortar to the

aggregate and must not decrease durability through loss of flexibility by inducing cracking of

the pavement.

In general the functions of filler can be listed as follows (Khanna., P. N., 1992):

1. To increase the viscosity of the binder and hence increase density and stability of the

mixture.

2. To enable a thicker film of binder to be held by the mixes.

3. To improve the resistance of the binder to weathering.

4. To increase the effective volume of the binder

5. To reduce the apparent temperature and water susceptibility of the mixture (for dense

surfacing-filler/binder mixtures have lower temperature and water susceptibility than

straight binders of the same viscosity).

6. To reduce the brittleness of a mix in cold weather, where the quantity of the filler can be

considerably increased.

19

2.4 BENKELMAN BEAM DEFLECTION

The simplest method of measuring the deflection of a road pavement is to use a loaded lorry and

this deflection beam originally devised by AC Benkelman. The elastic deflection of pavement

which has been subjected to traffic depends upon various factors such as:

1. Sub-grade soil type

2. Moisture content and compaction of sub-grade soil

3. Pavement thickness, composition quality and condition

4. Drainage conditions

5. Pavement surface temperature

6. Wheel load

The Benkelman beam is a handy instrument which is most widely used for measuring deflection

of pavements. It consists of a lever 3.66 m long pivoted 2.44 m form the end carrying the contact

point which rests on the surface of the pavement. The deflection of the pavement surface

produced by the test load is transmitted to the other end of the beam where it is measured by a

dial gauge or recorder. The movement at the dial gauge end of the beam is one half of that at the

contact point end.

2.5 SUMMARY DISCUSSION

Details in this chapter have been devoted to illustrating several types of distress manifestations

commonly found on highway pavements. The list of types of distress is by no means complete,

but is intended to acquaint with some of the most common types. It is required to evaluate

whether the distress represents a functional or structural failure of the system.

20

CHAPTER 3

RESEARCH METHODOLOGY AND DATA COLLECTION

3.1 GENERAL

Detail survey and investigation of existing road condition were carried out to know the structural

performance of highway. Details are discussed in this chapter.

3.2 STUDY AREA

The work is carried out on Dhaka-Sylhet Road (15 km to 25 km N-2). Location map is shown in

Figure-3.1

3.3 METHODOLOGY OF BENKELMAN BEAM TEST

The transient deflection test was carried out in order to examine the performance of a flexible

pavement. It has been established that the performance of a flexible pavement is related to its

deflection. The transient deflection tests are based on the concept that the pavement structure

deforms elastically under the design test load. The Benkelman beam designed by A. C.

Benkelman is being used extensively for measuring the deflection of flexible pavements under

the action of moving loads. Highway sections having high deflection value are likely to give

poor performance and have shorter life. The sections which show low deflection may need little

maintenance and posses long life. The Benkelman beam is a handy instrument which is most

widely used for measuring deflection of pavements. The test carried out is described below:

Operating Team: For deflection beam operations the team consisted of nine men:

a) Beam operator 2

b) Recorder 2

c) Labours 2

d) Flagmen with flag 2

e) Lorry driver 1

Measuring Equipment: The essential equipment required to carry out a deflection survey is

given in below:

Two deflection beams and a suitable lorry with approximately new tyre

A mercury in glass stirring type thermometer

A road marking crayon (chalk)

A straight edge 2 m in length and calibration wedge

Suitable road signs, flags.

Hand level (Spirit level)

21

Figure 3.1 Location Map

22

Test Location: Deflection measurement was made in wheel path of one lane of a road at a

spacing of 200 to 500 m with additional tests at locations where there was a visible deterioration

in the condition of the surface.

The length of road on which measurements are to be made were carried out after suitable

warning signs have been erected on the verge ahead of the area. The advice and help of the

traffic police was taken during the test.

3.3.1 Benkelman Beam Testing

Research carried over a number of years has established that a significant relation exists between

the magnitude of the deflection of a road pavement under a wheel load and the structural

performance of that road under traffic.

The relationship established between the deflection of road pavements and there long term

performance under traffic provide the engineer with a relatively simple means of forecasting the

future performance of existing roads and designing measures for their structural strengthening.

Basic Principle: A well compacted pavement section or one which has been well conditioned

by traffic deforms elastically under each wheel load application such that when the load moves

away, there is an elastic recovery or rebound deflection of the deformed pavement surface. this

elastic deflection under a given wheel load is dependent on the sub grade soil properties, its

compaction and moisture content, the thickness and quality of the materials in various pavement

layers, pavement drainage conditions, and its surface temperature etc. The amount of this

deflection is an indication of the strength of the existing pavement. This is the basic principle of

deflection method of pavement strength evaluation. Depending on the expected projected ESA

over the design life deflection values ranging from 0.80 to 1.50 mm under the specific standard

wheel load are generally considered to indicate satisfactory strength. Higher values would mean

requirement of an overlay, which can be estimated by standard formula or charts.

Details of the Benkelman Beam: The Deflection Beam was developed by AC Benkelman in

the United States and is often referred to as the Benkelman Beam. Deflection of the road surface

as a wheel passes over it is measured by the rotation of a long pivoted beam in contact with the

road at the point where deflection is to be observed. A long beam was essential to ensure that the

pivot supports are remote from the influence of the loaded wheel at the time of measurement.

23

The aluminum alloy beam 3.66 m in length and is pivoted at a point 2.44 m from the tip giving a

2:1 length ratio on the other side of the pivot. The pivot is carried on a frame supported by three

adjustable legs. The frame also carries a dial gauge arranged to measure the movement of the

free end of the beam. The dial gauge has a 75 mm diameter face, a travel of 25 mm and 0.01 mm

graduations.

For traveling purposes, the beam is locked by the rotating handle grip. To minimize sticking at

the pivot during recording, vibration of the beam is desirable; this is provided by an electric

buzzer (with battery and hand switch) mounted on the frame. I case the buzzer may be out of

order, mild continuous tapping of the frame by the finger is suggested at the time of taking the

observation. It is important to ensure that the adjustable legs are used to vary the height or the

beam. This is achieved by screwing the shaft of legs while maintaining the feet captive. The

beam is spited into two parts for ease of transportation and is therefore essential that the

connecting plate is tightly secured before use.

The Benkelman Beam calibrated before starting the deflection measurements to ensure that the

dial gauge and beam are working properly. For this purpose the beam is placed and leveled on a

hard level ground. A number of metallic plates of varying thickness (measured accurately with a

precision micrometer) with perfectly pane faces are placed under the probe and the dial gauge

reading recorded each time. If the beam is in order, the dial gauge on the beam should give the

correct thickness of the plate on which the probe was placed by multiplying the figure shown by

the dial gauge with the applicable factor for the beam. (If any error is detected then the dial

gauge is checked and replaced if necessary). If the dial gauge is functioning correctly, the beam

pivot needs to be checked for free and smooth operation. Also the striking plate beneath the dial

gauge spindle need to be checked to ensure that it is tightly secured and has not become grooved

by the dial gauge stylus.

It is necessary to handle the dial gauge with care, the stem of the gauge polished with a dry, soft

cloth and checked for free movement before testing was started. The stem is also polished

periodically during each time of testing to remove any deposits.

Loaded Lorry: The Two axle lorry was used for deflection measurements. It should have an

accurately measured rear axle load; the load to be equally divided between the twin wheel

assemblies.

24

An open bodied vehicle, loaded with bricks is satisfactory. It is essential that the load should not

shift during testing and for this reason loading with sand or gravel is unacceptable and it should

not absorb or trap water which would cause the magnitude of the axle load to change.

Figure-3.2 Picture shows vehicle loaded with bricks

It may be noted that there exist different practice of adopting the rear axle load for undertaking

the tests. The common practice is to use the standard axle load of 8160 kg. Care must be taken

however not to confuse the deflection criteria applicable to one axle load with those applicable

to the other. The advantages of using the less axle load (6350 kg) are that a smaller lorry can be

used and running costs will generally be lower. If the test is undertaken with an axle load

different from the standard axle load a pro-rata correction to the deflection reading may become

essential.

Figure 3.3 Picture shows measuring the air pressure of tyre

25

Table 3.1 Details of vehicles suitable for test

Deflection Testing Characteristic

Rear axle load 8160 kg

Dual rear wheel load 4080 kg

Front axle load 1800 kg per (wheel)

Wheel base 3.85 m

Tyre size 8.25 x 20

Tyre pressure 590 kN/m2 (85 Psi)

Gap between walls of dual 25-40 mm

Gap between contract area at dual rear at dual rear

wheels

100-150 mm

Figure 3.4 Picture shows preparation of Benkelman beam test is in progress

Deformation: Deformation or rut depth in the wheel paths can be measured by placing a 2 m

straight edge transversely to the road over the test point, any deformation below the straight

edge being measured with the calibrated wedge. No sign of deformation found in the wheel

paths during test.

Cracking: An assessment of the amount of cracking at a deflection test point can be made by

measuring the linear cracking within a one meter square frame. No sign of cracking found on

surface during the deflection test.

A convenient means of classifying the Degree of cracking (visible cracks) at a test point is given

below:

26

Table 3.2 Classify the degree of cracking at test point

Classification Index Crack length/Unit area

C1 Null

C2 Not greater than 1m/m2

C3 Greater than 1 m/m2 but not greater than 2m/m2

C4 Greater than 2m/m2 but not greater than 5m/m2

C5 Greater than 5m/m2 (raveling & potholing imminent)

The Transient Deflection Test: Smith, H.R., and Jones, C.R., (1980) explained the test

procedure used by TRL is described below: This type of test has been adopted for measuring

deflections in the UK and is the method used by the overseas unit of TRRL in the developing

countries and the same was also adopted in the study. The test is carried out in the following

steps. Details of Benkelman Beam are shown in Figure 3.5

i) Test points were marked on the near side and off side, wheel paths of the near side lane of

the road using road marking crayon; in a lane of normal width these were approximately 0.9

m and 2.7 m from the verge. The distance between test points depends mainly on the

purpose of the survey and the visual condition of the road surface.

ii) The lorry was positioned parallel to the road edge with its rear axle 1.3 m behind the test

point such that when it moved forward the test points bisected the distance between the tyre

of the dual wheels. By looking through the gap between the dual rear wheels the operator

can ensure that the beam is lying in the gap, parallel with the direction of the lorry’s forward

movement and that the tip is approximately in line with the center of the front tyre when the

front wheels of the lorry are moving straight ahead and care taken during the test. The

adjustable pointer was then aligned to the position of the beam. This position of the pointer

was then used by the operating team to place the beam in subsequent testing without

reference to the front tyre.

27

Figure 3.5 Benkelman Beam

28

iii) With the lorry in the initial stationary position a deflection beam was positioned centrally

between the dual rear wheels with its probe point resting on the test point. By using the

adjustable legs and the spirit level the frame of the beam was leveled transversely and having

checked the alignment of the beam and adjusted the licking device on the beam is released.

Adjustment of the rear foot ensured that there is adequate travel of the dial gauge spindle to

record the deflection.

iv) The vibrator was switched on and the dial gauge scale was rotated until a reading of zero was

indicated. The beam operator gave the signal the driver of lorry was driven forward at

creep speed and dial readings are taken when truck stops at 0.9 m, 1.2 m and 6 m from

the measuring point (approx 2 km/h). Vibration of the beam was continued until the lorry

has reached its stopping position. Care was taken so that rear wheel of the lorry does not

touch the beam. Details of data are shown in Appendix-A.

Sometimes during the period between setting the dial gauge to zero and the lorry actually

starting to move, the dial gauge reading may change slightly. It is recommended that this new

reading be recorded as the initial reading rather than resetting the dial gauge to zero. Records

were kept of the initial, intermediate and final dial gauge readings in a standard proforma. Initial

gauge reading was recorded when the lorry was in stationary correct position. Intermediate

gauge reading was recorded when the centre of the rear wheel reaches probe point (test point).

Final reading was recorded when the center of the rear wheel reaches 6 meter beyond the test

point. The value of deflection was calculated by adding the difference between the maximum

and initial readings to the difference between the maximum and final readings. Where the

lengths of the arms of the pivoted beam were in the ratio of 2:1 the differences between the dial

gauge readings must be doubled to obtain the actual deflection and recovery of the road surface.

The transient deflection was the mean of the loading and recovery deflections in the transient

test. Deflection = [2 x intermediate – (initial + final)]. 102 mm. Two measurements are normally

made at each test point and the mean result obtained. For deflections greater than 25 x 102 mm

the readings should not differ by more than 5% of the mean value, for smaller deflections the

difference should not exceed 10%. If the readings differ by more than the limits then additional

tests should be carried out until acceptable repeatability is obtained. The result of these

deflection tests are shown in Appendix-A.

29

Correction for Temperature Variations: For tropical and sub tropical condition the TRRL has

adopted a standard reference temperature of 35oC measured at a depth of 40 mm to which

deflection measured on temperature susceptible materials are corrected.

Correction for temperature is not necessary for roads with thin bituminous surfacing such as

premix carpet or surface dressing over a non-bituminous surfacing since these are not usually

affected by changes in temperature. But temperature correction will be required for pavements

having substantial thickness of bituminous construction (i.e. minimum 40 mm). Correction need

not be applied even in the case of thick bituminous construction if the road surface has severe

cracking or the bituminous layer is extensively stripped. The temperature was checked and

recorded. Studies have shown that the deflection pavement temperature relationship is linear

above a temperature of 30oC.

On deflection values measured at pavement temperature greater than 30oC correction for

temperature variation should be 0.0065 mm for each degree centigrade change from the standard

temperature of 35oC. The correction will be positive for pavement temperature lower than 35oC

and negative for temperatures higher than 35oC. For instance, if the deflection is measured at a

pavement temperature of 38o the correction factor will be 0.0195 mm (=3 x 0.0065), which

should be subtracted from the measured deflection to obtain the corrected value corresponding

to standard pavement temperature of 35oC. The temperature was checked and correction factor

applied shown in Appendix-A.

Correction for Seasonal Variation: As the pavement deflection is also affected by the seasonal

variations in the year arising out of the moisture content in the sub-grade soil, it is desirable to

take deflection measurements during the season when the pavement is in its weakest condition

with the maximum moisture content. Since this period occurs soon after monsoon deflection

measurements should be done during this period, as far as possible. If deflections are measured

during the dry months, they will require a correction factor. This factor is the ratio of the

maximum deflection immediately after monsoon to that of the deflection in the dry months.

Studies elsewhere have shown that for clayey sub grade soils the correction factor may be 2

whereas for sandy sub grade it may range from 1.2 to 1.3. For intermediate soil types the value

can be interpolator. The test carried out approximately in Rainy season so that correction factor

was not applied.

30

Possible Pitfalls to be Safe Guarded:

1) Truck selection: condition & gap between the twin wheels; tyre pressure, axle

load & wheel load was checked. Condition of tyre was good.

2) Ballast: brick were used as ballast. No granular material as ballast was used

because these are susceptible to shifting position influencing the wheel load.

3) While measuring the wheel load by portable weigh bridge care was taken that all

the wheels were on a reasonably level plane.

4) Accuracy of the Dial Gauge was checked

5) Leverage factor for the specific Benkelman beam for determining the multiplying

factor to the dial gauge reading should was be checked.

Temperature Measurement: The measurement of temperature was made at a depth of 40 mm

below the road surface; normally with a short stem stirring thermometer. The hole was made by

with the help of chisel and hammer. The hole was filled with glycerol before the thermometer is

inserted. Care was taken to allow any heat generated in making the hole to dissipate before a

measurement was taken. A true temperature was obtained when the same values has been read

on three consecutive observations at intervals not less than one minute.

3.4 METHODOLOGY FOR TRAFFIC STUDIES

Consecutive 2 (two) days survey for 48 (forty eight hours) was undertaken to establish AADT.

In conducting surveys the following activities were undertaken.

The station for traffic counting was selected where normal traffic flow link by

link of the road network for both direction of the road.

The survey was conducted at where traffic flow was unaffected by abnormal

conditions such as accidents.

The road width is 7.3 wide with 1.5 m wide DBST shoulder on both sides. Traffic counts were

carried out on both the lane of road. Details of cross section are shown in Figure 3.6

31

Figure 3.6 Typical cross section

32

Figure-3.7 Picture shows video traffic survey is in progress

3.4.1 Survey Technique

Considering the heterogeneous traffic mix, simultaneous vehicle occupancy data requirement

and cheaper enumerator availability a manual counting method is suggested. In comparison with

video or other automation based method, the suggested method will require low set up costs and

the ability of trained enumerators to distinguish between vehicles according to widely varying

range of parameters, type occupancy and maneuver is a clear advantage. Video recording is a

widely used and cost effective means of traffic data capture which can provide a comprehensive

and permanent record of traffic movements. One can obtain many sets of required information

regarding the mixed traffic operation from the same recorded film. Also record video tapes can

readily be used to observe the same traffic scenario repeatedly as many times as required during

analysis for this study and also for similar other studies in near future.

All the recorded flow data separately for each direction stored in DVDs/CDs. Using the

DVD/CD players captured video played back for transcribing flow data manually. In this

manual classified count method, the enumerator recorded the number of vehicles passing the

survey site along with category and selected distinctive features like length, type etc. Specially

designed forms were used to facilitate recordings of types of vehicles. Following vehicles

classification scheme was adopted during the survey:

a) Heavy Trucks

b) Medium Trucks

c) Small Trucks

33

d) Large Buses

e) Minibuses

f) Microbus

g) Utility Van

h) Car

i) Auto-rickshaw

j) Motor Cycle

3.4.2 Video Traffic Count

In order to be able to develop an in depth understanding of current public transport demand and

use pattern in the survey area, a detailed traffic survey needs to be carried out at selected points.

The data items required to be gathered from the survey include classified vehicle counts,

estimates of passenger occupancy of all passenger vehicles estimates of bus and minibus

capacities, and route number of all bus and minibuses. However, long distance buses and

minibuses may be excluded from detailed estimates. The survey might be conducted at where

traffic flow is affected by abnormal conditions such as accidents. The video traffic survey was

conducted near the km 15+500 at Water Board Pump Station as shown above in Figure 3.7. The

results of the survey were recorded on printed forms, which helped a lot and worked as check

list. It was easy to under stand the items were to be examined during the inspection and so

reduced the possibility that significant information was omitted. Details of recorded data are

shown in Appendix-B. Comparison of hourly volume of heavy truck and all other motorized

vehicles and percentage of trucks are shown Figure 3.8 & 3.9 respectively.

34

Figure-3.8

Hourly volume of heavy truck and all other motorized vehicles on one lane from Katchpur to

Tarabo

35

Figure-3.9

Percentage of trucks and other motorized vehicles

36

3.5 METHODOLOGY OF MEASURING OF SURFACE DISTRESSES

OF BITUMINOUS SURFACE

Detailed condition surveys of the 10 km stretch were carried out. Before the detailed surface

condition was carried out the section permanently marked into blocks of 200 meters length. The

length of block some places reduced if the road was severely distressed. During the detailed

surface condition survey the nature extent severity and position of the following defects was

recorded.

1. Potholes

2. Edge beak

3. Cracking

4. Rutting

5. Depressing

6. Raveling

The detailed surface condition survey was carried out by a team of skilled labour and one

support vehicle with driver. The whole survey work was supervised by the author. The team size

was able to complete the survey work in two days. A safe working environment was maintained

at all times. Any work close to moving traffic has potential dangers. There may be legal

obligations on the part of the survey organizers in respect of safety; these must be established

and adhered to. The briefing on traffic safety precautions was given to the all survey staff before

start of the job. Area was marked in block to measure the distress of the surface. The safety

precautions were taken during the survey works are as follows:

Before work starts, warning signs, barriers and cones were placed around the work area. Work

was carried out on one side of the road at a time allowing traffic to pass on the other. Signs were

placed in the following order.

1. `Men working’ signs was placed 100 meters in front of the work area.

2. `Road narrows’ signs was placed 50 meters in front of the work area.

3. `Keep left’ arrows was placed at the start of the work area.

4. `Barriers’ was placed at each end of the work area.

5. `Keep left’ arrows was placed next to the barriers.

37

6. `Cones’ were placed in a taper at the approaches to the work area and at a spacing of 10

meters along the middle of the road next to the work area.

7. `Two flag man’ deputed to control the traffic on both end of work area.

8. `The approval of the police may be required for any activity on the highway, and their

permanent presence may be necessary for some types of survey. However, as far as

possible, the police must be made aware that there should be no unusual police presence

or activity in the survey area which could affect the traffic characteristics being measured

in the survey (for example, additional enforcement of speed limits). The verbal approval

has been taken form RHD and informed the police.

Pavement Cracks: The cracks area was marked in blocks and measured with a scale. The

cracks were measured multiplying length in meter of cracking. Only one type of cracks that

greater in number on a particular location of the pavement were measured for assessment. The

unit of measurement is square meter. The details of measurements are shown in Appendix-B.

Potholes: Potholes are structural failures which include both the surfacing and road base layer.

They are usually caused by water penetrating a cracked surfacing and weakening the road base.

Further trafficking causes the surfacing to break up and pothole develops. Measurement of

standard size of a pothole is 0.3 mm x 0.3 mm x 10 cm. The unit of measurement was number

and recorded in the form. Details are shown in Appendix-B

Depression: Localized depressions, caused by settlement of the pavement layers, construction

faults and differential movement at structures, particularly culverts, was checked. These are easy

to see after periods of rain as they take longer to dry than the rest of the road. When the road is

dry, they can also be identified by the oil stains that occur where vehicles cross the depression.

The depth was measured using the 2 meter straight-edge and wedge. Depression was measured

in terms of area. Details are shown in Appendix-B

38

Rutting: The width of the running surface and the traffic flow govern the number of observable

wheelpaths on paved roads. For example, a 3- meter carriageway will have two wheelpaths but a

at road widths greater than 6.5 meters there are generally four. At intermediate widths and low

traffic flows there is the possibility of three wheelpaths, with the central one being shared by

traffic in both directions. It was observed on the pavement that cracks appeared on both side of

centre line of road which indicated that the central one being shared by traffic in both directions

sometime. The straight edge is placed across the wheelpath, at right angles to the direction of

traffic and the maximum rut depth was recorded and found that it is less than 40 mm deep. The

calibrated wedge was used to measure the rut and found that there is no major rutting on the

road surface. The width of damage portion multiplied by its length is measured for calculating

area of rutting. Rutting of less than 5 mm depth was not considered. No rutting observed on the

said stretch. Details are shown in Appendix-B

Broken DBST Shoulder: Shoulder failures are caused by poor shoulder maintenance that

leaves the surface of the road pavement higher than the adjacent shoulder. The unsupported edge

can then be broken away by traffic, narrowing the running surface of the road. Shoulder failures

were recorded when the vertical step from the surfacing to the shoulder is greater than 50mm. It

was convenient to measure the defects with the scale on both sides of the road. The length of the

road affected was recorded on the form. The extent of edge break in meter is assessed as the

percentage of the total edge length displaying significant edge break. Details are shown in

Appendix-B

Method of rating of pavement condition: Pavement conditions were rated as good, fair, poor

and bad on the basis of visual road condition survey of the road. Marks are assigned for such

rating of the condition. The total score for rating the condition of road is appended in the

following Table-3.3

Table-3.3 Condition of road and score for rating

Condition of Road Total Score for Rating

Good 7-10

Fair 11-16

Poor 17-24

Bad > 24

It is observed that the condition of road is coming under fair category i.e. score of rating 11-16.

Assessment was made by four Engineers independently and than fixed the rating.

39

Method of rating of Surface Distress: Road condition is determined by total count (score for

rating). Total count is summation of marks scored for each type of surface distress (defect) that

observed in the pavement during visual condition survey.

Marks allotted for Different types of Surfaces Distresses: Each of surface distresses will be

assigned 1 (one) mark if the quantity is within the range shown against each on right hand side.

The following surveys conducted as per Highway Development and Management 4 (HDM4)

and as per procedure adopted by RHD.

Potholes < 1%

Broken Edges < 1%

Delamination Nil

Cracking < 2.5%

Wheel Track Rutting < 2.5%

Depression < 1%

Raveling < 1%

Figure 3.10 Picture shows surface distresses at Ch. 17+100 km

Each surface distresses will be assigned 2 (two) marks if the quantity is within the range shown

against each on right hand side.

To Sylhet

40

Potholes 1% - 5%

Broken Edges 1% -15%

Delamination < 1%

Cracking 2.5% -12.5%

Wheel Track Rutting 2.5% - 5%

Depression 1% - 5%

Raveling 1.5% - 7.5%

Figure 3.11 Picture shows surface distresses at Ch. 18+100 km

Each surface distresses will be assigned 3 (three) marks if the quantity is within the range shown

against each on right hand side.

Potholes 5% - 15%

Broken Edges 15% -30%

Delamination 1% - 5%

Cracking 12.5% -25%

Wheel Track Rutting 5% -15%

Depression 5% - 15%

Raveling 7.5% - 15%

To Sylhet

41

Figure 3.12 Picture shows surface distresses at Ch. 20+100 km

Each surface distresses will be assigned 4 (four) marks if the quantity is within the range shown

against each on right hand side.

Potholes > 15%

Broken Edges > 30%

Delamination > 5%

Cracking > 25%

Wheel Track Rutting >15%

Depression > 15%

Raveling > 15%

Figure 3.13 Picture shows surface distresses at Ch. 15+100 km

To Sylhet

42

CHAPTER 4

RESULTS AND DISCUSSION

4.1 INTRODUCTION

Condition of pavement both structurally and from the point of view of surface characteristics

were studied in this investigation. Surface conditions were checked in shape of cracks surface

distress and the deflection for measuring pavement under the action of moving loads. The

investigation of pavement and results are discussed in the following sections of this chapter.

4.2. COLLECTION OF CORE SAMPLES

Four core samples were collected from site at Ch.15+000 km to 17+000 km and tested in the

laboratory. The cores were carefully measured and the overall density of the cores, AC content,

air voids, flow and stability were determined

Figure 4.1 Picture shows four sample of cores collected from site Ch.15+100 km to 17+200 km

The properties corresponding to collected samples bituminous contents are summarized in Table

4.1 together with project specification limits for AC wearing course mix.

43

Table 4.1 Test results of cores

Name of Test Unit Sample Nos. RHD Project

Specification

Wearing Course Core 1

15+100

Core 2

17+200

Core 3

16+100

Core 4

16+600

Stability

(Marshall)

(AASHTO T245)

KN

19.74

30.44

26.94

24.65

8.2

Minimum

Flow

(Marshall)

(AASHTO T245)

mm

3.9

3.2 3.8

3.9

2-4

Air voids

In Mix

(Calculation)

%

1.05

1.72

3.29

5.93

3-5

Bitumen Content

(as % weight of

total mix)

%

5.27

4.89

5.16

5.09

5-6

For all samples taken, the asphalt concrete satisfies the minimum requirement for marshal

stability (8.2) and flow values (2-4) are also within the range as specified in the project

mentioned in the above Table 4.1. However value of air voids were ranges from 1.05 to 5.39

which is lower side and higher side mentioned in the project specification except in core no. 3.

The bitumen content of asphalt concrete in surface course varies, which is lower the side of as

specified value of mix (5% to 6%). Evaporation of volatiles present in bitumen will result in low

bitumen content. The bitumen content in asphalt concrete is about 0.5% less than the approved

design mixes. The percentage of air void in asphalt concrete is ranging from 1.05 to 5.39. Air

voids in asphalt at higher side is prone to rapid oxidation and age hardening and has high

potential for distress and premature failure.

Low Benkelman deflection and less rut depth measurement have been recorded and indicating

relatively strong foundation in the road section. The cracking of pavement and subsequently

distress has been due to the presence of significant number of heavily laden 2 axle trucks.

Substantial number of heavily loaded trucks carrying steel, stone/aggregate, food grains and

other commodities and large size buses use the road section and that the volume has been

increasing day by day. There is no provision of taking axle load measurement. Road was open

for traffic in May 2004. Thickness of AC layer is 60 mm only. Life expectancy of 60 mm AC

44

layer is assumed to be 5 years as per assumption used in HDM. Thinner AC layers are one of the

causes of pavement distress. Thinner AC layer are more vulnerable to top down cracks.

Bensalem, (2000) stated that decreasing the thickness of the AC layer results in increasing the

load induced shear strains. Hence, thinner AC layer are more vulnerable to cracks. Excessively

high vehicle loads on weak pavement certainly resulting in produced high tensile and shear

stresses in pavement, thus causing cracks and premature distress in the relatively thin asphalt

concrete surfacing.

4.3. FLOW CHARTS

A method of establishing the probable causes of pavement deterioration is given in the flow

chart shown in Figure- 4.2 to 4.4 ORN-18 (Transport Research Laboratory, UK, Overseas Road

Note 18, 1999). These charts will not cater for all the types and stages of pavement deterioration.

In particular, when a road has received a series of maintenance treatments or when the initial

deterioration is masked by further progressive failures, the problem of identifying the initial

cause of failure becomes more complex. However, the charts do provide a framework that

enables highway engineers to develop their own pavement evaluation skills. The charts identify

general causes of deterioration but do not attempt to establish specific material problems, as this

can only be done by further destructive sampling and subsequent laboratory testing.

45

Figure-4.2

46

Figure-4.3

47

Figure-4.4

48

4.4 CALCULATION FOR DESIGN OF OVERLAY

A number of deflections reading (n) were recorded during the Benkelman beam test. The mean

(x) and standard deviation ( ) are calculated.

The characteristic deflection was taken mean plus two standard deviations.

Thus,

x = n

x ................ (4.1)

=

2

1

n

xx ................. (4.2)

∆0 = x + 2 .................. (4.3)

x = arithmetic mean of measurement of deflection

= standard deviation

∆0 = Characteristics deflection

Table-4.2 Allowable Deflections as per Most Research Project R-6, (Indian Highway, May

1992, New Delhi).

Design traffic in the

(Mil. Standard Axles

Allowable Deflection

(mm)

Upto 2 1.00

2-10 0.80

10-30 0.75

>30 0.70

If the characteristic deflection is greater than the allowable deflection, the thickness of the

overlay is then determined by the following formula.

h = R log10 ∆0/∆ ................. (4.4)

where h = thickness of granular overlay in mm

∆0 = characteristic deflection

∆ = allowable deflection

R = constant, whose value taken as 550

h = 25 mm

The detail calculations of thickness of granular overlay are shown in Appendix C.

49

Yoder E. J. and Witczak M. W. et.el., (1975) presented procedure to calculate the overlay on the

existing flexible pavement. The design of overlay on the said stretch considering traffic data is

as follows. Detail of traffic data shown in Appendix D

Average gross weight of heavy trucks = 40, 000 lbs

Number of trucks in design lane = 1500 trucks

Traffic growth = 10% per year

Evaluated deflection = 0.043 inch

Figure-4.5 Asphalt concrete overlay thickness required to reduce pavement deflection from a

measured to a design deflection value. (From The Asphalt Institute)

50

Figure-4.6 Traffic analysis Chart (From The Asphalt Institute)

51

Table 4.3 Initial Traffic Number Adjustment Factorsa

Design

Period, Annual Growth Rate (percent) (r)

(yr)

(n) 0 2 4 6 8 10

1 0.05 0.05 0.05 0.05 0.05 0.05

2 0.10 0.10 0.10 0.10 0.10 0.10

4 0.20 0.21 0.21 0.22 0.22 0.23

6 0.30 0.32 0.33 0.35 0.37 0.39

8 0.40 0.43 0.46 0.50 0.53 0.57

10 0.50 0.55 0.60 0.66 0.72 0.80

12 0.60 0.67 0.75 0.84 0.95 1.07

14 0.70 0.80 0.92 1.05 1.21 1.40

16 0.80 0.93 1.09 1.28 1.52 1.80

18 0.90 1.07 1.28 1.55 1.87 2.28

20 1.00 1.21 1.49 1.84 2.29 2.86

25 1.25 1.60 2.08 2.74 3.66 4.92

30 1.50 2.03 2.80 3.95 5.66 8.22

35 1.75 2.50 3.68 5.57 8.62 13.55 a From the Asphalt Institute

Initial Traffic Number Adjustment Factor = r

nr

20

1)1(

where r = annual growth rate

n = design period (taken 6 years)

The traffic value is determined on the basis of an Initial Traffic Number ITN. From chart Figure

4.6 the ITN is estimated to be 1000. ITN value represents the daily number of (N18) load

repetitions on the design lane. As such (N18) was found to be correlated to the single axle load

limit. Average gross weight of heavy trucks and number of heavy trucks are taken from traffic

data (daily average on the design lane). The ITN determined by the above method represents the

(DTN) for the first year. In order to accounts for the (DTN) the ITN has to be multiplied with

the Initial Traffic Number Adjustment Factors which was established by the Asphalt Institute

(Asphalt Institute, MS-2,1969): The ITN was determined through monograph which is shown in

Figure 4.6. The DTN to be used is found to be (for 10% growth).

DTN = 1000 (0.39) = 390

Once the DTN is obtained, then the required overlay for 6 years from Figure 4.5 is found to be

equal 2 inch = 50 mm

52

Description of Treatments

The Highway Development and Management (HDM) analysis considers a number of treatments

representing the most commonly used types of maintenance work items in Bangladesh. Table

4.4 provides details of these treatments and the assumptions made for HDM.

Table 4.4 Maintenance and rehabilitation treatments and assumptions used in HDM

Routine

Maintenance:

Off-pavement

works:

Includes all regular works along a road such as

maintaining shoulders, roadside vegetation control,

cleaning side drains and pipe culverts, maintenance of

signs and signals.

Patching Repair of potholes based on a standards pothole unit of

0.01m3 per pothole. The quantity of pothole repairing

shall not be more than 1% of the total surface.

Cracking Sealing Sealing to cracks using Seal Coat/Fog Seal. It assumes a

maximum in any one kilometer of 5% area affected.

Periodic

Maintenance:

Preparatory Patching Patching potholes and regulating surface irregularities

prior to undertaking the treatments like DBST or DBS

Overlay. Should not be more than 2% of the total

quantity of overlay for National roads and maximum of

5% for Regional roads.

Preparatory Edge

Repair

Allows for restoring pavement edges that have been

damaged by vehicles leaving the road to drive onto the

shoulder prior to undertaking the treatments like DBST

or DBS Overlay.

DBST Applying two layers of surface treatments on the

prepared road surface. The total thickness has been

specified as 25 mm. This is applied in medium to highly

trafficked road. Life expectancy assumed to be 3 years.

Bituminous

Carpeting

This is a 40 mm thick manual overlay used in low

trafficked roads in place of dense bituminous overlay.

Life expectancy has been taken as 2 to 4 years.

Overlay Machine laid premixed dense bituminous surfacing

overlay 50-80 mm thick used in medium to highly

(Contd...)

53

Table 4.4 Maintenance and rehabilitation treatments and assumptions used in HDM

trafficked roads. Carefully controlled overlay may be

applied in response to badly damaged road surface or

high roughness so as to obtain a predefined roughness

level (2.5 to 3 IRI). Life expectancy assumed to be 5

years.

Rehabilitation Partial

Reconstruction

Reconstruction of the upper pavement layers following

scarification of the existing damaged surface and re-

compaction. Normally a 150-200 mm crushed aggregate

base with a dense bituminous surfacing of between 75

and 195 mm, depending on traffic level. This is a

treatment to overcome higher roughness or higher levels

of surface cracking resulting from delayed maintenance.

Life expectancy should be 10 years prior to major

periodic maintenance. Full design of the pavement must

be undertaken prior to treatment. Shoulder rehabilitation

would also be provided where necessary.

Complete

Reconstruction

A major reconstruction on the existing alignment and

within the same overall dimension limits. The road is not

widened. The pavement must be fully designed prior to

construction and shoulder rehabilitation provided where

necessary. Life expectancy should be 10 years before

major periodic maintenance. Applied where there are

extremely high levels of roughness and extensive

cracking.

Holding

Treatment

DBST triggered when rehabilitation is required but

budget constraints do not permit the preferred treatment.

Expected to last for 3 years.

54

4.5 PAVEMENT CONDITION ASSESSMENT

The following three methods were adopted for assessment of pavement condition and design the

overlay

1. It is noted that the cracks intensity and width of cracks are more than 3 mm in stretch of

Ch.15+000 km to 16+000 km, Ch. 20+000 km to 21+000 km and Ch.24+000 km to 25+000 km

which shows that the said stretch has been deteriorated. The thickness of said stretch has been

calculated based on intensity of the cracks. Road condition survey has been carried out and

details shown in Appendix B. It is observed that the crack range percentage was more than 25%

in the stretch of Ch.15+000 km to 16+000 km, Ch. 20+000 km to 21+000 km and Ch.24+000

km to 25+000 km. Highway Development and Management (HDM) circle of Roads and

Highways Department, Bangladesh has developed the compound maintenance standards for

National Corridor Roads to determine the overlay thickness based on intensity of the cracks

which is summarized in Table 4.5. The thickness of overlay is determined in the above stretches

25 mm.

Rating of pavement conditions was assessed based on marks allotted for different types of

surface distresses. It is observed that rated condition of road is considered fair i.e. score of rating

11 to 16. Pavement conditions were rated as good, fair poor and bad on the basis of visual

condition survey of the road. Details are shown in Table 4.7. Assessment was made by four

Engineer independently and than fixed the average rating road condition. Table 4.4 shows the

compound maintenance standards adopted for Highway Development and Management (HDM)

analysis for the different classes of roads. These standards are based on experience and analysis

of road conditions in Bangladesh, and considered to be reliable bases for HDM-4 to estimate

economic performance of the network. Final treatment design must be separately established.

55

Table 4.5 Compound maintenance standards for national corridor roads and assumption used in

HDM.

Compound Maintenance Standards for National Corridor Roads

Roughness

Range

(IRI)

Cracking

Range

(%)

Traffic Range (MT – AADT)

100-1919 2000-3999 4000-5999 6000-9999 > 10000

< 4.0

<25% Routine

> = 25% DBST 25 mm Overlay

50 mm

4.00 - <

7.00 All

Overlay 50 mm

Overlay

50 mm

Overlay

80 mm

7.00 <

9.00 All

Overlay

60 mm

Overlay

80 mm

9.00 <

12.00 All

Rehab

120 mm

Rehab

140 mm

Rehab

150 mm

Rehab

180 mm

Rehab

195 mm

> 12.00 All Full Rec

120 mm

Full Rec

140 mm

Full Recon

150 mm

Full Recon

180 mm

Full Recon

195 mm

Range of cracking measured which is shown in Table 4.6. Cracking range compare with total

area and calculated the percentage.

Table 4.6 Cracking range percentage Chainage

(Km)

Total Area

of Surface

(m2)

Area Cracks

>3 mm

(m2)

Cracking

Range

%

Possible Causes Remarks

15+000 to 16+000 7300 3700 50%

- Insufficient AC

thickness (60 mm)

- Aging and traffic load

- Initial deterioration

on the AC layer is

the result of thermal

stresses

- Due to bus stand

16+000 to 17+000 7300 - -

- Insufficient AC

thickness (60 mm)

- Aging and traffic

load

- Initial deterioration

on the AC layer is the result of thermal

stresses

- Transverse thermal

cracks progress

- Fatigue cracking

begins as single

longitudinal

cracks in the wheel path thickness is

<1mm

17+000 to 18+000 7300 60 .008%

- Insufficient AC

thickness (60 mm)

- Aging and traffic

load

- Initial deterioration

on the AC layer is

the result of thermal

stresses

- Transverse thermal

cracks progress

- Fatigue cracking

begins as

single longitudinal

cracks in the wheel

path thickness is

<1mm

18+000 to 19+000 7300 30 .004%

- Insufficient AC

thickness (60 mm)

- Aging and traffic load

- Initial deterioration

on the AC layer is

- Transverse thermal

cracks progress

- Fatigue cracking begins as single

longitudinal

cracks in the wheel

(Contd...)

56

Table 4.6 Cracking range percentage Chainage

(Km)

Total Area

of Surface

(m2)

Area Cracks

>3 mm

(m2)

Cracking

Range

%

Possible Causes Remarks

the result of thermal

stresses

path thickness is

<1mm

19+000 to 20+000 7300 50 .006%

- Insufficient AC

thickness (60 mm)

- Aging and traffic load

- Initial deterioration

on the AC layer is

the result of thermal

stresses

- Transverse thermal

cracks progress

- Fatigue cracking begins as single

longitudinal

cracks in the wheel

path thickness is

<1mm

20+000 to 21+000 7300 1950 26.7%

- Insufficient AC -

In sufficient of AC

thickness (60 mm)

- Aging and traffic

load

- Initial deterioration

on the AC layer is the result of thermal

stresses

21+000 to 22+000 73000 1700 23.28%

- Insufficient AC

thickness (60 mm)

- Aging and traffic

load

- Initial deterioration

on the AC layer is

the result of thermal

stresses

- Due to bus stand

22+000 to 23+000 73000 300 .004%

- Insufficient AC

thickness (60 mm)

- Aging and traffic load

- Initial deterioration

on the AC layer is

the result of thermal

stresses

- Transverse thermal

cracks progress

- Fatigue cracking begins as single

longitudinal

cracks in the wheel

path thickness is

<1mm

23+000 to 24+000 73000 150 .002%

- Insufficient AC

thickness (60 mm)

- Aging and traffic

load

- Initial deterioration

on the AC layer is

the result of thermal stresses

- Transverse thermal

cracks progress

- Fatigue cracking

begins as single

longitudinal

cracks in the wheel

path thickness is <1mm

24+000 to 25+000 73000 1850 25.3%

- Insufficient AC

thickness (60 mm)

- Aging and traffic

load

- Initial deterioration

on the AC layer is

the result of thermal

stresses

57

Table 4.7 Qualitative descriptors of IRI values

Condition of Road National Highway

Good 0-3.9

Fair 4.0-5.9

Poor 6.0-7.9

Bad 8.0-9.9

Very bad 10

2. Benkelman Beam test carried out on 25 nos. location in 10 km stretch to check the

structural performance of the highway. The deflection observed was less than 1 mm in

Ch.16+000 km to 20+000 km and Ch.23+000 km to 25+000 km which shown the good strength

of the existing pavement. The deflection value in Ch.15+000 km to 16+000 km and Ch.21+000

km to 23+000 km was found more than 1 mm which shows less strength of existing pavement

compared to other area of stretch. Evaluated deflection values are shown in Figure 4.9. The tests

were carried out at 200 m interval in the stretches Ch.21+000 km to 23+000 km to know more

accurate results. The thickness of the overlay calculated based on the deflection values and it is

determined 25 mm in the stretches Ch.15+000 km to 16+000 km and Ch.21+000 km to 23+000

km. Details are shown in Appendix A and Appendix C.

3. The traffic count has been carried out and checked the adequacy of the pavement

structure for present day traffic loading. Traffic data of last year collected from RHD

Bangladesh and calculated the growth rate. Growth rate of traffic found from data is 10%,

Asphalt Institute has developed the design chart shown in Figure 4.5 and Figure 4.6. The traffic

value is determined on the basis of an ITN and from chart Figure 4.6 the ITN is estimated 1000.

The deflection value calculated by Benkelman beam test is obtained 0.043 inch. The road was

opened for traffic in May, 2004 and 6 year period was considered to check the pavement present

position against the traffic load. After applying the initial traffic number adjustment factor for

design period of 6 years. The required overlay for 6 year is found 50 mm.

58

Figure-4.7

Showing evaluated deflection values

59

4.6 FIELD OBSERVATIONS AND PHOTOGRAPHS

The survey locations characteristic are shown in the Figure 4.8 to Figure 4.13. It is observed

from the sites surveys that the single longitudinal cracks in the wheel path have developed in

some reaches. The cracks indicate fatigue failure of the asphalt layer generally caused by

repeated traffic loading and distress allows water to penetrate the surfacing material and sub

grade which furthers the damage. Alligator cracking also called fatigue cracking usually first

begins as a single longitudinal crack in the wheel path. Top down cracks (TDC) are longitudinal

and transverse cracks that initiated at the pavement surface and propagate downward. They have

been increasing and observed in pavement throughout the 10 km reach. TDC are usually

manifested as longitudinal cracks appearing just outside the wheel paths. Over time, they form

an extensive network of longitudinal cracks connected by short transverse cracks, which

ultimately reduce the life of the pavement.

Figure 4.8 Picture shows the failure occurred in the centre of the pavement at Ch. 15+300 km

Closely spaced inter connecting cracks are referred to as crocodile cracks. As there is no rutting,

the most likely causes are poor construction of the surface layer, aging and traffic load. If the

cracking is identified early, the crack should be sealed. The cracking has developed and is

extensive; the length of road should be surfaced with Asphalt.

To Sylhet

60

Figure 4.9 Minor single longitudinal cracks in the wheel path has begins at Ch. 16+100 km

The small cracks appear on the surface which is observed during the monitoring. These should

be sealed immediately. Continuing deformation show that the road is not strong enough and

overlay may be required.

Figure 4.10 Picture shows the failure occurred in the centre of the pavement at 17+300 km

Closely spaced inter connecting cracks are referred to as crocodile cracks. As there is no ratting,

the most likely causes are poor construction of the surface layer aging and traffic load. If the

cracking is identified early, the crack should be sealed. The cracking has developed and is

extensive; the length of road should be surfaced with Asphalt.

To Sylhet

To Sylhet

61

Figure 4.11 Picture shows the failure occurred in the centre of the pavement as well as at the pavement

edge at Ch.18+600 km

Figure 4.12 Picture shows the failure occurred in the centre of the pavement as well

as at the pavement edge. The failure also occurred around the round about at Ch. 24+200 km

Cracks occurred around the round about due to tyers place high lateral forces on the surface. The

damaged material should be removed and overlay may be placed.

To Sylhet

To Sylhet

62

Figure 4.13 Picture shows the failure occurred in the centre of the pavement as well as

at the pavement edge. The failure also occurred around the round about at Ch. 24+200 km

4.7 SUMMARY

Prepared the road inventorying and also carried out the deflection test to check the strength of

existing pavement and designed the overlay for strengthening of existing pavement.

Similar research has been done in RHD, Bangladesh. This study was carried out to evaluate the

pavement surface conditions and identified possible causes and maintenance measures of those

defects for Road Rehabilitation and Maintenance Project (RRMP-2, 1994).

To Sylhet

63

CHAPTER 5

CONCLUSIONS AND RECOMMENDATIONS

5.1 CONCLUSIONS

Based on the deflection value, cracks and traffic volume, its interpretation and evaluation, the

following conclusions are drawn:

i) Presence of significant number of grossly and illegally overloaded vehicles, particularly

2 axle trucks, resulted high tensile and shear stress in the thin AC wearing course (60

mm only) causing in distress of the pavement. Thicker asphalt concrete layers resists

excessive deformation under large traffic volume upto some extent and prolong life of

the pavement.

ii) Based on the HDM 4 and experience a compound maintenance standard for national

corridor roads is fixed by the Roads and Highways Department, Bangladesh. The

minimum thickness of overlay required is DBST of 25 mm on the stretches of Ch.

15+000 km to 16+000 km, Ch.20+000 km to 21+000 km and Ch.24+000 km to 25+000

km where cracking range is more than 25%. Remaining stretch would be repaired by

sealing the cracks where cracking range is less than 25%.

Table 5.1 Determined overlay based on cracking range percentage

Chainage

Km

Determined Overlay

mm

Percentage cracking range >

3 mm

15+000 km to 16+000 km 25 mm thick DBST 50%

20+000 km to 21+000 km 25 mm thick DBST 26.7%

24+000 km to 25+000 km 25 mm thick DBST 25.3%

iii) Based on deflection values the thickness of overlay required is 25 mm DBST in the

stretches Ch.15+000 km to 16+000 km and Ch. 21+000 km to 23+000 km.

Table 5.2 Design overlay based on deflection value

Chainage

Km

Designed Overlay

mm

Average deflection value

mm

15+000 km to 16+000 km 25 mm thick DBST 1.2

21+000 km to 23+000 km 25 mm thick DBST 1.2

iv) Based on the traffic data the thickness of the overlay required is 50 mm. The road was

opened for traffic in 2004. Six year period was considered for calculation of overlay for

which an overlay of 50 mm is required.

64

Table 5.3 Design overlay based on traffic data

Chainage

Km

Designed Overlay

mm

Volume of heavy trucks on design lane Nos.

15+000 km to 25+000 km 50 mm 1500

5.2 RECOMMENDATIONS

In view of the observation made from this research work, the following recommendations are

made:

1. Based on the investigation and observation it is found that there is structural deficiency

in the existing pavement. Although only part of 10 km stretch of the road pavement has

shown deterioration, but eventually it will affect all AC wearing course of 10 km as the

process will likely to continue unless necessary remedial measure is urgently taken up.

An AC overlay of minimum 100 mm is required to strengthen the pavement but only 60

mm thick AC wearing course provided during construction. So to make up the

deficiency, it is essential to provide a surface course of 50 mm to be executed

immediately. The life expectancy will be 5 years. Thorough repair of the existing

pavement would be required before placing the overlay.

2. It is observed that the exceptionally heavily loaded trucks are present in the roads

network, although the legal limit of axle load in Bangladesh is 10 tonnes only. It is

essential that law enforcement agencies should implement strict control over the increase

in vehicle axle load. It is required to control the overloaded trucks which result in saving

in road maintenance and rehabilitation.

3. It is also recommended that a comprehensive axle load and traffic survey be taken under

on the National and Regional Roads to establish the necessary data base for road design

and maintenance planning purpose. To control overloading weigh bridges are required to

installed at strategic points of the major roads network.

4. The use of a 60/70 penetration grade bitumen instead of 80/100 penetration grade in

asphalt concrete seems to be more appropriate for Bangladesh climatic condition. It is

also better to add some filler like lime of 1% to 2% in AC mixes produced with

aggregate which will increase the resistance to adverse effect of water.

5. Rigid pavement for certain length may be provided over the area of bus bays.

65

References

1. Rolt J, Hasim M S Hameed M and Suffian Z “The prediction and treatment of

reflection cracking ill thin bituminous overlays”. Second Malaysian Road Conference

1996, Kuala Lumpur.

2. Dickinson E J. “Bituminous roads in Australia. Australian Road Research Board”,

1984.

3. Smith H. R., Rolt J, and Wambura, J. “The durability of bituminous overlays and

wearing courses in tropical environments”. 3rd Conf. The Bearing Capacity of Roads

and Airfields. Trondheim, 1990.

4. Rolt J, Smith H R and Jones C R “The design and performance of bituminous

overlays in tropical environments”. 2nd Conf. The Bearing Capacity of Roads and

Airfields, Plymouth, 1986.

5. Paterson, W. D. O., “Road deterioration and maintenance effects: models for planning

and management”. Highway Design and Maintenance Series. The John Hopkins

University Press, Baltimore, Maryland.1987.

6. Smith, H. R., and Jones, C. R. , “Measurement of pavement defections ill tropical and

sub-tropical climates.” Laboratory Report LR 935. Transport Research Laboratory,

Crowthorne, 1980.

7. Khana, P. N., “Handbook of Civil Engineering”, Engineer’s Publisher’s, New Delhi,

1992.

8. Joe, W. B., “Summary of Asphalt additives Performance at selected Sites.”

Transportation Research Board, TRR-1342, 1991. pp.67-75

9. Warden, W. B., Hudson, S. B., and Howell, H. C., “Evaluation of Mineral Filler in

Terms of Practical Pavement performance” AAPT, Proc. 28, 1959, PP. 97-125

66

10. Yoder, E. J., and Witzak, M.W., “Principals of Pavement Design”, Second Edition,

Part V Pavement Evaluation and Rehabilitation 1975.

11. The Asphalt Institute, “Asphalt Overlays and Pavement Rehabilitation,” MS. 17,

1969.

Time

Start Initial Dial Reading (A)

Final Dial Reading (B)

(A-B) x 100 (A-B) x BR Air (C)

Pavement (C)

(7)- (10) Average

1 2 3 4 5 6 7 8 9 10 11 12 1314+500 R 2.30 PM 3.00 2.54

2.432.39 54 108 31 36 0.0065 1.08

3.00 2.552.452.41 53 106 31 36 0.0065 1.06 1.07

15+000 R 3.02 PM 3.00 2.632.572.54 42 84 31 35 0.00 0.84

3.00 2.612.562.53 43 86 31 35 0.00 0.86 0.85

15+500 R 3.36 PM 3.00 2.662.612.60 37 74 32 35 0.00 0.74

3.00 2.702.642.60 35 70 32 35 0.00 0.70 0.72

APPENDICESAppendix-A: Details of Measurement of Deflection of Pavement Checked by Benklman Beam Test

Test Location

(Chainage)

Wheel Path Left/Right

(L/R)

Temperature Correction

Value

Corrected Deflection (MM)

Remarks

Rear Axle Load: 8.2 Tonne

Deflection Reading Deflection Temperature

Sheet: 01

Road: N-2- Dhaka-SylhetTyre Pressure: 5.6 kg /cm2

Dial Gauge: 0.01 mmBeam Ratio (BR) : 1: 2Technician/Operator Name: Md. Iqbal Hossain

Date: 07.06.2009

67

Time

Start Initial Dial Reading (A)

Final Dial Reading (B)

(A-B) x 100 (A-B) x BR Air (C)

Pavement (C)

(7)- (10) Average

1 2 3 4 5 6 7 8 9 10 11 12 1316+000 R 4.04 PM 3.00 2.63

2.602.58 39 78 32 36 0.0065 0.779

3.00 2.652.612.57 39 78 32 36 0.0065 0.779 0.779

16+500 R 4.30 PM 3.00 2.602.552.50 45 90 32 36 0.0065 0.0.899

3.00 2.632.532.48 45 90 32 36 0.0065 0.899 0.89

17+000 R 5.00 PM 3.00 2.692.622.59 36 72 34 36 0.0065 0.719

3.00 2.722.652.61 34 68 34 36 0.0065 0.679 0.699

Technician/Operator Name: Md. Iqbal Hossain Beam Ratio (BR) : 1: 2Rear Axle Load: 8.2 Tonne

Appendix-A: Details of Measurement of Deflection of Pavement Checked by Benklman Beam Test

Sheet: 02

Date: 07.06.2009 Tyre Pressure: 5.6 kg /cm2

Road: N-2- Dhaka-Sylhet Dial Gauge: 0.01 mm

RemarksDirection Reading Deflection TemperatureTest Location

(Chainage)

Wheel Path Left/Right

(L/R)

Temperature Correction

Value

Corrected Deflection (MM)

68

Time

Start Initial Dial Reading (A)

Final Dial Reading (B)

(A-B) x 100 (A-B) x BR Air (C)

Pavement (C)

(7)- (10) Average

1 2 3 4 5 6 7 8 9 10 11 12 1317+500 R 09.40 AM 3.00 2.79

2.632.60 32 64 34 44 0.0585 0.639

3.00 2.782.702.64 29 58 34 44 0.0585 0.574 0.61

18+000 R 10.15 AM 3.00 2.712.682.60 33 66 35 44 0.0585 0.659

3.00 2.712.652.60 34 68 35 44 0.0585 0.679 0.67

18+500 R 10.45 AM 3.00 2.662.622.59 37 74 35 43 0.052 0.739

3.00 2.672.592.53 40 80 35 43 0.052 0.80 0.76

Road: N-2- Dhaka-SylhetDate: 07.06.2009 & 08.06.2009

Sheet: 03

Appendix-A: Details of Measurement of Deflection of Pavement Checked by Benklman Beam Test

Technician/Operator Name: Md. Iqbal Hossain

Tyre Pressure: 5.6 kg /cm2

Dial Gauge: 0.01 mmBeam Ratio (BR) : 1: 2Rear Axle Load: 8.2 Tonne

RemarksDirection Reading Deflection TemperatureTest Location

(Chainage)

Wheel Path Left/Right

(L/R)

Temperature Correction

Value

Corrected Deflection (MM)

69

Time

Start Initial Dial Reading (A)

Final Dial Reading (B)

(A-B) x 100 (A-B) x BR Air (C)

Pavement (C)

(7)- (10) Average

1 2 3 4 5 6 7 8 9 10 11 12 1319+000 R 11.25 AM 3.00 2.60

2.562.51 44 88 35 43 0.052 0.879

3.00 2.592.562.52 44 88 35 43 0.052 0.879 0.88

19+500 R 12.05 PM 3.00 2.612.532.48 46 92 34 42 0.045 0.919

3.00 2.642.532.49 44 88 34 42 0.045 0.879 0.90

20+000 R 12.30 AM 3.00 2.682.602.54 39 78 34 42 0.045 0.779

3.00 2.652.682.15 40 80 34 42 0 0.799 0.79

20+500 R 13.10 PM 3.00 2.672.612.59 37 74 34 42 0.045 0.739

3.00 2.642.602.57 39 78 34 42 0.045 0.779 0.76

Appendix-A: Details of Measurement of Deflection of Pavement Checked by Benklman Beam Test

Test Location

(Chainage)

Wheel Path Left/Right

(L/R)

Temperature Correction

Value

Corrected Deflection (MM)

Remarks

Rear Axle Load: 8.2 Tonne

Direction Reading Deflection Temperature

Sheet: 04

Road: N-2- Dhaka-SylhetTyre Pressure: 5.6 kg /cm2

Dial Gauge: 0.01 mmBeam Ratio (BR) : 1: 2Technician/Operator Name: Md. Iqbal Hossain

Date: 08.06.2009

70

Time

Start Initial Dial Reading (A)

Final Dial Reading (B)

(A-B) x 100 (A-B) x BR Air (C)

Pavement (C)

(7)- (10) Average

1 2 3 4 5 6 7 8 9 10 11 12 1321+000 R 13.40 PM 3.00 2.54

2.462.42 52 104 34 40 0.033 1.04

3.00 2.512.472.43 53 106 34 40 0.033 1.06 1.05

21+200 R 14.15 PM 3.00 2.532.482.46 51 102 34 41 0.039 1.01

3.00 2.512.472.46 52 104 34 41 0.039 1.04 1.03

21+400 R 14.38 PM 3.00 2.522.482.46 51 102 35 43 0.052 1.02

3.00 2.522.462.45 52 104 35 43 0.052 1.03 1.025

21+600 R 15.00 PM 3.00 2.462.422.39 57 114 35 42 0.045 1.14

3.00 2.462.432.39 57 114 35 42 0.045 1.14 1.14

Appendix-A: Details of Measurement of Deflection of Pavement Checked by Benklman Beam Test

Wheel Path Left/Right

(L/R)

Temperature Correction

Value

Corrected Deflection (MM)

Date: 08.06.2009 Tyre Pressure: 5.6 kg /cm2

Road: N-2- Dhaka-SylhetTechnician/Operator Name: Md. Iqbal Hossain

Dial Gauge: 0.01 mmBeam Ratio (BR) : 1: 2

Sheet: 05 Rear Axle Load: 8.2 Tonne

RemarksDirection Reading Deflection TemperatureTest Location

(Chainage)

71

Time

Start Initial Dial Reading (A)

Final Dial Reading (B)

(A-B) x 100 (A-B) x BR Air (C)

Pavement (C)

(7)- (10) Average

1 2 3 4 5 6 7 8 9 10 11 12 1321+800 R 15.34 PM 3.00 2.46

2.432.40 57 114 33 40 0.032 1.14

3.00 2.482.442.40 56 112 33 40 0.032 1.11 1.12

22+000 R 16.00 PM 3.00 2.432.382.36 61 122 33 39 0.026 1.22

3.00 2.452.392.36 60 120 33 39 0.026 1.20 1.21

22+500 R 16.30 PM 3.00 2.422.372.33 62 124 33 41 0.045 1.24

3.00 2.452.382.34 61 122 33 41 0.045 1.22 1.23

22+800 R 17.00 PM 3.00 2.502.472.45 52 114 32 40 0.032 1.14

3.00 2.522.482.44 52 114 32 40 0.032 1.14 1.14

Temperature Correction

Value

Corrected Deflection (MM)

Remarks

Date: 08.06.2009 Tyre Pressure: 5.6 kg /cm2

Road: N-2- Dhaka-Sylhet

Rear Axle Load: 8.2 Tonne

Appendix-A: Details of Measurement of Deflection of Pavement Checked by Benklman Beam Test

Direction Reading Deflection Temperature

Technician/Operator Name: Md. Iqbal Hossain

Test Location

(Chainage)

Wheel Path Left/Right

(L/R)

Dial Gauge: 0.01 mmBeam Ratio (BR) : 1: 2

Sheet: 06

72

Time

Start Initial Dial Reading (A)

Final Dial Reading (B)

(A-B) x 100 (A-B) x BR Air (C)

Pavement (C)

(7)- (10) Average

1 2 3 4 5 6 7 8 9 10 11 12 1323+000 R 17.30 PM 3.00 2.55

2.492.46 50 100 30 39 0.026 1.00

3.00 2.512.472.44 52 104 30 39 0 1.04 1.02

23+500 R 18.00 PM 3.00 2.522.482.43 52 104 30 39 0.026 1.04

3.00 2.502.462.43 53 106 30 39 0.026 1.05 1.04

24+000 R 18.30 PM 3.00 2.542.472.45 51 102 30 39 0.026 1.02

3.00 2.592.512.48 47 94 30 39 0.94 0.98

24+500 R 19.00 PM 3.00 2.582.542.50 46 92 30 39 0.026 0.92

3.00 2.592.542.51 45 90 30 39 0.026 0.90 0.91

Appendix-A: Details of Measurement of Deflection of Pavement Checked by Benklman Beam Test

Wheel Path Left/Right

(L/R)

Temperature Correction

Value

Corrected Deflection (MM)

Date: 08.06.2009 Tyre Pressure: 5.6 kg /cm2

Road: N-2- Dhaka-SylhetTechnician/Operator Name: Md. Iqbal Hossain

Dial Gauge: 0.01 mmBeam Ratio (BR) : 1: 2

Sheet: 07 Rear Axle Load: 8.2 Tonne

RemarksDirection Reading Deflection TemperatureTest Location

(Chainage)

73

Time

Start Initial Dial Reading (A)

Final Dial Reading (B)

(A-B) x 100 (A-B) x BR Air (C)

Pavement (C)

(7)- (10) Average

1 2 3 4 5 6 7 8 9 10 11 12 1325+000 R 19:30 AM 3.00 2.62

2.552.51 44 88 30 39 0.026 0.88

3.00 2.602.542.51 45 90 30 39 0.026 0.89 0.86

Temperature Correction

Value

Corrected Deflection (MM)

Remarks

Date: 08.06.2009 Tyre Pressure: 5.6 kg /cm2

Road: N-2- Dhaka-Sylhet

Rear Axle Load: 8.2 Tonne

Appendix-A: Details of Measurement of Deflection of Pavement Checked by Benklman Beam Test

Direction Reading Deflection Temperature

Technician/Operator Name: Md. Iqbal Hossain

Test Location

(Chainage)

Wheel Path Left/Right

(L/R)

Dial Gauge: 0.01 mmBeam Ratio (BR) : 1: 2

Sheet: 08

74

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km 5 - - 800 - - - P 75 100 P 75 80

.6 km 2 - - 800 - - - P 75 120 P 75 60

.4 km - - - 800 - - - P 75 100 P 75 120

.2km 2 - - 800 - - - P 75 100 P 75 100

.0 km 15 - - 500 - 10 - P 75 80 P 75 100

Condition paved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

4 6Depression

AreaLeftEdge BreakPotholesChainage

(Off set)Raveling

areaRegradeCracking

Side Drain

10Bituminous Pavement

12.06.2009

Right8

Shoulder Embankment

9

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP)Start Offset Start Chainage 15 Km

End: LRP End Offset End Chainage 16 Km

6

6

6

6

6

6

6

6

6

6

75

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km - - - - - - - P 100 80 P 100 60

.6 km - - - - - - - P 100 60 P 100 40

.4 km - - - - - - - P 100 30 P 100 80

.2km 1 - - - - - - P 100 20 P 100 20

.0 km - - - - - - - P 100 40 P 100 30

Condition paved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

Side Drain

10Bituminous Pavement

12.06.2009

4 6Right

8Shoulder Embankment

9LeftEdge BreakPotholesChainage

(Off set)Raveling

areaDepression

AreaRegradeCracking

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 30Start Offset Start Chainage 16 Km

End: LRP 31End Offset End Chainage 17 Km

6

6

6

6

6

6

6

6

6

6

76

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km - - - 20 - - - P 100 80 P 100 30

.6 km - - - - - - - P 100 60 P 100 20

.4 km 2 - - 30 - - - P 100 50 P 100 20

.2km - - - - - - - P 100 30 P 100 80

.0 km - - - 10 - - - P 100 20 P 100 40

Condition paved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

Edge BreakPotholesChainage (Off set)

Raveling area

RegradeCracking Depression Area

Right8

Shoulder Embankment

9Left

Side Drain

10Bituminous Pavement

12.06.2009

4 6

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 31Start Offset Start Chainage 17 Km

End: LRP 32End Offset End Chainage 18 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 30Start Offset Start Chainage 17 Km

End: LRP 32End Offset End Chainage 18 Km

6

6

6

6

6

6

6

6

6

6

77

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km 2 - - 600 - - - P 50 60 P 50 30

.6 km 1 - - 200 - - - P 50 80 P 50 20

.4 km - - - - - - - P 50 60 P 50 40

.2km - - - - - - - P 50 40 P 50 30

.0 km - - - 10 - - - P 50 20 P 50 20

Condition paved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

Side Drain

10Bituminous Pavement

12.06.2009

4 6Right

8Shoulder Embankment

9LeftEdge BreakPotholesChainage

(Off set)Raveling

areaDepression

AreaRegradeCracking

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 18 Km

End: LRP End Offset End Chainage 19 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 31Start Offset Start Chainage 17 Km

End: LRP 32End Offset End Chainage 18 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP)Start Offset Start Chainage 18 Km

End: LRP End Offset End Chainage 19 Km

6

6

6

6

6

6

6

6

6

6

78

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km - - - 30 - - - P 100 40 P 100 30

.6 km - - - - - - - P 100 20 P 100 20

.4 km - - - 20 - - - P 100 60 P 100 20

.2km - - - - - - - P 100 80 P 100 40

.0 km - - - - - - - P 100 20 P 100 20

Condition paved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

4 6Depression

AreaEdge BreakPotholesChainage

(Off set)Raveling

areaRegradeCracking

Side Drain

10Bituminous Pavement

12.06.2009

Right8

Shoulder Embankment

9Left

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 19 Km

End: LRP End Offset End Chainage 20 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 18 Km

End: LRP End Offset End Chainage 19 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 31Start Offset Start Chainage 17 Km

End: LRP 32End Offset End Chainage 18 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP)Start Offset Start Chainage 19 Km

End: LRP End Offset End Chainage 20 Km

6

6

6

6

6

6

6

6

6

6

79

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km 4 - - 750 - - - P 100 30 P 100 20

.6 km - - - 300 - - - P 100 30 P 100 20

.4 km 2 - - 750 - - - P 100 60 P 100 60

.2km - - - - - - - P 100 40 P 100 40

.0 km - - - 150 - - - P 100 80 P 100 80

Condition paved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

Side Drain

10Bituminous Pavement

13.06.2009

4 6Right

8Shoulder Embankment

9LeftEdge BreakPotholesChainage

(Off set)Raveling

areaDepression

AreaRegradeCracking

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 20 Km

End: LRP End Offset End Chainage 21 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 19 Km

End: LRP End Offset End Chainage 20 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 18 Km

End: LRP End Offset End Chainage 19 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 31Start Offset Start Chainage 17 Km

End: LRP 32End Offset End Chainage 18 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP)Start Offset Start Chainage 20 Km

End: LRP End Offset End Chainage 21 Km

6

6

6

6

6

6

6

6

6

6

80

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km 2 - - 200 - - - P 100 40 P 100 40

.6 km - - - 150 - - - P 100 50 P 100 20

.4 km - - - 500 - - - P 100 60 P 100 30

.2km 3 - - 750 - - - P 100 30 P 100 40

.0 km - - - 100 - - - P 100 20 P 100 20

Condition paved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

4 6Depression

AreaEdge BreakPotholesChainage

(Off set)Raveling

areaRegradeCracking

Side Drain

10Bituminous Pavement

13.06.2009

Right8

Shoulder Embankment

9Left

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 21 Km

End: LRP End Offset End Chainage 22 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 20 Km

End: LRP End Offset End Chainage 21 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 19 Km

End: LRP End Offset End Chainage 20 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 18 Km

End: LRP End Offset End Chainage 19 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 31Start Offset Start Chainage 17 Km

End: LRP 32End Offset End Chainage 18 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP)Start Offset Start Chainage 21 Km

End: LRP End Offset End Chainage 22 Km

6

6

6

6

6

6

6

6

6

6

81

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km - - - - - - - P 100 180 P 100 120

.6 km - - - - - - - P 100 120 P 100 100

.4 km - - - 300 - - - P 100 120 P 100 80

.2km - - - - - - - P 100 160 P 100 100

.0 km - - - - - - - P 100 120 P 100 80

Condition unpaved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

Side Drain

10Bituminous Pavement

13.06.2009

4 6Right

8Shoulder Embankment

9LeftEdge BreakPotholesChainage

(Off set)Raveling

areaDepression

AreaRegradeCracking

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 22 Km

End: LRP End Offset End Chainage 23 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 21 Km

End: LRP End Offset End Chainage 22 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 20 Km

End: LRP End Offset End Chainage 21 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 19 Km

End: LRP End Offset End Chainage 20 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 18 Km

End: LRP End Offset End Chainage 19 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 31Start Offset Start Chainage 17 Km

End: LRP 32End Offset End Chainage 18 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP)Start Offset Start Chainage 22 Km

End: LRP End Offset End Chainage 23 Km

6

6

6

6

6

6

6

6

6

6

82

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km - - - - - - - P 100 180 P 100 180

.6 km - - 100 50 - - - P 100 120 P 100 120

.4 km 2 - 500 100 - - - P 100 180 P 100 180

.2km - - - - - - - P 100 180 P 100 200

.0 km 2 - 400 - - - - P 100 200 P 100 150

Condition paved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

4 6Depression

AreaEdge BreakPotholesChainage

(Off set)Raveling

areaRegradeCracking

Side Drain

10Bituminous Pavement

13.06.2009

Right8

Shoulder Embankment

9Left

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 23 Km

End: LRP End Offset End Chainage 24 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 22 Km

End: LRP End Offset End Chainage 23 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 21 Km

End: LRP End Offset End Chainage 22 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 20 Km

End: LRP End Offset End Chainage 21 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 19 Km

End: LRP End Offset End Chainage 20 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 18 Km

End: LRP End Offset End Chainage 19 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 31Start Offset Start Chainage 17 Km

End: LRP 32End Offset End Chainage 18 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP)Start Offset Start Chainage 23 Km

End: LRP End Offset End Chainage 24 Km

6

6

6

6

6

6

6

6

6

6

83

Appendix-B: Road Condition Survey Date:

Earth Rd

1 2 3 5 7Rutting Left Right Left Right

<3 mm >3 mm Av. Depth Paved/Unpaved

Edge Step

Cond Area

Paved/Unpaved

Edge Step Cond Area

Cond Area

Cond Area

Cond Length

Cond Length

1.0 km Nos. Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m Sq. m mm Sq. m mm Sq. m Sq. m Sq. m L.m L.m

.8 km - - - 150 - - - P 75 160 P 50 120

.6 km - - 850 - - - - P 50 180 P 60 60

.4 km 3 - - 750 - - - P 50 200 P 60 140

.2km - - - 100 - - - P 50 200 P 50 140

.0 km 2 - - 850 - - - P 50 120 P 50 60

Condition paved shoulder Condition unpaved shoulder Embankment Condition Shoulder Type Drain Condition Edge Step1. Good 1. Good 1. Good P = Paved 1. Good 1. High shoulder2. Coronation 2. Cracking 2. Gullies U = Unpaved 2. Overgrown 2. Low shoulder3. Gullies 3. Raveling 3. Erosion 3. Silted4. Potholed 4. Potholes 4. Blocked5. Edge drop 5. Edge drop 5. Broken6. Width loss 6. Width loss

Side Drain

10Bituminous Pavement

13.06.2009

4 6Right

8Shoulder Embankment

9LeftEdge BreakPotholesChainage

(Off set)Raveling

areaDepression

AreaRegradeCracking

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 24 Km

End: LRP End Offset End Chainage 25 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 23 Km

End: LRP End Offset End Chainage 24 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 22 Km

End: LRP End Offset End Chainage 23 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 21 Km

End: LRP End Offset End Chainage 22 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 20 Km

End: LRP End Offset End Chainage 21 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 19 Km

End: LRP End Offset End Chainage 20 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) Start Offset Start Chainage 18 Km

End: LRP End Offset End Chainage 19 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP) 31Start Offset Start Chainage 17 Km

End: LRP 32End Offset End Chainage 18 Km

Road No.N2

Road NameDHAKA-SYLHET

Start: Location Ref Point (LRP)Start Offset Start Chainage 24 Km

End: LRP End Offset End Chainage 25 Km

6

6

6

6

6

6

6

6

6

6

84

85

APPENDIX-C: CALCULATION DETAILS

Table-4.2 Allowable Deflections as per Most Research Project R-6, (Indian Highway, May

1992, New Delhi).

Design traffic in the

(Mil. Standard Axles

Allowable Deflection

(mm)

Upto 2 1.00

2-10 0.80

10-30 0.75

>30 0.70

If the characteristic deflection is greater than the allowable deflection, the thickness of the

overlay is then determined by the following formula.

h = R log10 ∆0/∆

h = thickness of granular overlay in mm

∆0 = characteristic deflection

∆ = allowable deflection

R = constant, whose value taken as 550

x = n

x ........ (4.1)

x = 10

05.102.114.123.121.112.114.103.103.105.1

x = 1.10

=

2

1

n

xx .........(4.2)

110

10.105.110.102.110.114.110.123.110.121.110.112.110.114.110.103.110.103.110.105.12

=

9

34.032.02

= 0.006 mm

∆0 = x + 2 .........(4.3)

∆0 = 1.10+2 x .006

= 1.112 mm

h = R log10 ∆0/∆

= 550 log10 1.112/1

= 25.35 mm = 25 mm

Appendix-D: Hourly Traffic Volume Summary Sheet Date:

From To From To From To From To From To From To From To From To From To From To From To From To From To06:00- 07:00 35 118 7 19 3 10 11 39 40 30 13 15 21 23 12 18 18 19 3 3 5 3 17 18 500 43 54307:00- 08:00 21 67 10 18 3 22 39 71 66 38 14 20 165 143 17 26 50 59 4 8 8 4 52 51 976 115 109108:00- 09:00 28 101 21 28 9 14 45 88 75 54 23 53 55 74 37 58 49 75 8 10 10 12 51 73 1 1052 147 119909:00- 10:00 47 116 25 29 11 20 50 102 57 22 25 49 47 74 41 64 57 85 10 14 7 4 55 63 1 1075 130 120510:00- 11:00 42 122 30 23 13 13 46 114 45 58 21 55 40 70 45 40 55 107 8 16 5 7 51 55 1081 118 119911:00- 12:00 51 99 27 18 20 20 49 64 37 28 33 46 30 32 49 51 63 66 10 6 6 3 48 53 909 110 101912:00- 13:00 105 99 7 8 18 17 76 48 38 43 48 47 57 46 51 56 82 102 13 8 2 4 43 35 1053 84 113713:00- 14:00 86 88 3 5 17 11 45 41 37 57 28 54 67 52 51 65 80 93 15 12 4 8 43 36 998 91 108914:00- 15:00 63 107 4 4 8 15 72 62 48 60 34 52 61 65 48 57 92 72 10 16 5 5 22 30 1012 62 107415:00- 16:00 90 123 10 8 14 12 58 68 64 65 58 45 84 56 63 50 94 75 15 22 3 1 46 30 1154 80 123416:00- 17:00 138 79 18 21 39 63 43 47 83 48 61 30 69 43 87 64 93 71 16 12 1 3 60 48 1237 112 134917:00- 18:00 76 27 22 8 26 26 25 14 55 38 56 18 67 43 66 27 76 54 28 17 6 5 77 58 915 146 106118:00- 19:00 94 87 19 18 25 48 34 44 64 55 51 38 55 56 66 77 95 104 21 29 7 3 98 84 1272 192 146419:00- 20:00 82 66 14 9 43 54 26 36 56 59 36 42 66 80 65 88 81 64 24 25 6 5 76 61 1164 148 131220:00- 21:00 88 19 11 2 32 22 29 20 32 42 27 23 51 36 56 56 58 26 18 8 2 4 43 29 734 78 81221:00- 22:00 68 49 5 4 34 33 18 64 24 53 25 45 15 19 37 53 27 16 3 5 1 6 21 625 28 65322:00- 23:00 141 83 12 1 65 56 28 36 30 59 33 43 32 25 61 92 46 27 9 4 2 3 23 12 923 40 96323:00- 24:00 66 55 11 1 47 25 12 23 22 30 32 25 26 17 55 71 26 12 3 6 22 18 605 40 64500:00- 01:00 88 57 28 8 9 3 12 31 2 17 13 3 6 22 26 12 2 5 2 346 7 35301:00- 02:00 47 58 15 12 3 4 6 26 1 1 10 14 3 1 11 21 4 2 1 3 4 247 8 25502:00- 03:00 51 63 3 7 7 2 16 13 2 2 11 14 6 1 8 20 6 3 1 3 3 242 6 24803-00 04:00 48 58 7 10 5 3 33 5 6 3 4 12 3 4 2 6 209 8 21704:00- 05:00 38 96 8 9 4 5 52 11 7 8 8 2 6 9 8 10 1 1 3 3 289 7 29605:00- 06:00 50 98 8 4 1 2 36 23 3 15 3 14 21 9 9 12 16 2 2 2 26 16 372 46 418

1643 1935 325 274 456 500 861 1090 876 847 684 755 1042 985 967 1110 1187 1160 218 229 83 77 875 809 1 1

18990 1846 208361723 1439 160 1684 22027 2077 2347 447

Total one way

Total both way 3578 599 956 1951

04.05/06.2009

1 2 3 4 5 6 7 8 9

Heavy TruckTime

10 11 12 13

Large Bus Mini Bus Micro Bus UtilitySmall TruckMedium Truck

G. T

otal

Cycle Rickshaw Cart

Tota

l MT

Tota

l NM

T

Car Auto Rickshaw Motor Cycle Bicycle

Road No.N2

Road NameKatchpur-Tarabo

Location Ref Point (LRP) (km 15.50) Count hours: 48 hrs.

87

Appendix-D: Hourly Traffic Volume Summary Sheet Date:

From To From To From To From To From To From To From To From To From To From To From To From To From To06:00- 07:00 30 72 20 52 3 12 34 34 27 19 10 9 27 30 17 14 15 28 5 3 3 5 20 27 516 55 57107:00- 08:00 27 47 15 19 8 18 37 86 50 33 25 22 110 72 22 21 36 43 8 6 9 6 38 44 802 97 89908:00- 09:00 35 94 11 31 5 15 42 82 88 74 27 68 73 40 37 66 69 77 11 13 7 5 54 38 1062 104 116609:00- 10:00 65 117 13 25 9 14 28 68 70 42 22 43 34 41 52 105 62 68 24 17 10 7 59 60 1055 136 119110:00- 11:00 71 90 7 27 10 13 45 41 77 47 42 26 40 39 53 63 81 84 13 12 2 69 69 1021 140 116111:00- 12:00 73 91 16 23 19 17 59 65 57 47 22 13 46 47 64 79 91 96 13 24 5 3 68 79 1117 155 127212:00- 13:00 97 104 20 27 18 26 47 70 63 45 15 38 46 49 82 89 106 83 11 21 5 7 53 60 1182 125 130713:00- 14:00 85 96 35 31 25 20 53 57 64 47 31 64 40 42 80 90 110 98 20 16 6 3 67 43 1223 119 134214:00- 15:00 80 112 26 28 20 22 50 62 52 44 30 63 35 41 75 106 73 82 5 6 3 8 55 42 1120 108 122815:00- 16:00 72 123 25 25 20 81 37 55 57 27 26 45 25 35 80 95 75 70 7 8 5 7 35 33 1068 80 114816:00- 17:00 69 82 22 22 15 19 38 61 49 25 47 23 40 34 93 47 84 58 13 16 4 1 70 42 1 975 118 109317:00- 18:00 75 88 27 25 25 10 56 59 61 26 62 32 66 65 115 85 112 51 12 9 13 3 45 46 1168 107 127518:00- 19:00 82 103 28 40 21 33 68 82 57 20 70 56 50 58 117 70 102 82 18 12 4 5 55 44 1277 108 138519:00- 20:00 87 57 32 18 15 13 49 45 42 11 47 24 40 40 97 73 87 36 19 9 7 6 50 44 948 107 105520:00- 21:00 110 83 28 20 10 11 37 62 35 30 32 27 45 50 87 59 54 49 12 6 4 3 29 23 906 59 96521:00- 22:00 96 73 35 8 20 9 35 34 29 28 35 31 63 49 60 62 40 15 7 18 1 1 32 781 34 81522:00- 23:00 77 57 28 7 37 9 16 31 25 18 27 21 30 36 20 47 6 14 5 4 10 2 15 14 556 41 59723:00- 24:00 52 72 20 13 25 6 6 18 7 10 17 27 6 16 47 52 13 3 7 2 7 11 437 18 45500:00- 01:00 54 83 22 7 27 9 5 28 5 9 25 13 3 19 23 7 6 5 3 353 8 36101:00- 02:00 34 111 14 6 20 7 13 2 11 5 4 4 6 6 5 248 11 25902:00- 03:00 40 74 15 9 15 9 9 6 2 6 2 7 6 8 5 1 1 1 4 220 4 22403-00 04:00 30 75 8 4 7 4 13 2 1 3 3 8 2 9 2 1 1 2 2 177 4 18104:00- 05:00 31 66 7 5 5 2 29 5 9 1 3 6 8 4 2 3 4 5 3 1 199 9 20805:00- 06:00 26 131 5 11 2 9 12 19 38 5 12 14 12 14 7 6 7 12 1 1 4 14 10 372 28 400

1498 2101 479 483 381 388 805 1085 958 607 618 690 867 821 1245 1265 1235 1067 212 203 99 74 822 778 1 1

18783 1775 20558

G. T

otal

Cycle Rickshaw Cart

Tota

l MT

Tota

l NM

T

Heavy TruckTime Large Bus Mini Bus Micro Bus Utility

10 11 12 13

Small TruckMedium Truck Car Auto Rickshaw Motor Cycle Bicycle

03.04/06.2009

1 2 3 4 5 6 7 8 9

769 1890 1565 1308

Total one way

Total both way 3599 962 173 1600 21688 2510 2302 415

Road No.N2

Road NameKatchpur-Tarabo

Location Ref Point (LRP) (km 15.50) Count hours: 48 hrs.

86

Figure 3.8: Hourly volume of heavy Truck and all other motorized vehicles on one Lane from Katchpur to Tarabo

0

0.2

0.4

0.6

0.8

1

1.2

6 AM-7AM

7 AM -8AM

8 AM-9AM

9AM-10AM

10AM-11AM

11 AM-12AM

12 PM-1PM

1 PM-2PM

2 PM-3PM

3 PM-4PM

4 PM-5PM

5 PM-6PM

6 PM-7PM

7 PM-8PM

8 PM-9PM

9PM-10PM

10PM-11PM

11 PM-12PM

12 AM-1AM

1 AM-2AM

2 AM-3AM

3 AM-4AM

4 AM-5AM

5 AM-6AM

% o

f veh

icle

Time

TRUCKBUSUTILITY/CAR

34

TRUCK BUS UTILITY/CAR6 AM-7AM 53 71 447 AM - 8AM 50 112 132

8 AM-9AM 51 157 1109AM-10AM 87 120 8610AM-11AM 88 164 9311 AM-12AM 108 138 11012 PM-1PM 135 125 128

1 PM-2PM 145 148 120

2 PM-3PM 126 132 110

3 PM-4PM 117 120 105

4 PM-5PM 106 134 133

5 PM-6PM 127 179 181

6 PM-7PM 131 195 167

7 PM-8PM 134 138 137

8 PM-9PM 148 104 1329PM-10PM 152 99 12310PM-11PM 142 68 5011 PM-12PM 107 30 5312 AM-1AM 103 14 32

1 AM-2AM 68 0 5

2 AM-3AM 70 15 15

3 AM-4AM 45 17 17

4 AM-5AM 43 39 10

5 AM-6AM 33 62 19

TRUCK BUS UTILITY/CAR6 AM-7AM 0.282170047 0.3780014 0.234254379 53 71 447 AM - 8AM 0.266198158 0.5962839 0.702763137 50 112 1328 AM-9AM 0.271522121 0.8358622 0.585635947 51 157 1109AM-10AM 0.463184795 0.6388756 0.457860832 87 120 8610AM-11AM 0.468508758 0.87313 0.495128574 88 164 9311 AM-12AM 0.574988021 0.7347069 0.585635947 108 138 11012 PM-1PM 0.718735026 0.6654954 0.681467284 135 125 1281 PM-2PM 0.771974658 0.7879465 0.638875579 145 148 1202 PM-3PM 0.670819358 0.7027631 0.585635947 126 132 1103 PM-4PM 0.62290369 0.6388756 0.559016132 117 120 1054 PM-5PM 0.564340095 0.7134111 0.7080871 106 134 1335 PM-6PM 0.676143321 0.9529894 0.963637332 127 179 1816 PM-7PM 0.697439174 1.0381728 0.889101847 131 195 1677 PM-8PM 0.713411063 0.7347069 0.729382953 134 138 1378 PM-9PM 0.787946547 0.5536922 0.702763137 148 104 1329PM-10PM 0.8092424 0.5270724 0.654847468 152 99 12310PM-11PM 0.756002768 0.3620295 0.266198158 142 68 5011 PM-12PM 0.569664058 0.1597189 0.282170047 107 30 5312 AM-1AM 0.548368205 0.0745355 0.170366821 103 14 321 AM-2AM 0.362029495 0 0.026619816 68 0 52 AM-3AM 0.372677421 0.0798594 0.079859447 70 15 153 AM-4AM 0.239578342 0.0905074 0.090507374 45 17 174 AM-5AM 0.228930416 0.2076346 0.053239632 43 39 105 AM-6AM 0.175690784 0.3300857 0.1011553 33 62 19

0

0.5

1

1.5

2

2.5

3

UTILITY/CAR

BUS

TRUCK

Figure 3.9: Hourly volume of heavy Truck and all other motorized vehicles on one Lane from Katchpur to Tarabo

0

100

200

300

400

500

600

6 AM-7AM

7 AM -8AM

8 AM-9AM

9AM-10AM

10AM-11AM

11 AM-12AM

12 PM-1PM

1 PM-2PM

2 PM-3PM

3 PM-4PM

4 PM-5PM

5 PM-6PM

6 PM-7PM

7 PM-8PM

8 PM-9PM

9PM-10PM

10PM-11PM

11 PM-12PM

12 AM-1AM

1 AM-2AM

2 AM-3AM

3 AM-4AM

4 AM-5AM

5 AM-6AM

Num

ber o

f veh

icle

Time

HEAVY TRUCKSMEDIUM AND SMALL TRUCKSALL VEHICLES EXCEPT TRUCKS

37

HEAVY TRUCKS

MEDIUM AND SMALL TRUCKS

ALL VEHICLES EXCEPT TRUCKS

6 AM-7AM 30 23 135 56 687 AM - 8AM 27 23 288 61 57

8 AM-9AM 35 16 347 62 709AM-10AM 65 22 296 66 5010AM-11AM 71 17 351 115 11711 AM-12AM 73 35 371 112 10212 PM-1PM 97 38 352 12 18

1 PM-2PM 85 60 376

2 PM-3PM 80 46 398 484 482

3 PM-4PM 72 45 320

4 PM-5PM 69 37 307

5 PM-6PM 75 52 484

6 PM-7PM 82 49 482

7 PM-8PM 87 47 381

8 PM-9PM 110 38 3029PM-10PM 97 55 26910PM-11PM 77 65 12911 PM-12PM 62 45 10312 AM-1AM 54 49 53

1 AM-2AM 34 34 5

2 AM-3AM 40 30 32

3 AM-4AM 30 15 35

4 AM-5AM 31 12 52

5 AM-6AM 26 7 89

Figure 3.8: Hourly volume of heavy Truck and all other motorized vehicles on one Lane from Katchpur to Tarabo

0

0.2

0.4

0.6

0.8

1

1.2

6 AM-7AM

7 AM -8AM

8 AM-9AM

9AM-10AM

10AM-11AM

11 AM-12AM

12 PM-1PM

1 PM-2PM

2 PM-3PM

3 PM-4PM

4 PM-5PM

5 PM-6PM

6 PM-7PM

7 PM-8PM

8 PM-9PM

9PM-10PM

10PM-11PM

11 PM-12PM

12 AM-1AM

1 AM-2AM

2 AM-3AM

3 AM-4AM

4 AM-5AM

5 AM-6AM

% o

f veh

icle

Time

TRUCKBUSUTILITY/CAR

34

TRUCK BUS UTILITY/CAR6 AM-7AM 53 71 447 AM - 8AM 50 112 132

8 AM-9AM 51 157 1109AM-10AM 87 120 8610AM-11AM 88 164 9311 AM-12AM 108 138 11012 PM-1PM 135 125 128

1 PM-2PM 145 148 120

2 PM-3PM 126 132 110

3 PM-4PM 117 120 105

4 PM-5PM 106 134 133

5 PM-6PM 127 179 181

6 PM-7PM 131 195 167

7 PM-8PM 134 138 137

8 PM-9PM 148 104 1329PM-10PM 152 99 12310PM-11PM 142 68 5011 PM-12PM 107 30 5312 AM-1AM 103 14 32

1 AM-2AM 68 0 5

2 AM-3AM 70 15 15

3 AM-4AM 45 17 17

4 AM-5AM 43 39 10

5 AM-6AM 33 62 19

TRUCK BUS UTILITY/CAR6 AM-7AM 0.282170047 0.3780014 0.234254379 53 71 447 AM - 8AM 0.266198158 0.5962839 0.702763137 50 112 1328 AM-9AM 0.271522121 0.8358622 0.585635947 51 157 1109AM-10AM 0.463184795 0.6388756 0.457860832 87 120 8610AM-11AM 0.468508758 0.87313 0.495128574 88 164 9311 AM-12AM 0.574988021 0.7347069 0.585635947 108 138 11012 PM-1PM 0.718735026 0.6654954 0.681467284 135 125 1281 PM-2PM 0.771974658 0.7879465 0.638875579 145 148 1202 PM-3PM 0.670819358 0.7027631 0.585635947 126 132 1103 PM-4PM 0.62290369 0.6388756 0.559016132 117 120 1054 PM-5PM 0.564340095 0.7134111 0.7080871 106 134 1335 PM-6PM 0.676143321 0.9529894 0.963637332 127 179 1816 PM-7PM 0.697439174 1.0381728 0.889101847 131 195 1677 PM-8PM 0.713411063 0.7347069 0.729382953 134 138 1378 PM-9PM 0.787946547 0.5536922 0.702763137 148 104 1329PM-10PM 0.8092424 0.5270724 0.654847468 152 99 12310PM-11PM 0.756002768 0.3620295 0.266198158 142 68 5011 PM-12PM 0.569664058 0.1597189 0.282170047 107 30 5312 AM-1AM 0.548368205 0.0745355 0.170366821 103 14 321 AM-2AM 0.362029495 0 0.026619816 68 0 52 AM-3AM 0.372677421 0.0798594 0.079859447 70 15 153 AM-4AM 0.239578342 0.0905074 0.090507374 45 17 174 AM-5AM 0.228930416 0.2076346 0.053239632 43 39 105 AM-6AM 0.175690784 0.3300857 0.1011553 33 62 19

0

0.5

1

1.5

2

2.5

3

UTILITY/CAR

BUS

TRUCK

Figure 3.9: Hourly volume of heavy Truck and all other motorized vehicles on one Lane from Katchpur to Tarabo

0

100

200

300

400

500

600

6 AM-7AM

7 AM -8AM

8 AM-9AM

9AM-10AM

10AM-11AM

11 AM-12AM

12 PM-1PM

1 PM-2PM

2 PM-3PM

3 PM-4PM

4 PM-5PM

5 PM-6PM

6 PM-7PM

7 PM-8PM

8 PM-9PM

9PM-10PM

10PM-11PM

11 PM-12PM

12 AM-1AM

1 AM-2AM

2 AM-3AM

3 AM-4AM

4 AM-5AM

5 AM-6AM

Num

ber o

f veh

icle

Time

HEAVY TRUCKSMEDIUM AND SMALL TRUCKSALL VEHICLES EXCEPT TRUCKS

37

HEAVY TRUCKS

MEDIUM AND SMALL TRUCKS

ALL VEHICLES EXCEPT TRUCKS

6 AM-7AM 30 23 135 56 687 AM - 8AM 27 23 288 61 57

8 AM-9AM 35 16 347 62 709AM-10AM 65 22 296 66 5010AM-11AM 71 17 351 115 11711 AM-12AM 73 35 371 112 10212 PM-1PM 97 38 352 12 18

1 PM-2PM 85 60 376

2 PM-3PM 80 46 398 484 482

3 PM-4PM 72 45 320

4 PM-5PM 69 37 307

5 PM-6PM 75 52 484

6 PM-7PM 82 49 482

7 PM-8PM 87 47 381

8 PM-9PM 110 38 3029PM-10PM 97 55 26910PM-11PM 77 65 12911 PM-12PM 62 45 10312 AM-1AM 54 49 53

1 AM-2AM 34 34 5

2 AM-3AM 40 30 32

3 AM-4AM 30 15 35

4 AM-5AM 31 12 52

5 AM-6AM 26 7 89

Figure-4.7 Showing evaluated deflection values

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

15 16 17 18 19 20 21 22 23 24 25

Chainage (KM)

Def

lect

ion

(mm

)

DBST 25 mmDBST 25 mm

58

Figure 4.4 Road pavement evaluation and rehabilitation procedure (ORN-18 Transport Research Laboratory (UK), Overseas Road Note 18, 1999)

Design and construction data usedto establish lengths of road having a similar type of

construction

Windcreen survey

Trafficsurvey

Roughness survey

Sub-divide and permanently mark road sections or representative lengths

Detail conditionsurvey

Is it a surfacing problem?

Is it localised?

Substructural and materials testing

Identify the causes of pavement deterioration

Select appropriate method of maintenance or rehabilitation

Yes

NoNo

Yes

47

Figure 4.2 Initial deterioration-Longitudinal cracking in asphalt surfacing (ORN-18 Transport Research Laboratory (UK), Overseas Road Note 18, 1999)

ASPHALT SURFACINGLongitudinal cracking

Are the cracks at the centereline

joint or alongside road marking?

NO

YES

Short longitudinal cracks in the wheelpath are often the beginnings of fatigue

cracking (See Figure 8.9). They invariably start at the top of the surfacing as a result

of binder agelng

Are the cracks associated with

transverse cracks?

Are they short cracks in the wheelpath?

Long longitudinal cracks are often the result of subgrade movement. They tend to be associated with a

vertical step across the crack

Initial deterioration is the result of thermal stresses

NO

NOYES

YES

45

Figure 4.3 Initial deterioration-Transverse cracking in asphalt surfacing (ORN-18 Transport Research Laboratory (UK), Overseas Road Note 18, 1999)

ASPHALT SURFACINGTransverse cracking

Is there a chemically stabilshed

roadbase of sub-base?

NO

YES

Initial deterioration is the result of differential movements at structures

such as culverts

Are the cracks associated with

longitudinal cracks?

Are the cracks irregularly spaced

at >20 m spacing?

Initial deterioration is the result of thermal or shrinkage stresses

NO

NOYES

YES

Are they reflection cracks

from a lower pavement layer?

NO

Do the cracks extended the full

width of the road?

Initial deterioration is the result of thermal stresses at

construction joints

NO

YES

Initial deterioration is the result of reflection cracking from

stabilised layer

YES

46