doto john od1oc2

7/30/2019 Doto John Od1oc2

1/40


2/40

INTRODUCTION

In conflicts of traffic movement at a junction, traffic control

devices facilities can be introduced to minimize the problem.

In Tabata Segerea, Barakuda junction is one of conflict area

.Eventually one of such facilities is necessary. The round-about

will facilitate movements of vehicles through the junction

towards Mandela road which connects Ubungo and Buguruni

area


3/40

PROBLEM STATEMENT

Barakuda junction faces problems like delay of vehicles when

crossing the junction, collision, accidents and traffic congestion.


4/40

PROJECT OBJECTIVES

To design of traffic control devices at Barakuda junction so as to

reduce traffic conflicts and accidents towards Mandela road


5/40

SIGNIFICANCE OF THE PROJECT

The design of traffic control devices it will at the junction

lead proper movements of pedestrian and vehicle


6/40

THE EXPECTED OUTCOME

To provide the design of traffic control devices at Barakuda

junction


7/40

METHODOLOGY

In order to achieve the goal of the project

the following methodology were carried out

Literature review

Data collection

Data analysis

Design


8/40

LITERATURE REVIEW

GENERAL

TRAFFIC CONTROL DEVICESTraffic control devices, These are devices which used to improvethe overall traffic conditions in the most convenient, safe and

economic way .for example, traffic signals permit the vehiclesand pedestrian

To cross in proper manner by controlling conflicts, speedcontrols, control drivers from over speeding.

Junction is the location where two or more roads joins and thetraffic stream cross. It provide a change in direction route wherethe drivers has to decides one of the available choices. It is thepoint of decision at which the numbers of conflicts happens


9/40

REQUIREMENTS OF TRAFFIC CONTROL DEVICES

The installation of these devices should be much that

Draw the attention of the users. Attention depends upon the

location size, colors etc. They should be placed within the cone

of clear vision of road used.Fulfill the need or functional requirement.


10/40

TYPES OF JUNCTIONS

The following are types of junctions as shown below

T-junction

Acute junction

Square junction


11/40

DIAGRAM OF SQUARE-JUNCTION


12/40

COLOURS USED IN TRAFFIC CONTROL DEVICES

Red, used to denote danger or restriction

Blue, indicate information when used on background color on

rectangular signs

Green, used to denote primary roads when used as the

background color on rectangular

Yellow, used exclusively for route number on primary roads

Black and white ,used for symbols and lettering on white and

blue or green background respectively


13/40

THREE TYPES OF SIGNS, GIVING ORDER, WARNING

Regulatory (mandatory),These signs inform the road users

about prevailing laws and regulations for examples no parking

Warning (cautionary)sign, These signs warn the road users

about the existence of certain hazardous conditions. For example

pedestrian crossing

Informatory signs. These signs are for information and guiding

of road users and call attention to thing which might be of

interest to them. For example direction indicators


14/40


15/40

CONTINUOUS OF TYPES OF TRAFFIC CONTROL DEVICES

I Traffic island

Is the type of control device which improve the efficiency of operation at junction, also reduce the area of traffic conflicts

Classification of traffic island

Islands are usually classified according to the purpose for which they are used as listed below 1

Channelizing islands

This used to separate control or direct the movement of traffic streams. They are used to reduce the area , the angle of

conflicts and the speed .These are integral parts of the intersection design. Usual shape is triangular. They may have mountable

or barrier curbs. Large island are used on rural roads than on urban streets.

2 Round about

A central islands of circular , elliptical or other shape located in the Centre of an intersection used for channelization.

3 Divisional island

They used to provide on four or more lane highway to segregate the opposing traffic. They may also be used to separate

through road, service road , or an turning or acceleration lane from the through traffic lane

4 Loading islands

Loading islands are provided at regular bus stops, for protection to bus riders .Railways or fencing may be used for

separation it from adjacent traffic stream. The width depend upon number of bus riders, however, a minimum of 2m wideLoading Island should be used

.

ii. Traffic signals Guide the road users and provide information. Also give warning about abnormal driving ahead


16/40

TYPES OF SIGNALS

I. pre- timed (fixed time )signal

They sequence in which the signals redred, yellow-green-yellow as they appear oneach approach of junctions is fixed and repeated after a fixed interval in second. Theperiod for each signal light is predetermined and fixed in the signals equipment by a

timing device. The cycle length varies from 30sec to 120sec.These signals arecheap and easy to maintain in a progressive type o fixed time signals all fixed timesignals along a route of progressive movement are controlled by a master controllerinstead of individuals timing device at each junction. The change or cycle can bemade from a central control.

ii. Vehicle actuated signalsthese signals change the length of green signal interval, in accordance with the actual

traffic volume on the particular approach of the junction. The vehicle on any junctionapproach are sensed by a detecting device (for example magnetic tape, loop orpneumatic pads), placed in the road. By recording the vehicles as they cross thedetector and by timing the interval between vehicles, the signals are automaticallyadjusted to give preference to the approach with heavier flow


17/40


18/40

TYPES OF TRAFFFIC SIGNAL SYSTEM

i. Coordinated movement

When signals of several consecutive intersections are interconnected andoperated from a single point, the movement of traffic on main road can be bettercoordinated. Timings of consecutives intersection signals are so interrelated that aftercrossing a particular intersection when vehicle approaches the next intersection it

lights by the time also change to green and vehicle does not have to stop for a lengthof road which signals for main road are interrelated

The following are general systems of coordination

ii. Simultaneous system

In this system all the signals along a given route show the same colored lights at thesame time and produces high vehicles speeds between stops but overall speed isrequired.

Iii. Alternative systemThis is when all the signal changes their indication at the same time but

adjacent signals or group of signals on a given road. Show oppose colour.This system works very well on a single that has approximated equal block spacing


19/40

CONTINUATION TYPES OF TRAFFIC SIGNAL SYSTEM

iv Limited progressive system

This system retains a common cycle length butprovides go indication separately at each intersection. This

permits continuous flow of vehicle group at planned speed.v Flexible progressive system,

This is the most efficient of all systems. In this systemlength of cycle, cycle division and the time schedule ateach intersection is varied automatically . Cycle length of

the entire system can be lengthened at peak hours toincrease the capacity and shortened at slack hours todecrease delay.


20/40

WARRANT FOR SIGNALIZED JUNCTION

First warrant; Peak hours minimum volumeThey uses for traffic signals may existing for peak hours oftraffic demands. The warrant for the traffic signals installationunder peak hours volume exceed design peak volume.

Second warrant; number of pedestrian.

The warrant based on the pedestrian total crossing themajor road and major vehicles volume for each of any 8hoursof an average for example

650vehicles/hours approach the junction

150people/hours are crossing the major road.Third warrant; minimum vehicles volume. This criteria is

based when the present volume of junction traffic is theprinciple reasons for consideration of traffic signal installation


21/40

CONTINUATION OF WARRANT FOR JUNCTION

Fourth warrant; crash experience

Based on an accident experienced at the junction warrant is satisfiedwhen the value required to satisfy warrant is met to the eighty percentage.

Fifth warrant ; Continuous flow warrant.

In order for traffic signal to be installed the traffic volume of the major streetand the higher volume of minor street should exceed 900 vehicles/hours inboth approach for major street

100vehicles/hours in one direction for minor street

Sixth warrant; School crossing

School crossing met with the minimum of 20 students crossing in the

highest crossing hour and less than one acceptable gap in the trafficstream per minutes during the highest crossing hour. Engineering judgmentand attention to other remedies (such as crossing guards, improvedsignage, crossing islands) are strongly recommended


22/40


23/40

SIGNALS TERMINOLOGIES

1. Cycle legth

The period required for one complete sequence of signal indication (R-RY-G and Y) is know astime cycle or cycle length .It can vary from 40sec to 120sec depending upon the following

I Volume of traffic on approach

Ii Peak hour volume

The relation between the numbers of vehicle counted during the the highest 15 consecutiveminutes peak hour factor reflect variation in the peaking characteristics of approach and provide

means of evaluating their operation characteriii.Width of the road and junction

iv. Interval

Any one the divisions of the cycle length during which signal indications do not change

V. Inter green duration

The duration between one phase losing right of way and next phase gaining right of way(Termination of green on one phase and the first of green on next phase) followed signal operation isRedRed- Amber-GreenAmber


24/40

CONTINUATION OF SIGNALS TERMINOLIES

According to the British TRRL method or minimum delay methodan approximate formula for determining the optimum cycle length isgiven by the following formula

Co=(1.5+5)/(1-y)seconds

Where by

Co=optimum cycle time (in seconds)L=Total time lost per second (in seconds)

Y=y1+y2+.yn, in which y1,y2 and yn are the maximum ratios offlow to saturation flow for phase 1,2,and .n

The minimum possible cycle time ,which may be associated with

excessively long delays ,is given byCM =L/(1-Y)seconds

Where by

CM =minimum cycle time


25/40

DATA COLLECTION

This is way which involves the collection ofrelated data for specific purposes from differentsources.

Methods of data collections

1 TRAFFI COUNTING.

The traffic counting was done manually todetermine the volume of traffic at the Barakuda

junction for 12hours a day from o600am to 1800pmfor seven day at the intervals of an one hour.

In cities the traffic is connected with officetimings


26/40

METHODS OF TRAFFIC COUNTING

1.Automatic recorders.

The recorders can only determine the number of vehicles not the type of thevehicles and direction of vehicles.

The recorders are of two types

(i)Fixed recorder(ii)Portable recorder

In photo-electric cell method, automatic counter is actuated when light beamfalling on cell is interrupted by the closing the passing vehicle

In electrical methods, the counter is actuated by the closing of electric circuitwhen the car passes.

In the pneumatic method, the counter is actuated by an air switch attached to arubber tube spread across the roadway when the vehicle passes over it

2 Moving car method An observer moving in a car once against the traffic for specific time and record

time along with the traffic recorders the number of vehicles met and overtakenrespectively


27/40

Continuation of traffic counting

Then volume is calculated as follows

V=(X+Y)/(tm+t0)

Where V=vehicle per minutes in one direction

X=number of vehicles when moving against the desired directionin tm minutes

Y=number of vehicles overtaken while moving along with thetraffic in desired direction in to minutes

3. Manual countingEnumerator record the volume of flow on a prepared form areentered according to the types of vehicles.

Pedestrian volume study can be undertaken and shown under othertraffic. This study is necessary to plan signals, pedestrian protectionand installation of barriers and islands and adequate sidewalks.

But he will only concerned with the manual counting method


28/40

Table 1 shows data collection in traffic counting for 7days.

Vehicle typ 6AM- 6AM- 6AM- 6AM- 6AM- 6AM- 6AM- TOTAL

6PM 6PM 6PM 6PM 6PM 6PM 6PM

CARS 7700 7660 7650 7650 7600 7680 4200 50140

PICKUP 1600 1620 1600 1640 1618 1612 1000 10690

L.UNDER 5T 600 601 620 580 595 604 420 4020

L.OVER 5T 480 455 460 500 500 484 220 3099

S.TRAILER 75 72 70 68 74 72 5 436

L.WITH TRAILER 12 10 8 12 8 14 3 67

B.UNDER25S 180 185 180 174 182 188 90 1179

B.OVER25S 240 250 300 246 230 246 150 1662

O.VEHICLE 12 8 12 8 12 6 1 59

TOTAL 10899 10861 10900 10878 10819 10906 6089 71352

[ /


29/40

Table 2 Average traffic volume flow [vehicles/hrs as

shown bellow in the table

Ap. from Mon

30/12

Tue

31/12

Wed

02/01

Thurs

03/01

Frid

04/01

Sat

05/01

Sund

06/01

Mandela 641 637 644 650 648 652 424 4296

T/Segerea 50 51 49 50 47 50 27 324

T/Chango

Mbe

40 42 45 43 41 45 31 287

Vingunguti 10 12 9 11 12 10 5 69

Road

TOTAL 741 742 747 765 748 757 487


30/40

Table 3 Shows the accidents in six years at Barakuda junction.

MONTH 2007 2008 2009 2010 2011 2012

JAN 2 0 1 0 2 0

FEB 1 2 1 1 1 3

MAR 1 1 0 0 0 2

APR 0 2 1 0 1 1

MAY 3 5 2 3 2 0

JUN 2 3 1 2 2 1

JULY 0 2 0 2 1 1

AUG 1 4 1 1 1 0

SEP 0 5 2 1 1 1

OCT 3 2 2 2 0 1

NOV 1 1 2 0 1 3

DEC 0 3 0 2 0 0

TOTAL 14 30 13 14 12 13


31/40

DATA ANALYSIS FOR TRAFFIC COUNTING

Table 4; show the peak hours and normal hours of trafficcounting

Approac

h/Time

0600-

0900

0900-

12OO

1200-

1500

1500-

1800

Total

Mandelaroad

7700 7660 7600 7760 23736

Tabata

Segerea

1600 1620 1600 1635 6455

T|Chang

ombe

460 468 456 482 1866

Vingung

uti

75 80 64 85 304

Total 9835 9828 9720 9962 32361


32/40

Table5;Show average peak hour volume of traffic counting

Approach/Time 0600-0900 0900-1200 1200-1500 1500-1800

Mandela road 654 645 631 678

T/segerera 650 658 61o 670

T/Changombe 414 391 364 458

Vingunguti 480 490 454 586

Total 2198 2184 2059 2392


33/40

Continuation of average peak hours volume of traffic counting

The formula used to calculate the average peak hour volume

was =Total volume of traffic in peak hours/Total hours of

counting.

From the average data shown above. The evening peak hours

especially from {1500-1800} were very high as compared toothers hours. This was because during at that time most of

the people return from their working place toward his /her

homes. Also the traffic volume was changed into average

traffic flows{vehicles/hour} as shown below


34/40

Average traffic volume flows {vehicles/hour}

Approa

ch

from/D

ay

Monda

y

Tuesda

y

Wedne

sday

Thursd

ay

Friday Saturda

y

Sunday Total

Mandel

a

road

641 637 644 650 650 652 424 4298

T/Seger

ea

133 145 150 135 134 140 83 920

Vingun

guti

50 56 52 48 50 50 35 341

T/Chan

gombe

40 38 42 40 42 40 23 265

Total 864 876 888 876 876 882 565 5824


35/40

Chart below show average traffic volume flow

0

100

200

300

400

500

600

700

800

900

days Monday Tuesday Wednesday Thursday Friday Saturday Sunday

Average Traffic Volume Flow

Average Traffic Volume Flow


36/40

Description of the chart above

From the table and chart shown above the flow characteristics at thejunction was very high especially from Monday to Saturday. Thisshows the need of installations of the traffic signal at the junctionwhich will control the traffic flow when crossing the junction.

Traffic volume entering to the main road i.e Mandela road was

652vehicle/hours.

According to the warrant based on minimum the pedestrian totalcrossing to the major road and major vehicles volume for each ofany 8hours of average shown below

{i} 650vehicles/hours approach the junction

{ii}150people/hours were crossing the major road

From the data above there is necessary installation of traffic control device at

the junction.


37/40


38/40

From accidents records charts

From the accident data shown below, the analysis shows that in

six years all the accident were approximately the same

through out from 2007 to 2012. But in 2008 the rate of

accident was very high as compared to the rest of years at

Barakuda junction.


39/40


40/40

REFERENCE

Chandola, S. (1989). Transportation Engineering. Delhi:

Khanna.

R, K. (2003). Traffic Engineering and Transportation Planning

Fourth Edition. Delhi: Khanna.

Vaziran, V. (1988). Transportation Traffic Engineering. Delhi:

Khanna.

doto john od1oc2

Documents