transportation engineering.highway planning,alignment and geometry

Transportation EngineeringUnit-1

Presented By:Ayush Arjaria

HIGHWAY PLANNING, ALIGNMENT & GEOMETRIC DESIGN.

UNIT 1

WHY WE NEED HIGHWAY ?

For “TRANSPORTATION”.

WHAT IS “TRANSPORTATION” ?PROCESS IN WHICH A THING CHANGES IT’S PLACE FROM A

POINT “a” TO A POINT “b”.WHY WE TRANSPORT ? “TO FULLFILL OUR

DEMANDS”

• IN STARTING TRANSPORTATION WAS REMAINED TO WALKING,

• SO JUST A CLEAR,PLAIN PATH ON EARTH WAS ENOUGH FOR TRANSPORTATION NEEDS.

• WITH TIME , DEVELOPMENT TAKE PLACE NEW MODES OF TRANSPORTATION COMES IN EXISTENCE

• LIKE CYCLE , ANIMAL POWERED CARTS.• AS LOAD OF CONVEYANCE INCREASES NEED OF, • STRONGER AND BETTER PATHS TO BARE THAT

INCREASED LOAD.

• THEN REVOLUTION IN TRANSPORTATION COMES • HEAVY WEIGHT MOTOR VEHICLES COMES IN RACE

AND REVOLUTIONALISE MEANING OF TRANSPORTATION.

• BUT , THEY ALSO NEEDS EVEN MORE STONG PATHS THEN BEFORE,HENCE COME IN EXISTENCE PAVED-SURFACED PATHS=ROADS.

AND FROM HERE , COMES NEED OF HIGHWAYS !

AN OVERVIEW

NOW,• After 1st world war motor vehicle using

the road increases and this demanded a better road network.

• Which can carry both animal powered carts and motor vehicles.

• In 1927 a committee was formed to present development of roads in india.

• The committee was “Jayakar Committee”.

NOW,

JAYAKAR COMMITEEo In 1927 jayakar committee for indian road development was

appointed.o Central government should take proper charge of roads considering

it as a matter of national interest.o Emphasis on long term plan of 20 years.o Recommendations for periodic road conferences for discussion on

road development.o Research organisation to be made for research work &

development.o Inclusion of taxation system for transportation.Like, taxation on motor transport,licence fees for vehicles,etc.o The recommendations of jayakar committee gives rise to formation

of I.R.C , C.R.F and C.R.R.I .

Indian Road Congress• Central semi-official body formed

in1934.• For regular exchange of experience &

ideas on matters related to construction and maintenance of highways.

• It provides standardization and recommendations on materials, design of roads and bridges.

On recommendations of jayakar committee government start making 20 year plans for road

developments.There are 4 such plans till date.

Some of salient features of those plans are as

follows…

• Road network classified in 5 categories. NH,SH,M.D.R,O.D.R,V.R .

• Responsibility of making & maintenance of NH assigned to central government.

• Target road length at end of 1961=5,32,700 Km.

• Road density = 16 Km per 100 Km2 by 1963.

• Introduction of star & grid pattern.

20 year Road Plan1st Plan : Nagpur

(1943)

• Road lengths as per nagpur plan was achieved,but road system was deficient in many respects.

• Due to changing economic, industrial,agricultural environment in country, nagpur plan reviewed by government.

• Target road length =10,00,000 Km.• Focus on rural roads. Proposed scientific methods for

making ; more collaboration , exchange of techniques between panchayats and state PWD.

• Road density= 32 Km per 100 Km2.• Entry of express ways. construction of 1600 Km

expressway was also included.

20 year Road Plan2nd Plan : Bombay

(1961)

• Plan prepared by keeping in view the growth and needs by the turn of century.

• Target road length by 1981=12,00,000 Km.• Focus on improving transportation facilities in village,town,etc.• Population over 500 should be connected by A.W.R .• Road density= 82 Km per 100 Km2.• NH network should expanded to form a square grids of 100

Km sides so, that no part of country is more than 50 Km away from NH.

• Expressways should be constructed on major taffic corridors for speedy travel.

• Energy conservation , environmental quality of roads , road safety measures were also included.

20 year Road Plan3rd Plan : Lucknow

(1984)

• Total road length be end of 2021= 5,75,766 Km.• Half of length of NH’s should have 4 to 6 lanes,while rest of half

should have 2 lane carriageway with hard shoulder.• 10,000 Km of SH should have 4 lane ,and 10,000 Km of SH

should have 2 lanes.• 40% M.D.R should have 2 lane carriageway.• Village roads should also have 2 lanes.• Additional sources of funding like toll financing,creation of a

dedicated road fund through additional levies on fuel.• Upgradation of construction technology.• Master plans should be made for rural roads which shows core

connectivity of villages.• All habitations with population above 100 will be connected by

A.W.R.

20 year Road Plan4th Plan : Vision

(2021)

Highway

Weather Carriageway Pavement Surface

Traffic Volume

Tonnage

All weather

Fair weather

Paved

Unpaved

Surfaced Un-surfaced

HeavyLight

Medium Class

1Class 2

Class 3,etc

Classification of Highway

Classification of HighwayModified system

of Highway classificationPrimary

Expressway

National Highway

SecondaryState Highway

Major District Road

TertiaryOther District Road

Village Road

• Road network can be laid in various

patterns. These patterns in which the road network is laid could be

• 1) Rectangular or Block pattern.• 2) Radial or Star and block Pattern.• 3) Radial or Star and Circular Pattern.• 4) Radial or Star and Grid Pattern.• 5) Hexagonal Pattern.• 6) Minimum Travel Pattern.

Road Patterns

Rectangular/Block pattern:

Radial/star block pattern:

Road Patterns

Radial/star grid pattern: Hexagonal pattern:

Road Patterns

Minimum Travel pattern:

Road Patterns

Planning of HighwayWhile planning a highway alignment we should

keep these 4 points in our minds1.safety. It should be safe.2.economy. It should fit in budget

3.Easy. It should easy to make & drive.

4.short. It should cover distance in least possible time.

1. Map Study: In this we study map of area with details . Considering all visible obstructions on map , we draw all possible alignments on map.

Steps in Highway Planning

2. Reconnaissance: In this we study all important historical, geographical features of area from local surveys and other sources.

3. Preliminary: In this we select out the best possible alignment , on basis of economy , ease, covering distance in least possible time.

Steps in Highway Planning

4. Detailed survey: In this we study the selected alignment on ground in reality . giving any further final touch to planning is done here.Key Map: A map which shows the proposed alignment and the existing roads along with connected area.

Factors affecting geometric design of highway:Cross-section. (All the components we see when a road is cut transverse.)

Sight Distance. (Distance we can see in-a-once on road.)

Horizontal Alignment. (Horizontal layout ; left or right turn , change of direction.)

Vertical Alignment. (Vertical layout ; uphill or downhill ; change of grade.)

Intersection. (Where 2 or more paths cross each other.)

Factors affects Highway geometry design

Design control :These are factors which bound our creativity during designing.

1. Design Speed.2. Topography.3. Traffic.4. Hourly Volume.5. Environment.


• Cross-section: It include all features such as: camber , structure, slope, pavement unevenness and friction.

• FRICTION:• On a road , when we move in straight

path then “Longitudinal friction” works on us. It’s value should be between 0.35 to 0.40 .

• When we are on a curve then , lateral friction works on us , it’s value should be 0.15.


• PAVEMENT UNEVENNESS:• It is roughness , unevenness of road.• Measured by “Bump-Integrator” also

called “Roughometer”.• If :• unevenness< 150 cm/Km=Road is good.• 150<unevenness<250 cm/Km=Moderate.• unevenness>350 cm/Km=Repairment

needed.


Bump-Integrator/Roughometer :

• Camber:• The traverse slope formed by

uplifted middle portion of road.• Provided for proper drainage.• Camber is of 3 types:• Parabolic:

(BITUMEN ROAD).• Straight: (CC

ROADS).• Composite:


• SHOULDER:• Also called “Emergency Way”.• Provided on both side of a

carriage way.• Generally shoulders are not

paved.• I.R.C has recommended a

standard width of shoulder as 2.5 m .


• CARRIAGEWAY:• Part of road on which carriage(vehicle) moves.

• Carriageway can be classified in 3 types:• 1) Single Lane = 3.75 m wide.• 2) Double Lane = 7.00 m wide.• 3) Double Lane(with Kerb) = 7.5 m wide.


{ Kerb: The height or depth by which footpath or shoulder lifted up or in depth compare to road level. }

• MEDIANS:• Also known as “Dividers”.• Provided on road to prevent the

head-on collision.• Traffic can be separated, if

divider provided systematically.• I.R.C recommended :• 3 m< width of divider <5 m .


• SUPER-ELEVATION:• It is the upliftment of outer edge of path

with respect to inner edge at curves.• It is provided to counteract the

centrifugal force that act on us at curves.• If not provided , rider will feel jerk , out

controlling of vehicle which can result in an accident.

• Formula:• e + f = v2/(gxR).


{ e= rate of super-elevation in % , f= Lateral friction factor≈0.15 }

• SIGHT DISTANCE:• It is the distance that a road user

can see in-a-once on road.• It is measured from eye level of user.• If proper sight dis. is not provided itmay lead to accidents.


• STOPPING SIGHT DISTANCE:• It is the minimum distance between road

user and obstruction , which is needed to apply brake & get stopped safely , preventing accident.

• “S.S.D=Lag distance + Braking distance” .• Lag Distance: The distance covered between

lapse of time when user saw obstruction and decide to apply brake.

• Braking Distance: The distance covered by vehicle after application of brake.


• STOPPING SIGHT DISTANCE:• Lag distance= (velocity) x

(reaction time) .• Braking distance=

(velocity)2/(2.g.f) .


• Here velocity taken in m/s .S.S.D = L.D + B.DS.S.D = v.TR +

v2 (2.g.f)_____

• HEAD LIGHT SIGHT DISTANCE:• The distance between head light

and the object on the road.

• INTERMEDIATE SIGHT DISTANCE:• It is double of Stopping Sight

Distance.• I.S.D= 2 x S.S.D .


• OVERTAKING SIGHT DISTANCE:• The minimum distance needed

by a fast moving vehicle to overtake a succeeding slow moving vehicle and then come back to it’s lane while keeping safety against opposite traffic coming on other lane.


Overtaking Sight Distance :

• EXTRA WIDENING OF ROADS:• When a vehicle passes a horizontal curve, following things happens:• 1) Direction gets changing continuously and rear wheel doesn’t follow the same path as the front wheel . So, vehicle moves inclinely and hence occupy more distance compare to when it moves on a straight path.



Rear wheels not following path followed by front wheel.

• 2) When a vehicle is on a curve ,a centrifugal force acts on vehicle ,which tends to throw outside of the path. if speed of vehicle is more than the design speed then ,there is full chances that vehicle will go out of path on curve. So ,to prevent the outgoing of vehicle, at curves we provide extra width to road.


• 3) On straight path 2 vehicles can pass by each other with very less distance between them. without any problem.

But,on a curve , human psychology comes in to play.• On a curve users wants as much

distance as much possible, so to get a feeling of safety , while turning on a curve.



Less distance between passing vehicles on straight road.

More distance between passing vehicle on a curve.

( Human Psychology )

• Hence, due to all these factors , a extra widening is provided on curves to prevent any of bad outcomes due to above reasons.

• The total widening of road at curve (We) is finded by taking both mechanical and psychological reasons.

• The mechanical widening of road is due to mechanical reasons. Denoted by “ Wm”.

• The psychological widening of road is due to psychological reasons. Denoted by “ Wp”.


• TOTAL WIDENING OF ROAD:


We = Wm + Wp = nxl2 + v___ ___

(2 x R)(9.5 x √R)We

n= No. of lanes.l= Length of wheel base.R= Radius of curve (m) .V= speed of vehicle (Km/H) .

• It’s a theory to understand concept of “reaction time”.

• The whole process of when a road user interact with a thing on road, can be divided into small time segments.

P.I.E.V THEORY :

P.I.E.V THEORY :

1) Road user see ,the fore coming thing/object

analyse it,eyes capture photo,send to brain brain identify it, figure out it’s harmful or not. The process is “Perception” and time taken in it is “perception time” (Tp).

P.I.E.V THEORY :

2) If the forecoming thing is harmful, brain brain start scanning it’s database,to find ways to act against it ,being safe.Process is intellection and time taken in it is “intellection time” (TI) .

P.I.E.V THEORY :

3) In response to forecoming thing, mind generate related reactive reactions ,with respect to conditions in forms of scream, shock, stunned, cry, jump, etc.Process is “emotion” time taken in it is “emotion time” (Te) .

P.I.E.V THEORY :

4) now, mind had figure out 3-4 ways to counter the harmful interaction, meanwhile the “emotion process”, mind select out and execute most prominent action/way to Prevent/counter harm by interaction.Process is “volition”, time taken in it is “volition time” (Tv) .

P.I.E.V THEORY :

Summation of all the times ( I,e. TP,TI,TE,TV ) is“Total Reaction Time” of an individual.• As, per IRC standard: standard Total Reaction Time for

P.I.E.V THEORY :

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