This presentation deals with all the major steps involved in the survey, selection of the most possible route and the designing of the highway.
It will brief u on all the major topics of highway designing
• It is needed since every commodity produced
whether it is food, clothing, industrial products or
medicine needs transport at all stages from
production to distribution.
• Road transport is requires relatively less investment
from government hence is used most widely and is
most efficient mode of transport.
First 20 yr
• Also known as Nagpur Road Plan (1943-1963).
• Road density 16 km/100 sq. km.
Second 20 yr
• Also known as Bombay Road Plan (1961-1981)
• Road Density 32 km/100 sq. km.
Third 20 yr
• Also known as Lucknow Road Plan (1981-2001)
• Road Density 82 km/100 sq. km.
1. Jayakar Committee.
2. Central Road Fund.
3. Indian Road Congress.
4. Motor Vehicle Act.
5. Central Road Research Institute.
6. National Highway Act
CLASSIFICATION OF ROADS
• National Highway
• State Highway
• Major District Road
• Other District Road
• Village Road
• Primary System
• Secondary System
• Tertiary System
• To arrive at the road net-work out of several alternate possible
road systems .
• To fix up priority of the construction projects .
• To assess the actual road use by studying the traffic flow patterns .
• Designing using previous data and past experience of traffic type,
intensity, performance of existing roads etc.
• Comparison of areas for information on areas for immediate need
for road network .
• The data obtained in fact finding surveys may be analysed for the
future trends in development of an area . This information is
useful in the future planning .
1. It is the actual distance along the road surface,which a driver
has visibility of stationary or moving objects.
2. Restrictions to this may caused at horizontal curves, vertical
curves or at intersections.
• Often changes in the direction are necessitated in highway
alignment due to obligatory points.
• Alignment should enable consistent, safe and smooth
movement of vehicles operating at design speeds.
• Horizontal Alignment Consists:-
– Design Speed
– Horizontal Curves
– Super elevation
– Widening of Pavement
– Transition Curve
• Main factor on which Geometric design elements depends
• Design Speed depends on
– Class of the Road
Design Speed in Kmph for Various Terrain
Plain Rolling Mountainous Steep
Ruling Min Ruling Min Ruling Min Ruling Min
NH & SH 100 80 80 65 50 40 40 30
MDR 80 65 65 50 40 30 30 20
ODR 65 50 50 40 30 25 25 20
VR 50 40 40 35 25 20 25 20
• It is a curve in plan to provide change in direction to the center
line of road.
• The centrifugal force develops depend on the radius and the
speed of the vehicle negotiating the curve.
• Centrifugal force has two effects
– Tendency to skid the vehicle.
• Transverse inclination to the pavement surface
• To counteract the effect of Centrifugal force.
• Objectives of extra widening.
– To prevent Off Tracking
• Types of extra widening.
– Mechanical Widening
– Psychological widening
• Curve having radius decreasing from infinity at tangent to
– Gradually introduce centrifugal force
– Turn steering gradually
– To gradually introduce Super elevation & Extra Widening
• The vertical alignment is the elevation or profile of the centre
line of the road.
• It consists
– Vertical Curves
• Rate of rise or fall along the length of road w.r.t. the horizontal.
• Expressed as ratio of 1 in x (1 vertical in x horizontal)
– Ruling gradient
– Exceptional gradient
– Minimum gradient
• These are introduced to smoothen out the vertical profile
• Types of vertical curves
– Summit curve with convexity upward
– Valley curve with concavity upward