Test: Highway Geometric Design - 3 - Civil Engineering (CE) MCQ

• The lateral friction coefficient is crucial for vehicle stability during turns.
• A design value of 0.15 is typically used for highways, as it accounts for factors like speed and road conditions.
• Higher values like 1.5 or 0.50 are unrealistic; they may lead to unsafe driving conditions.
• A coefficient of 0.15 ensures that vehicles maintain control without excessive sliding or skidding.

If the pavement is kept horizontal across the alignment, the pressure on the outer wheels will be higher due to the centrifugal force acting outwards and hence the reaction RB at the outer wheel would be higher. When the limiting equilibrium condition for overturning occurs the pressure at the inner wheels becomes equal to zero and pressure at outer wheels will be maximum.

Right of way is the area of land acquired for the road, along its alignment. The width of this acquired land is known as land width and it depends on the importance of the road and possible future development.

Factors which govern the alignment of road are,
1. Obligatory points: These are points either the road alignment has to pass or. not have to pass. '
2. Traffic: The new road to be aligned should keep in view the desired lines, traffic flow patterns and future trends.
3. Geometric Design.
4. Economy.
5. Stability of hill-drainage and geometric standard of hili roads.

The camber is given a parabolic elliptic or straight line shape in the cross section parabolic or elliptic shape is given so that the profile is flat at the middle and steeper towards the edges, which is preferred by fast moving vehicles as the have to frequently cross the crown line during overtaking  operation on a two lane highway.

Desigmsffeed on national highway, 
V = 80 km/hr
SSD = vt+ 

The general equation is expressed as y=x²/a, where a=nw/2 for a pavement width of w and cross slope of 1 in n.

The head light sight distance should be at least equal to SSD. If the vehicles are overtaking then length curve should be:

Lag distance = 0. 278 Vt
Reaction time t = 2.5 sec
Lag distance = 55.6 m

2 - 3 - 4 - 1
The step given in 1 is an alternative of step given in 4.

85^th percentile speed is upper limit of speed for regulation and 15^th percentile speed is lower limit of speed for regulation.
The 98^th percentile speed is the design speed,