Design speed and Sight distance at intersection

Design speed of a road is the maximum safe speed that can be maintained by a vehicle under ideal conditions of alignment, grade, and traffic control. Sight distance, on the other hand, is the distance that a driver can see ahead of their vehicle while driving. It is an important factor in determining the safety of a road, especially at intersections.

Relationship between design speed and sight distance

The sight distance required at an intersection depends on the design speed of the road. The higher the design speed, the greater the sight distance required, as vehicles will be traveling faster and will need more time to react to obstacles or hazards.

Calculation of sight distance at intersection

The formula used to calculate sight distance at an intersection is as follows:

Sight distance = Stopping sight distance + Passing sight distance

Stopping sight distance is the distance required for a driver to stop their vehicle, given a certain speed and a certain coefficient of friction between the tires and the road surface. Passing sight distance is the distance required for a driver to safely pass another vehicle.

For a design speed of 100 kmph, the minimum sight distance required at an intersection is 220 meters. This takes into account both stopping and passing sight distance.

Importance of adequate sight distance at intersections

Having adequate sight distance at intersections is crucial for ensuring the safety of drivers, passengers, and pedestrians. Without enough sight distance, drivers may not be able to react in time to avoid a collision or other hazard. This can lead to serious accidents and injuries.

Conclusion

Design speed and sight distance are important factors to consider when designing a road, especially at intersections. Having adequate sight distance is crucial for ensuring the safety of all road users. For a design speed of 100 kmph, the minimum sight distance required at an intersection is 220 meters.