Desirable length of Overtaking Zone as per IRC recommendation

The Indian Roads Congress (IRC) is the apex body of highway engineers in India. It has set some guidelines for designing roads and highways. One of the recommendations of IRC is the desirable length of overtaking zone on highways.

Definition of Overtaking Sight Distance

Overtaking sight distance is the minimum distance required for a driver to safely overtake a slower-moving vehicle on a two-lane highway. It is the sum of the distance traveled by the overtaking vehicle during the time the driver takes to perceive the slower vehicle, decide to overtake, and complete the maneuver, and the distance required to bring the overtaking vehicle back into the lane of traffic.

Formula for Overtaking Sight Distance

Overtaking sight distance (OSD) = 0.278Vt + V^2/2g (where Vt is the speed of the overtaking vehicle and g is the acceleration due to gravity)

Desirable Length of Overtaking Zone

According to IRC, the desirable length of overtaking zone on a two-lane highway is five times the overtaking sight distance. This is to ensure that the overtaking maneuver can be completed safely without endangering the lives of the occupants of both vehicles.

Advantages of having a Desirable Length of Overtaking Zone

- It reduces the risk of head-on collisions on two-lane highways.
- It provides enough space for the overtaking vehicle to complete the maneuver safely.
- It gives the driver of the overtaking vehicle enough time to assess the situation and make a decision.
- It improves the overall safety of the highway by reducing the number of accidents caused by unsafe overtaking maneuvers.

Conclusion

The desirable length of overtaking zone on a two-lane highway as per IRC recommendation is five times the overtaking sight distance. This length ensures the safety of both the overtaking and the slower-moving vehicles and reduces the risk of accidents on the highway.