In class B train of vehicles loading, the nose to tail distance between successive trains

Concept:

IRC Class A Loading:

• The Indian Roads Congress (IRC) is the Apex Body of Highway Engineers in the country. The IRC was set up in December 1934 on the recommendations of the Indian Road Development Committee best known as Jayakar Committee set up by the Govt. of India with the objective of Road Development in India.
• The Class A loading was proposed by IRC with the objective of covering the worst combination of axle spacing and axle loads likely to arise from the various types of vehicles that are normally expected to use the road.
• The loading consists of a train of wheel loads that is composed of a driving vehicle and two trailers of specified axle spacings and loads. This loading in bridge designing is generally adopted on all roads on which permanent bridges and culverts are constructed.

Explanation:

• The nose-to-tail distance between successive trains shall not be less than 18.5m.
• No other live load shall cover any part of the carriageway when a train of the vehicle (or trains of the vehicle in multilane Bridge) is crossing the bridge.
• The minimum clearance ‘f’ between the outer edge of the wheel and the roadway face of the kerb, and the minimum clearance ‘g’, between the outer edge of passing or crossing vehicles on a multi-lane bridge, shall be as given below. 

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