Loadings of bridges have been standardized by the Roads Congress. The major features of the various load classes are given below :
Bridges and culverts on National Highways are designed for one lane of Class 70 R or two lanes of Class A loading, whichever produces more severe stresses.
IRC Class AA loading is to be adopted within certain municipal limits, in certain contemplated or existing industrial areas, in other specified areas, or a long specified highways.
RC Class A load is to be normally adopted on all roads on which permanent bridges and culverts are constructed.
IRC Class B loading is to be normally adopted for temporary structures (for example timber structures) and for bridges in specified areas.