This standard outlines the code of practice for the design and construction of reinforced and prestressed concrete bridges intended for railway loading. It primarily follows the Working Stress Method, specifying permissible stresses, load considerations like impact and longitudinal forces, and detailing requirements for both superstructure and substructure components.
Provides guidelines for the design and construction of plain and reinforced concrete railway bridges.
Quick Reference Values
Minimum grade of concrete for RCC worksM20
Minimum grade of concrete for PSC worksM35
Permissible direct stress in concrete (σcc) for M205 N/mm²
Permissible bending compressive stress in concrete (σcbc) for M207 N/mm²
Permissible tensile stress in steel (σst) for High Strength Deformed bars230 N/mm²
Maximum clear cover to reinforcement75 mm
Minimum clear cover to main reinforcement in slabs25 mm
Minimum clear cover to main reinforcement in beams40 mm
Key Formulas
Impact Factor (I) = To be calculated as per provisions of IRS Bridge Rules, typically a function of span length. E.g., I = 0.15 + 8 / (6 + L)
Longitudinal Forces = Coefficient * Total load of the train on the bridge (for traction or braking)
Centrifugal Force (C) = (W * V^2) / (127 * R), where W=Live Load, V=Speed, R=Radius of curve
Practical Notes
This code is based on the Working Stress Method (WSM) of design. For modern designs, engineers typically use the Limit State Method (LSM) as detailed in the more current 'IRS Concrete Bridge Code'.
It is essential to use this code in conjunction with the 'IRS Bridge Rules' published by RDSO, which provides the specific live loads (like 25t loading, HM loading) and dynamic impact formulas to be used in design.
While officially reaffirmed, for any new railway bridge project, the latest 'IRS Concrete Bridge Code' is the governing document and should be prioritized over IS 7192.