IRC Codes

No. Unlike many IS codes, IRC codes are sold as priced publications by the Indian Roads Congress. You can purchase print copies or PDFs from the IRC bookshop in New Delhi (Jamnagar House), from authorized distributors, or from the IRC website (ircindia.org). Prices typically range ₹500-₹3,000 per code. Some government organizations (NHAI, MoRTH, state PWDs) provide copies to their staff. InfraLens shows the full scope, title, and key clauses of each IRC code for reference, but not the full text — respecting IRC's copyright.

IRC 6 — Standard Specifications and Code of Practice for Road Bridges, Section II: Loads and Load Combinations governs bridge loading in India. Latest revision IRC 6:2017. It defines: Class 70R loading (70-tonne tracked and wheeled vehicles for national/state highways), Class A (generic commercial traffic — used on most roads), Class AA (heavy tracked/wheeled — defence applications), Class B (rural roads). Also covers dead load, impact, wind, seismic, temperature, shrinkage, creep, footpath live load, and vehicle collision loads on piers.

IRC 21:2000 — Standard Specifications and Code of Practice for Road Bridges, Section III: Cement Concrete (Plain and Reinforced) — is the older working stress based code for RCC bridge design. IRC 112:2020 — Code of Practice for Concrete Road Bridges — is the limit state based replacement, aligned with Eurocode 2. IRC 112 has been the mandated code for new bridge design on NHAI and MoRTH projects since around 2011. IRC 21 may still govern existing bridge assessments and some older projects; for new work, always use IRC 112.

IRC 37:2018 — Guidelines for the Design of Flexible Pavements — is the current code for bitumen-bound asphalt road design. Uses the mechanistic-empirical approach (stress-strain analysis at the pavement-subgrade interface) rather than the older CBR-based empirical method. Design inputs: traffic in million standard axles (MSA), subgrade CBR, climate/rainfall zone, material properties. Outputs: layer thicknesses for bituminous surface, base, subbase, and granular subgrade improvement. Cross-references IRC 81 (Benkelman Beam), IRC 115 (recycled aggregates), and MoRTH specifications.

IRC 58:2015 — Guidelines for the Design of Plain Jointed Rigid Pavements for Highways. Covers PQC (Pavement Quality Concrete) slab design, joint spacing, load transfer devices (dowel bars, tie bars), subbase requirements. For expressways and concrete highways. Uses Westergaard-based stress analysis. Related: IRC 15 (Construction of Cement Concrete Pavements), IRC SP 62 (Continuously Reinforced Concrete Pavement), IRC 68 (Interlocking Concrete Block Pavement).

IRC SP 13 — Guidelines for Design of Small Bridges and Culverts is a practical design guide for culverts, pipe culverts, box culverts, slab bridges, and small span (up to 30 m) structures on rural and lower-volume highways. Widely used on PMGSY (rural roads), state PWD projects, and NHAI site works where a quick design reference is needed rather than the full IRC 112. SP (Special Publications) series tend to be manuals rather than formal codes — they are advisory but widely followed.

IS 1893 (Part 3):2014 — Criteria for Earthquake Resistant Design of Bridges and Retaining Walls — is the primary seismic code for bridges. It replaces the earlier seismic provisions in IRC 6. Covers response spectrum, importance factor, zone factor, and seismic design of bridge substructures. Used with IRC 6 (for loads) and IRC 112 or IRC 21 (for design). For isolated or cable-stayed bridges, additional guidelines from IRC 93 (vibration isolation) and international codes are often referenced.

IRC SP 91:2010 — Guidelines for Road Tunnels — is the primary reference for Indian road tunnels. Covers geometric design, ventilation, lighting, fire safety, drainage, and electrical-mechanical requirements. IRC SP 99 (Expressway road tunnels) extends this for high-speed tunnels. For structural tunnel lining, typical reference is IRC 112 (RCC) or IRC 24 (steel), combined with tunnel-specific references like IS 15026 for monitoring. Rock mechanics for tunnels relies on ISRM guidelines alongside Indian practice.

IRC 78:2014 — Standard Specifications and Code of Practice for Road Bridges, Section VII: Foundations and Substructure — is the code for bridge foundations and substructure design. Covers shallow footings, pile foundations (driven, bored, cast-in-situ), abutments, piers, pile caps, well foundations, wing walls, and approach slabs. Used on every bridge project alongside IRC 6 (loads) and IRC 112 (superstructure).

MoRTH Specifications — *Specifications for Road and Bridge Works* published by the Ministry of Road Transport and Highways — are the official contract specifications for National Highway projects. They reference IRC codes extensively for technical requirements but go further into workmanship, materials, acceptance criteria, and measurement rules. Current version is the 5th Revision (2013) with 2019 amendments. On NHAI and state highway projects, MoRTH specs are contractual; IRC codes are referenced but MoRTH is what binds the contractor. For state roads, state-specific specifications (e.g., MPRDC, PWD) also exist but generally mirror MoRTH.

IRC 75:2015 — Guidelines for the Design of High Embankments — and IRC SP 48 — Hill Road Manual — are the primary references. Hill road design differs significantly from plains: steeper gradients (up to 8% for national highways, 10-12% for lower categories), tighter radii, hairpin bends, cut-and-fill in rock/soil, retaining walls (IRC 102 for RCC, IRC SP 43 for semi-rigid). Combined with IRC 52 (Indian Standards for rural roads in hilly areas), IS 14458 (retaining walls in hill areas), and BRO (Border Roads Organisation) specifications for defence/strategic roads.

IRC codes are revised when underlying technology, practice, or regulations change significantly — typically every 5-15 years. IRC 6 has seen major revisions (1964, 1966, 2000, 2010, 2014, 2017). IRC 112 is relatively new (first published 2011) and has seen amendments since. IRC 37 (flexible pavement) was revised in 2001 and 2018. Smaller Special Publications (IRC SP) get updated less formally. Always verify the current version on the IRC website (ircindia.org) before starting a design — older codes cannot be used on new NHAI/MoRTH projects.