IRC 71:1977 is the Indian Standard (IRC) for recommended practice for road signs on national highways and other roads. IRC 71:1977 is the foundational Indian recommended practice for road signs on highways and other roads. It defines sign classification (Mandatory circular red-white, Warning triangular yellow-black, Informatory rectangular blue-white/green-white), dimensions (600-900 mm standard), colour convention, lettering, retro-reflective sheeting (Engineer Grade for urban, High-Intensity Prismatic for NH, Diamond Grade for expressways), installation height, advance placement, and spacing. It aligns with UN Convention on Road Signs and Signals (1968) for international consistency. Though 1977 is old, IRC 71 remains fundamental — modern updates come via IRC 67:2022 (newer sign types), IRC 35 (road markings), IRC 106 (signs for motorways). Every NH project signage contract references IRC 71 for design standards. Compliance is verified at commissioning by NHAI / state PWD.
Specifies the type, colour, dimensions, lettering, symbol design, and installation of road signs on National Highways, State Highways, and other roads across India, in conformity with UN Convention on Road Signs and Signals.
Sign sizes, mounting heights, advance distances and retroreflective sheeting classes for NH signs.
| Reference | Value | Clause |
|---|---|---|
| Sign post mounting height — bottom of sign above ground | 1.5 m (rural); 2.0 m (urban with footpath) | |
| Mandatory sign — circular plate diameter (NH) | 900 mm (highway); 600 mm (urban) | Table 6.1 |
| STOP sign — octagonal across-flats | 900 mm (NH); 600 mm (urban) | Table 6.1 |
| GIVE WAY sign — equilateral triangle side | 900 mm (downward apex) | Table 6.1 |
| Cautionary sign — equilateral triangle side | 900 mm (NH/SH); 600 mm (urban) | Cl. 7.3 |
| Cautionary sign — apex orientation | Apex upward | Cl. 7.2 |
| Informatory sign — rectangular (typical size) | 750 × 600 mm (small) to 2400 × 1200 mm (gantry) | |
| Direction sign — chevron board | 300 × 900 mm typical | |
| Lateral clearance — sign edge from carriageway | 0.6-2.0 m (varies with speed) | |
| Cautionary sign — distance ahead of hazard (V=100) | 150-200 m | |
| Cautionary sign — distance ahead of hazard (V=50) | 50-100 m | |
| Sign letter height — V=100 km/h (overhead) | 200-300 mm | |
| Sign letter height — V=50 km/h (post-mount) | 100-150 mm | |
| Retroreflective sheeting — NH highways | Type IV (high-intensity prismatic) min | |
| Retroreflective sheeting — expressways | Type IX / XI (diamond grade) preferred | |
| Sign substrate — aluminium thickness | 1.5 mm (small) – 2.0 mm (large) | |
| Cantilever / gantry — vertical clearance | 5.5 m (under sign edge) | Cl. 2.6.3 |
IRC 71:1977 is the recommended practice for road signs on national highways and other roads — the foundational Indian standard for highway and road signage that defines sign types (regulatory, warning, informatory), shapes, colours, sizes, lettering, and placement. It was the workhorse signage code for over 40 years.
Important context: Largely superseded by IRC:67:2012, which consolidates and updates road sign practice for modern Indian conditions (more vehicle types, more international alignment, more sign categories). For new contracts, always reference IRC:67:2012, not IRC 71:1977.
Use IRC 71 as a reference when: - Working on legacy NHAI / state highway projects with old contract references - Reverse-engineering existing roadside signage installed in the IRC 71 era - Heritage / archive work on Indian road infrastructure documentation - Cross-referencing older accident investigation reports that cite IRC 71 - Field engineers reading older drawings
For any new design / construction, use IRC:67:2012 which is the current authority.
IRC 71 was the first comprehensive signage code in India; its principles (sign categorisation, retroreflective requirements, placement rules) carried into IRC:67:2012 with refinements based on 35 years of field experience.
Three categories of road signs:
1. Regulatory signs (mandatory action): - Stop, Give Way, No Entry, Speed Limit, No Parking, Direction-only - Shape: usually circular or octagonal (Stop) - Colours: red border on white background (most), red circle with diagonal slash (prohibitive), blue background with white symbol (mandatory action) - Driver must obey under traffic law
2. Warning signs (cautionary): - Curve ahead, Cross-road, Speed breaker, Slippery road, Pedestrian crossing, Animals, School ahead, Falling rocks, Steep gradient - Shape: equilateral triangle (apex up) - Colours: red border on white/yellow background, black symbol - Advance distance: typically 50-150 m before hazard depending on highway speed
3. Informatory signs (information): - Direction signs (place names, distances), road name, hospital, parking, fuel station, food / lodging - Shape: rectangular - Colours: green / blue background with white symbol/text (typical for direction signs); black on white for facility info
Sign sizes (typical for highway speeds): - 40-60 km/h: 600 mm circle / triangle / square base - 60-80 km/h: 750 mm - 80-100 km/h: 900 mm - > 100 km/h: 1200 mm
Lettering: - Capital letters; height proportional to viewing distance - 100 km/h highway: lettering 200 mm tall; visible at ~150 m - 80 km/h highway: 150 mm; visible at ~100 m
Mounting: - Single-post or twin-post galvanised steel pole - Mounting height: 2.0-2.5 m clear above pavement edge (rural); 2.0 m (urban) - Lateral offset: 1.5-3.0 m from pavement edge (per IRC:73 cross-section) - Retroreflective sheeting (Class B minimum, Class A or HIP for highway)
What changed from IRC 71:1977 to IRC:67:2012:
Practical implication: - New contract drawings must cite IRC:67:2012, not IRC 71:1977 - Field installations made under IRC 71 are still valid; replacement during periodic maintenance should upgrade to IRC:67:2012 standards - Manufacturers now produce signs to IRC:67:2012; IRC 71 dimensions are obsolete for procurement - Sign-language / pictograms standardised by IRC:67:2012 (uniformity across India)
Current authoritative code: - IRC:67:2012 — code of practice for road signs (the current standard).
Related current codes: - IRC:35:2015 — code of practice for road markings. - IRC:99:2018 — vehicular barriers (signage on barriers). - IRC SP 41:2005 — at-grade intersections. - IRC SP 23:2012 — vertical curves (warning signs at sight-distance restrictions). - IRC SP 55:2014 — safety in road construction zones (work-zone signage). - IRC SP 88:2019 — speed breakers (advance signage). - IRC:5:2015 — bridge design (clearance signage). - IRC:73:1980 — geometric design standards (sign placement geometry). - IRC:103:2012 — pedestrian facilities (pedestrian-specific signage). - MoRTH Specifications for Road and Bridge Works (5th Revision) — material and construction specs for signs. - ISO 7010 / Vienna Convention on Road Signs and Signals — international references for symbol-based signs.
1. Citing IRC 71:1977 in new contract. Should be IRC:67:2012; legacy citation indicates outdated specification. 2. Old sign sizes for high-speed highway. IRC 71's largest sign was 900 mm; modern NHAI / expressway needs 1200 mm or larger for visibility at 120 km/h. Use IRC:67:2012 tables. 3. Class B sheeting on national highway. Modern NHAI specifies Class A (high-intensity) or Class IV (HIP — high-intensity prismatic) for permanent NH signs. Class B is for state / district roads and temporary signage. 4. Lettering height inadequate for design speed. Letters must be readable at viewing distance × 1 second response. Use IRC:67:2012 lettering tables for current best practice. 5. No vandalism / corrosion protection. Galvanised pole + powder-coated face standard; cheaper installations rust within 2-3 monsoons. 6. Sign placement obstructs sight triangle. Sign at intersection corner blocks driver's view of approaching traffic. Place outside sight triangles per IRC:66:1976. 7. Sign too low (mounting height < 2 m). Tall trucks contact, damage. Maintain 2.0-2.5 m clear above pavement edge. 8. No regular cleaning / replacement. Faded retroreflective sheeting loses effectiveness; signs become invisible at night. Annual cleaning, periodic replacement (5-7 year cycle for HIP sheeting). 9. Bilingual signage arbitrary. Local language + Hindi + English on the same sign with consistent hierarchy per IRC:67:2012; not random. 10. Sign dimensions not visible to small drivers / motorbikes. India's most common vehicle is two-wheeler with low eye height. Place signs at heights and sizes suitable for both car and two-wheeler driver eye levels.
Sign + marking design cascade for a new road project:
1. Geometric design (IRC:73, IRC:38, IRC SP 23) — establishes road geometry that signs will guide. 2. Hazard identification — sharp curves, intersections, pedestrian zones, sight restrictions; map all advance-warning sign locations. 3. Information needs — distance signs, direction signs, place names, facility signs. 4. Sign type selection (IRC:67:2012) — regulatory / warning / informatory. 5. Sign size + sheeting class — per highway speed and importance. 6. Placement — advance distances, mounting height, lateral offset. 7. Coordination with markings (IRC:35:2015) — signage + marking as system. 8. Construction and installation — galvanised post, mounting hardware, retroreflective face. 9. Operations + maintenance: - Routine cleaning (monthly in dusty zones) - Periodic inspection for damage / theft / fade - Replacement at end of life (5-7 years for HIP; 3-5 for Class B) 10. Audit — periodic safety audit reviews signage adequacy; weather / traffic / accident conditions may demand changes.
IRC 71 was the foundation; IRC:67:2012 is the current building. Practitioners working on new projects should default to IRC:67:2012; IRC 71 serves as historical reference only.