IRC 102:1988 is the Indian Standard (IRC) for traffic studies for planning bypasses around towns. IRC 102:1988 provides methodology for planning bypass roads around congested towns — a common NH/SH intervention in India where trunk routes pass through urban cores. Bypass types: full bypass (entire through-traffic diverted), partial bypass, ring road (encircling urban area), or service road (parallel). Justification requires: through-traffic > 30% of total, peak speed < 40 kmph in town, congestion/safety issues, projected growth > 7%. O-D (origin-destination) surveys at 3-5 stations around town for 3-4 days identify through vs local traffic. Economic evaluation uses Benefit-Cost ratio with benefits from time savings, fuel savings, Vehicle Operating Cost reduction, accident cost reduction, and emissions reduction. Amendment No. 1 (2015) updated with environmental (IRC 104) clearance requirements. Amendment No. 2 (2022) aligned with Bharatmala Pariyojana, a major NH upgrade programme with bypasses as central element. Many Indian NH now have operational bypasses (e.g., Nashik, Aurangabad, Amritsar, Ludhiana, Moradabad, Bareilly) — improving through-traffic speed from 25-35 kmph to 70-90 kmph. Bypass projects typically 20-50 km long, ₹500-2500 crore cost, 4-7 year construction. Proper IRC 102 studies prevent under-design (capacity insufficient) or over-design (economic inefficiency).
Specifies methodology for traffic studies required to justify, plan, and design bypass roads around congested towns/cities on National and State Highways — including O-D surveys, through-traffic estimation, and economic evaluation.
Survey duration, growth rates, design year and economic thresholds for town-bypass justification.
| Reference | Value | Clause |
|---|---|---|
| Bypass — population threshold for study | > 100,000 typically (urban centres) | |
| Origin-Destination (O-D) survey — duration | Continuous 7-day (24×7) at cordon points | |
| Cordon survey — sample size | Min 10% of vehicles intercepted | |
| Through traffic threshold — bypass justification | > 30% of total volume (approx) | |
| Traffic volume count — duration | 7-day classified count | Cl. 4.2.2 |
| Speed-delay study — minimum runs | Min 6 runs (3 each direction) | Cl. 4.4.2 |
| Peak hour factor (PHF) — typical urban | 0.85-0.95 | |
| Annual growth rate — assumed for design | 5-8% (commercial); higher (cars) — adopt project-specific | |
| Design year — bypass facility | 20 years from opening (typical) | |
| Bypass length — geometric efficiency | ≤ 1.5 × straight-line distance ideal | |
| Land-use buffer — bypass setback | 200-500 m clear zone (urban influence) | |
| Junction frequency — bypass main carriageway | ≥ 5 km between major junctions | |
| Travel time saving — bypass justification | ≥ 15 min saved for through traffic | |
| Cost-benefit ratio — economic justification | BCR ≥ 1.0; EIRR ≥ 12% |
IRC 102 (1988) provides Traffic Studies for Planning Bypasses Around Towns — the IRC's methodology for traffic analysis to justify + size bypasses + alternative road routes around congested urban centers. Bypasses are critical infrastructure for relieving city traffic + improving NH/SH continuity.
Use IRC 102 when you are: - Doing traffic study for proposed bypass of city / town - Specifying bypass alignment + sizing - Comparing bypass vs no-action alternative - Doing DPR for NH bypass project - Assessing traffic diversion potential to bypass - Doing multimodal planning with bypass integration
Why bypasses matter: - Relieve city traffic congestion (especially heavy / through trucks) - Reduce vehicle-pedestrian conflicts in city - Improve NH/SH continuity + travel time - Reduce city air + noise pollution (heavy vehicles diverted) - Safety improvement (less mixing of through + local traffic) - Urban development along bypass
IRC 102 covers: - Traffic study methodology (counts, OD survey, classification) - Through traffic identification (potential for bypass diversion) - Bypass routing alternatives - Sizing the bypass (lanes, capacity) - Integration with existing road network - Junction design (entry / exit from bypass) - Economic + traffic-flow analysis - Future-growth provisions
Note: IRC 102 dates from 1988; many concepts remain valid but modern bypass planning supplements with: - IRC:SP-21:2009 (Intersection + Grade Separated Structures) - IRC:SP-64:2017 + IRC:106:1990 (Capacity) - IRC:SP-30:2009 (Economic Evaluation) - IRC:SP-93:2017 (Environmental Clearance) - Current MoRTH + NHAI specifications
Traffic study methodology:
1. Classified vehicle counts: - At entry + exit of city on NH - At intermediate locations on city through-roads - 7-day continuous count typical - Vehicle classification per IRC:3:2021
2. OD (Origin-Destination) survey: - At entry + exit points - Roadside interviews (license plate matching) - Identifies through-traffic (potential bypass users) - Through-traffic % of total: typical 30-60 %
3. License-plate matching: - Recording at entry; matching at exit - Determines travel time + route - Identifies vehicles passing through city
4. Travel-time study: - Through-city travel time (current) - Estimated bypass travel time - Time saved by bypass
5. Through-traffic identification: - Trips originating outside city + destined outside - Diverts to bypass when available - Typical 50-80 % of through-traffic uses bypass when convenient
Bypass design parameters:
Alignment: - External alignment: typically 3-5 km from city center - Connects: main NH approach + exit - Avoid: environmentally sensitive areas, settlements, agricultural prime land - Length: typically 1.5-2× the city through-distance
Cross-section: - NH 4-lane bypass: per IRC:SP-84:2019 - 2-lane + PS bypass: per IRC:SP-73:2015 - Match cross-section to projected bypass traffic
Junctions: - Bypass + city road interchange: typically grade-separated (flyover / interchange) - At-grade intersections at minor city connections - Per IRC:SP-21:2009
Capacity: - Bypass capacity should exceed diverted traffic - Future-proof for 15-20 year horizon - Lane count per traffic forecast
Coordination with city traffic: - Restrict heavy vehicles from city through-roads (mandatory bypass use) - Toll structure (BOT / HAM) — encourage bypass usage - Service road integration for local access - Public transit integration
Service roads + ramps: - Service roads alongside bypass for local access - Ramps at junctions for entry / exit - Service road geometry per IRC:SP-21:2009
Through-traffic %: - Major NH city: 40-60 % of traffic is through - State capital: 30-50 % - District town: 20-40 % - Small town: 60-80 %
Bypass diversion rate: - With toll-free option: 60-80 % of through-traffic - With toll: 40-70 % (depending on value-of-time) - With mandatory restriction in city: 80-95 % - Phased growth: diversion rate increases over years
Bypass capacity: - 2-lane bypass: 8,000-15,000 PCU/day (acceptable) - 2-lane + PS: 12,000-20,000 - 4-lane: 25,000-50,000 - 6-lane: 50,000+
Cost-benefit (typical): - Capital cost: ₹10-50 crore/km depending on cross-section + land - Travel-time savings: 20-40 minutes per through-trip typical - VOC savings: 10-20 % per through-trip - Crash reduction: 30-50 % in city + on bypass - NPV: typically positive for through-traffic > 15,000 PCU/day - IRR: 12-25 % typical (acceptable)
Land acquisition: - Per IRC 102 era: standard land acquisition - Modern projects: per Land Acquisition Act 2013 + R&R - Bypass typically agricultural land: lower than urban land - Compensation per current rates
Environmental clearance: - Per IRC:SP-93:2017 - Often Category A or B per EIA Notification - Forest clearance if any forest land - Wildlife clearance if applicable - Public consultation mandatory
Service life: - Bypass: 25-40 years (with maintenance + traffic growth) - Periodic upgrade as traffic grows - Coordination with city growth
Implementation: - Phased construction if budget constrained - Initial 2-lane + PS: can later expand to 4-lane - Grade-separated junctions: added incrementally - Toll system: can be deployed gradually
Modern bypass practice (vs IRC 102:1988 era): - GIS + traffic modeling tools for alignment optimization - Multimodal planning: integrated with metro / BRT - Smart city integration for digital tolling + traffic management - Environmental sustainability: wildlife corridors, eco-bridges - Future-proofing for autonomous + electric vehicles - PPP / BOT financing dominant for major bypasses
1. Single-year traffic data. Forecast unreliable. 5+ year history if available. 2. OD survey poorly designed. Through-traffic not properly identified. License-plate matching + roadside interviews. 3. Bypass capacity under-sized. Future traffic exceeds; congestion appears. Design for 15-20 year horizon. 4. No restriction enforcement. Through-vehicles continue using city; bypass under-utilized. Coordinate restriction + signage. 5. Alignment through sensitive areas. Environmental issues delay project. Multi-alternative analysis. 6. Land acquisition issues. Compensation disputes; project delayed. Per Land Acquisition Act 2013. 7. Junction design inadequate. Bypass + city road intersections under-designed; congestion. Per IRC:SP-21:2009. 8. No service roads. Local access to bypass severely restricted; community resistance. Service road provision. 9. Tolling structure inappropriate. Toll-free bypass causes city traffic loss; toll discourages use. Cost-benefit analysis. 10. No public consultation. Community opposition emerges late; project delayed. Per IRC:SP-93:2017. 11. No future expansion provision. ROW too narrow for 4-lane expansion. Future-proof. 12. Construction traffic management inadequate. Construction disrupts existing traffic + city. Comprehensive plan. 13. No road safety audit. Per IRC:SP-44:1996. 14. Inadequate environmental clearance. Per IRC:SP-93:2017. 15. No coordination with urban planning. Bypass creates uncontrolled urban sprawl. Planning integration. 16. No multimodal integration. Bypass without bus / metro connectivity. Multimodal planning.
Bypass project — IRC 102 touchpoints:
1. Pre-feasibility: - Traffic problem identification in city - Bypass alternative comparison - High-level cost + benefit - Alignment options
2. Traffic study (per IRC 102): - 7-day classified counts - OD survey at entry / exit - License-plate matching - Through-traffic identification + analysis - Travel-time + speed study
3. Feasibility study: - Bypass routing alternatives - Cross-section sizing - Cost-benefit analysis per IRC:SP-30:2009 - Sensitivity + risk analysis - Recommendation
4. DPR (per IRC:SP-19:2001 + IRC:SP-54:2000): - Detailed alignment + geometric design - Pavement design - Bridge + culvert design - Junctions design - Environmental clearance per IRC:SP-93:2017 - Land acquisition planning
5. Tender + award: - Per NHAI EPC / HAM / BOT contracts - Quality + maintenance specifications
6. Construction: - Land acquisition completion - Construction per design + IRC codes - Quality control per IRC:SP-47:2018 + IRC:SP-57:2015
7. Pre-opening: - Road safety audit - Signage + tolling system - Restriction enforcement
8. Operations + maintenance: - Traffic monitoring (verify diversion %) - Periodic upgrades - 25-40 year service life
IRC 102 is the bypass-planning reference in India — applied on hundreds of NH/SH bypass projects nationwide, providing relief to congested city centers + improving inter-city travel.