IRC 104:1988 is the Indian Standard (IRC) for guidelines for environmental impact assessment of highway projects. IRC 104:1988 provides the methodology for Environmental Impact Assessment (EIA) and Environmental Management Plan (EMP) preparation for highway and road infrastructure projects in India. It addresses the environmental dimensions — air quality, water, noise, biodiversity, cultural heritage, and socio-economic impacts — that must be evaluated before project approval. EIA scope and requirements are governed by the EIA Notification 2006 and related regulations from Ministry of Environment, Forest and Climate Change (MoEFCC). IRC 104 operationalizes these for highway-sector projects specifically — monitoring locations, methodology, impact prediction tools, mitigation measures. Compliance is mandatory for Category A (> 100 km NH or expressway) and Category B (10-100 km) projects. Public consultation, forest clearance (compensation afforestation 1:1), CRZ clearance (if within 500 m of HTL), and biodiversity protection are key components. Amendment No. 1 (2019) added climate change impact assessment and greenhouse gas emissions tracking; Amendment No. 2 (2023) aligned provisions with the revised EIA Notification and added vehicle electrification considerations for emissions reduction.
Specifies the scope, methodology, and documentation requirements for Environmental Impact Assessment (EIA) and Environmental Management Plan (EMP) for highway and road infrastructure projects in India.
Study area, baseline data periods, monitoring frequency and statutory thresholds for highway EIA.
| Reference | Value | Clause |
|---|---|---|
| EIA — applicable to NH project length above | 100 km (state highway 50 km) — varies by EIA Notification | |
| Study area — corridor of impact | 10 km (each side of alignment) for regional | Cl. 5.2.2 |
| Study area — direct impact zone | 500 m each side of carriageway | Cl. 5.2.2 |
| Baseline data — duration (air, noise, water) | 1 season (3 months) — minimum | Cl. 5.3.1 |
| Baseline data — collection seasons (preferred) | 3 seasons (summer/monsoon/winter) | |
| Air quality — min monitoring stations | 1 per 10 km of project length | |
| Noise monitoring — frequency | Continuous 24-h, both day & night | Annex II (B) |
| Tree felling — compensatory afforestation | 1:1 (minimum); often 1:10 for protected areas | |
| Forest land — diversion approval | Forest Conservation Act 1980 (MoEFCC) | Cl. 3.2 |
| Wildlife corridor — clearance | Required for projects through PA / sanctuaries | Cl. 3.2 / Annex I |
| R&R policy — affected families threshold | Per RFCTLARR Act 2013 | |
| Air quality — CPCB AAQ standard reference | PM2.5 ≤ 40 μg/m³ (annual avg, residential) | |
| Noise — daytime ambient (CPCB) | Residential 55 dB(A); Commercial 65 dB(A) | Table 4.3 |
| Noise — nighttime ambient (CPCB) | Residential 45 dB(A); Commercial 55 dB(A) | Table 4.3 |
| Public hearing — required for | Category A projects (> 50 km NH) |
IRC 104 specifies guidelines for environmental impact assessment of highway projects — the methodology for assessing + mitigating environmental impacts of new highway construction + major upgrades. It complements MoEFCC's broader Environmental Impact Assessment (EIA) Notification framework with highway-specific guidance.
Use IRC 104 when: - Preparing EIA report for new National Highway / State Highway construction - Major widening (4-lane to 6-lane, 2-lane to 4-lane) - Bridge / flyover construction with significant land use - Bypass alignment in environmentally sensitive areas - Tunnel construction - Highway through forest / wetland / hilly terrain - BOT / EPC / HAM project DPR per IRC SP 19:2001
IRC 104 covers environmental aspects: - Land + ecological impact (forest, wetland, biodiversity) - Air quality impact (vehicle emissions, dust) - Noise impact (traffic noise, construction noise) - Water impact (drainage, runoff, water-body crossing) - Soil impact (erosion, cut-fill balance) - Social impact (resettlement, livelihood, public consultation) - Heritage / cultural impact (archaeological sites, monuments) - Climate change considerations (modern revisions)
Regulatory framework: - MoEFCC EIA Notification 2006 + amendments — mandates EIA for major projects - State Pollution Control Boards — clearance for construction phase - Forest Department — for forest land diversion - National Wildlife Board — for sanctuaries / parks - MoRTH guidelines on EIA — IRC 104 provides technical methodology
EIA mandatory for highway projects: - New NH / SH construction > 30 km AND/OR > 50 m wide RoW - Greenfield expressway (any length) - Bypass through eco-sensitive area - Highway through national park / sanctuary / forest > 5 ha - Highway crossing major river / wetland
IRC 104 EIA framework:
1. Project description: - Alignment, length, RoW width - Construction phasing - Material requirements (estimate quarry / borrow needs) - Workforce + housing requirement
2. Baseline environment: - Land use (current use, ownership pattern) - Forest / wildlife (species, habitat) - Air quality (PM, NOx, CO, dust) - Noise levels (background + projected) - Water resources (surface + groundwater; quality + quantity) - Soil + geology (erosion potential) - Climate (temperature, rainfall, monsoon pattern) - Socioeconomic (population, occupation, settlements) - Heritage / cultural (monuments, archaeological)
3. Impact identification + assessment: - Direct impacts (RoW acquisition, construction) - Indirect impacts (induced development, traffic) - Cumulative impacts (combined with other projects) - Magnitude + duration + reversibility per impact
4. Mitigation measures: - Avoidance (alignment changes) - Reduction (technology choices) - Compensation (afforestation, R&R) - Monitoring (post-construction)
5. Environmental management plan (EMP): - Construction-phase: dust + noise + waste + safety management - Operational-phase: traffic management, drainage, vegetation - Cost estimate for environmental measures
6. Public consultation: - Pre-feasibility consultation - Detailed consultation at DPR stage - Public hearing per State Pollution Control Board
7. Monitoring + review: - Pre-construction baseline - Construction-phase monitoring - Post-construction monitoring (3-5 years)
Air quality monitoring during construction: - PM₁₀: ≤ 100 µg/m³ (per CPCB norms) - PM₂.₅: ≤ 60 µg/m³ - NOx: ≤ 80 µg/m³ - CO: ≤ 4 mg/m³ (8-hr avg) - Pre-construction baseline + 3-month construction-phase + 1-year post-construction
Noise levels: - Industrial / construction zone: ≤ 75 dB(A) day; ≤ 70 dB(A) night - Commercial: ≤ 65 / ≤ 55 dB(A) - Residential: ≤ 55 / ≤ 45 dB(A) - Silence zone (hospital, school): ≤ 50 / ≤ 40 dB(A) - Construction noise mitigation: temporary noise barriers, equipment selection (low-noise), restricted hours near sensitive receptors
Forest land diversion: - Compensatory afforestation: 1:1 (non-forest land cost) OR 1:2 if degraded forest - Net Present Value (NPV) compensation: per state forest department rate - Wildlife impact assessment: corridors, crossing structures (animal underpass / overpass)
Water management: - Cross-drainage culverts sized per IRC:5 hydraulic design - Pollution prevention: oil-water separator at fuel storage; dewatering control - Aquifer protection: avoid excessive groundwater pumping
Resettlement + Rehabilitation (R&R): - Per Land Acquisition Act 2013 + state R&R policies - Compensation per market rate - Skill development + livelihood support - Special provisions for SC/ST / vulnerable groups
Greening + landscaping: - Median + roadside plantation - Native species preferred - Maintenance for first 3-5 years post-construction
Cost of environmental measures (typical): - 5-10 % of project cost for EMP implementation - Forest compensation: per state rates - R&R: significant variable; per project specifics
1. EIA prepared after design freeze. Mitigation requires alignment changes; design rework expensive. EIA in parallel with DPR. 2. Inadequate baseline data. Pre-construction monitoring < 1 year; seasonal variation missed. Multi-season baseline. 3. No public consultation or token consultation. Local opposition emerges later; project delays. Genuine consultation essential. 4. Mitigation measures not in EMP cost estimate. Project funding insufficient; EMP not implemented. Realistic cost. 5. Forest land diversion not budgeted. Compensatory afforestation NPV adds 5-15 % to project cost. 6. R&R cost under-estimated. Resettlement land + livelihood support significant; affects financial viability. 7. No wildlife crossing structures on highway through wildlife corridor. Animal-vehicle collisions; wildlife mortality. Provide underpass / overpass. 8. Construction-phase EMP not enforced. Dust, noise, waste mismanaged; complaints + statutory issues. Continuous monitoring + enforcement. 9. No periodic post-construction monitoring. Long-term impact unmonitored; can't validate or improve EMP. Mandatory 3-5 year monitoring. 10. Heritage / archaeological clearance overlooked. ASI (Archaeological Survey of India) can stop work indefinitely. Pre-clearance from ASI for sensitive areas. 11. Climate change / GHG emissions ignored. Modern projects need carbon footprint assessment + mitigation. 12. No alignment alternatives evaluated. Single alignment; no consideration of less-impactful options. Multi-alignment EIA standard practice.
Highway project lifecycle with EIA:
1. Pre-feasibility study (PFS) — high-level alignment + scope. 2. Feasibility study (FS) — detailed; preliminary EIA scope. 3. DPR preparation (IRC SP 19:2001): - Detailed survey + investigation - Environmental Impact Assessment (this code, IRC 104) — full EIA - Geotechnical, hydrological, traffic, design, costs, R&R, compliance documents 4. Statutory clearances: - MoEFCC environmental clearance - Forest clearance (if applicable) - Wildlife / coastal regulation zone clearance - State pollution control board - Heritage / ASI (if applicable) 5. Land acquisition — per Land Acquisition Act 2013 + R&R plan. 6. Tender + award. 7. Construction: - EMP implementation - Continuous monitoring - Post-construction restoration 8. Operations: - Periodic environmental audits - Long-term monitoring (3-5 years post-construction) - Adaptive management based on monitoring results
IRC 104 + the broader EIA Notification framework are increasingly enforced in India. Modern highway projects (Bharatmala, Sagarmala) all have rigorous EIA + EMP requirements; environmental compliance has become a critical success factor.