IRC SP 90:2010 is the Indian Standard (IRC) for guidelines on designing noise abatement measures for urban roads. This guideline focuses on mitigating noise pollution from urban roads. It outlines methodologies for noise mapping, prediction of noise levels, and the evaluation of their impact on sensitive receptors. The code details various noise abatement strategies, including source control (e.g., quieter pavements), path control (e.g., noise barriers), and receiver control (e.g., building insulation). It provides technical specifications and design considerations for each measure, emphasizing their effectiveness and integration into urban planning. The intent is to improve the acoustic environment for urban dwellers affected by road traffic noise.
This IRC code provides comprehensive guidelines for the design of noise abatement measures specifically for urban road networks. It addresses the assessment of traffic noise, the selection of appropriate mitigation strategies, and the design considerations for implementing these measures to reduce noise pollution in urban environments.
Key reference values — verify against the current code edition / project specification.
| Reference | Value | Clause |
|---|---|---|
| Subject | Noise-abatement design for urban roads | Scope |
| Assessment | Predict traffic noise (Leq dB(A)) vs limits | Method |
| Measures | Noise barriers, alignment, surface, planting | Toolbox |
| Barrier design | Height/length from line-of-sight + diffraction | Design |
| Read with | CPCB ambient-noise norms / EIA | Cross-ref |
IRC SP 90 (2010) provides Guidelines on Designing Noise Abatement Measures for Urban Roads — the IRC's standard for traffic-noise control in urban + suburban contexts. With rapid urbanisation + densification, urban traffic noise has become a public-health concern, prompting regulatory + design responses.
Use IRC SP 90 when you are: - Designing urban road / arterial / expressway near residential / sensitive areas - Specifying noise barriers (walls + landscaping) in city projects - Doing noise impact assessment for road project - Working in proximity to hospitals, schools, residential complexes - Doing NHAI / NHAI-City project with noise mitigation requirement - Implementing noise pollution rules + standards
Noise sources from road traffic: 1. Engine noise: mechanical + exhaust 2. Tyre-road noise: rolling contact (dominates at highway speeds) 3. Aerodynamic noise: at high speeds 4. Brake + horn noise: intermittent
Frequency content: - Tyre-road noise: 500-2000 Hz dominant - Engine noise: lower frequencies (50-500 Hz) - Horns + intermittent: broadband
Noise pollution rules (per CPCB): - Industrial area: day 75 dB(A); night 70 dB(A) - Commercial area: day 65 dB(A); night 55 dB(A) - Residential area: day 55 dB(A); night 45 dB(A) - Silence zone (hospital, school): day 50 dB(A); night 40 dB(A) - Daytime: 6 AM to 10 PM; Nighttime: 10 PM to 6 AM
Noise control hierarchy (preferred order):
1. At source (vehicle): - Stricter emission + noise standards - Pavement surface (open-graded asphalt reduces tyre noise 2-5 dB) - Anti-skid road surface design - Regulated horn use
2. Along the path: - Noise barriers (most effective; physical wall) - Landscaping (trees, dense vegetation) - Distance (further from source = less noise)
3. At receiver: - Building insulation - Window glazing - Setback regulations
Noise barrier types:
1. Concrete walls: - Height: 3-7 m typical - Material: pre-cast or cast-in-place concrete - Solid: blocks low-frequency efficiently - Cost-effective for height < 5 m
2. Metal walls (corrugated steel): - Height: 3-5 m - Lightweight; easier installation - Material: galvanized steel + perforated face panel
3. Transparent barriers (acrylic / polycarbonate): - Where view preservation important - More expensive - Limited noise reduction
4. Earth berms: - Natural landscaped earth - Inexpensive but requires space - Combined with vegetation
5. Vegetative barriers: - Dense planted shrubs / trees - Limited acoustic effectiveness (2-3 dB) - Aesthetic + air quality benefit - Long-term to establish
Barrier design: - Height: 1.5-2 m above line-of-sight from source to receiver - Length: extending beyond critical receiver zones - Solid construction: no gaps (each gap reduces effectiveness) - Absorptive lining: sound-absorbing material on traffic side - Tested + certified for acoustic performance
Noise level measurement: - Equivalent sound level (Leq): A-weighted; time-averaged - Daytime: Leq over 16 hours (6 AM-10 PM) - Nighttime: Leq over 8 hours (10 PM-6 AM) - 24-hour Leq: combined day + night with weighting - Maximum sound level (Lmax): peak instantaneous
Distance attenuation: - For point source: -6 dB per doubling of distance - For line source (road): -3 dB per doubling of distance - Atmospheric absorption: additional 0.5-2 dB per 100 m at higher frequencies
Barrier effectiveness: - 3 dB reduction: marginal - 5-10 dB reduction: noticeable improvement - 10-15 dB reduction: significant - 15-20+ dB reduction: very effective (close-source barriers)
Barrier height + geometry: - Line-of-sight breaking is essential (≥ 1.5 m above source-receiver line) - Diffraction over top: typical 5-10 dB reduction - Bottom seal: prevents under-flow; full-height design - Material density: denser material more effective
Barrier length (extending beyond critical zone): - Length-to-distance ratio: 3-4 typical - For wide road, both sides; for narrow road, one side may suffice
Pavement surfacing: - Standard dense graded BC: baseline noise - Open-graded friction course (OGFC): -2 to -5 dB tyre-road noise - Stone Matrix Asphalt (SMA) per IRC:SP-79:2008: -3 to -6 dB - CRMB per IRC:SP-107:2015: -3 to -4 dB
Landscape buffer: - Dense shrubs: 2-4 dB reduction over 30 m - Trees alone: minimal noise reduction; more aesthetic - Combined with earth berm: more effective
Noise impact assessment: - Baseline survey: before construction (1-2 days continuous monitoring) - Predicted future: computer model with project traffic + barrier - Construction-phase: different from operational; temporary - Operational year-1 + year-5 verification
Acceptance criteria: - Barrier acoustic performance per design (laboratory test certificate) - In-situ measurement at receiver to verify achievement - Visual integrity (no gaps, damage) - Long-term durability (corrosion, UV, vandalism resistance)
Special situations: - Hospital / school silence zone: 50/40 dB target; multi-strategy approach - Residential complex: balcony noise often critical; vertical extent of barrier matters - Flyover / elevated road: noise at upper-floor receiver; specific barrier design
Maintenance: - Annual visual inspection - Vegetation maintenance (for earth berm) - Periodic noise verification (every 3-5 years) - Repair / replacement after damage
1. No baseline noise survey. Project proceeds; noise impact unmeasured; later complaints. Mandatory pre-construction noise baseline. 2. Barrier too short. Length insufficient to protect critical receivers; diffraction around ends. Extend beyond critical zone. 3. Gaps in barrier. Single gap can reduce 5-10 dB effectiveness; door / access compromised. Solid barrier; no gaps. 4. Wrong barrier material for environment. Steel in coastal corrodes; concrete in industrial chemical degrades. Material per environment. 5. Foundation inadequate. Wind load + earthquake load on barrier; collapse risk. Per IS 875 + IS 1893 design. 6. No vegetation maintenance. Earth berm + plants; without maintenance, vegetation dies. Maintenance contract. 7. No in-situ verification. Designed performance not measured at receiver. Mandatory verification. 8. Single strategy. Only barrier; no source / receiver actions. Multi-strategy preferred. 9. Surface noise ignored. Bituminous surface dominates highway noise; alternative pavement not considered. Specify noise-reducing pavement. 10. Construction noise ignored. Temporary disturbance during construction not addressed. Construction noise plan. 11. No silencing of horns. Cultural / behavioral; no enforcement. Coordinate with traffic police. 12. No vertical extent for elevated receiver. Upper-floor of building exposed; barrier too short. Vertical barrier extent. 13. Cost-benefit not done. Barrier expensive; alternatives not compared. LCA + benefit analysis. 14. Limited to roads; ignores other sources. Rail, industrial, airport adjacent; cumulative impact. Comprehensive noise study. 15. Vegetation alone for noise reduction. Limited effectiveness; pretty but not solving problem. Combine with physical barrier. 16. Wrong measurement methodology. A-weighted vs C-weighted; daytime vs nighttime; results incomparable. Standard methodology per CPCB. 17. No long-term monitoring. Project gains pass; later complaints uncertain origin. Periodic monitoring.
Noise abatement project — IRC SP 90 touchpoints:
1. Concept + assessment: - Baseline noise survey (pre-project) - Identify critical receivers (hospitals, schools, residences) - Apply regulatory standards - Initial mitigation strategy
2. Detailed design: - Computer modeling (ground level + upper floor receivers) - Barrier sizing + materials - Pavement specification (noise-reducing alternatives) - Landscape integration - Cost-benefit + alternatives analysis
3. Coordination: - With geometric design (IRC:86:1983) - With drainage (IRC:SP-50:2013) - With electrical / lighting - With landscape architecture - With urban planning regulations
4. Detailed drawings: - Barrier elevation + plan - Section through critical receiver - Foundation + structural details - Material specifications + acoustic performance certificate
5. Tender + BOQ: - Barrier materials per type - Foundation works - Pavement (if specified) - Landscape - Acoustic test verification
6. Construction: - Foundation + barrier construction - Connection to existing structures - Pavement (if specified) - Landscape planting - In-situ acoustic test post-construction
7. Quality control + acceptance: - Barrier integrity - Acoustic performance verification - Visual quality - Foundation stability
8. Operations + maintenance: - Annual visual inspection - Vegetation maintenance - Periodic noise re-measurement (3-5 year) - Repair / replacement after damage
IRC SP 90 is the modern urban noise reference for India — applied on Smart City projects, NHAI urban segments, expressway projects through residential zones, and increasingly on metro + suburban arterials.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Daytime Noise Limit (Residential, dBA Leq) | |||
| Nighttime Noise Limit (Residential, dBA Leq) | |||
| Typical Noise Barrier Attenuation (dBA) | |||
| Noise Prediction Model Basis | |||
| Emphasis on Pavement Type |