Guidelines for Environmental Impact Assessment of Highway Projects

IRC 104 – Scope (Clause 4): Key Points

• Scope defines the extent and boundaries of Environmental Impact Assessment (EIA) for highway projects.
• It covers physical and environmental features of all alternatives considered.
• Data should be compiled in a tabular format as per Table 2 (format for alternatives).
• The scope includes assessment of:
  • Land use
  • Soil and geology
  • Water resources
  • Flora and fauna
  • Socio-economic environment
  • Air and noise pollution

Suggested Table Format (Example from Table 2):

Summary:

• Use Table 2 to record comparative environmental features of alternatives.
• The scope ensures comprehensive environmental considerations before project approval.

flowchart TD
    A[Define Project Alternatives] --> B[Identify Physical Features]
    B --> C[Identify Environmental Features]
    C --> D[Record Data in Tabular Format (Table 2)]
    D --> E[Compare Alternatives]
    E --> F[Select Optimal Alternative]

For detailed specs, refer to Clause 4 and Table 2 in IRC 104.

IRC 104: Highway Location – Key Points

1. Highway Location (Clause 2)

• Objective: Select alignment minimizing construction cost, environmental impact, and ensuring safety.
• Consider topography, geology, land use, and socio-economic factors.
• Avoid steep gradients and sharp curves.

2. Highway Alignment (Clause 3)

• Horizontal Alignment: Curves designed for safe speeds; minimum radius depends on design speed.
• Vertical Alignment: Gradients should not exceed limits (typically 4-5% for highways).
• Use crest and sag curves for smooth transitions.

3. Highway Cross-Section (Clause 4)

• Typical cross-section includes:
  • Carriageway width: 7.0 m (two-lane)
  • Shoulders: 1.5 m (paved) + 1.5 m (earthen)
  • Formation width: Sum of carriageway + shoulders + side drains
• Provide camber (2-3%) for drainage.

4. EIA Format for Highway Projects (Clause 5.2)

• Include project description, baseline environmental status, impact assessment, mitigation measures, and monitoring plan.

Sample Formula: Minimum Radius of Curve (IRC Guidelines)

[ R = \frac{V^2}{127 (e + f)} ]

Where:

• (R) = Minimum radius (m)
• (V) = Design speed (km/h)
• (e) = Superelevation (decimal)
• (f) = Coefficient of side friction (typically 0.15)

flowchart LR
    A[Highway Location] --> B[Alignment]
    B --> C[Horizontal Alignment]
    B --> D[Vertical Alignment]
    A --> E[Cross-Section]
    A --> F[EIA Format]

For detailed tables and limits, refer to IRC 104 full text.

Objectives of Environmental Impact Assessment (EIA) as per IRC 104

While IRC 104 does not provide explicit formulas or tables for EIA objectives, the key objectives typically include:

• Identification of Environmental Effects: Assess potential impacts (positive and negative) of road projects on air, water, soil, flora, fauna, and human health.
• Prediction and Evaluation: Quantify the magnitude and significance of impacts using baseline data and modeling.
• Mitigation Measures: Propose practical steps to avoid, minimize, or compensate for adverse effects.
• Decision Support: Provide a scientific basis for project approval, modification, or rejection.
• Public Involvement: Facilitate stakeholder consultation and transparency.

Typical EIA Process (Summary)

flowchart TD
    A[Project Proposal] --> B[Screening]
    B --> C[Scoping]
    C --> D[Baseline Data Collection]
    D --> E[Impact Prediction & Evaluation]
    E --> F[Mitigation Measures]
    F --> G[Reporting]
    G --> H[Review & Decision]
    H --> I[Monitoring & Compliance]

For detailed procedural steps and mitigation related to road projects, refer to IRC 104 clauses 5 and 6.

IRC 104: Highway Cross-Section Key Points

1. Highway Width & Type

• Width depends on design traffic volume (PCU/day), terrain, and road type (single/double lane, two-lane, four-lane).
• Typical lane width: 3.5 m per lane.
• Should include shoulders (1.5-2.5 m), medians (if any), and footpaths.

2. Geometrics

• Curvature: Minimum radius depends on design speed (V, km/h) and superelevation (e), calculated by:
  [ R = \frac{V^2}{127(e + f)} ]
  where (f) = side friction factor (approx. 0.15).

• Gradient: Max gradients vary by terrain and vehicle type; typically:

  • Plain: 4-5%
  • Rolling: 5-6%
  • Mountainous: 7-8%

3. Typical Cross-Section Elements:
   | Element | Width (m) | Remarks | |---------------|-------------------|----------------------------| | Lane | 3.5 | Standard lane width | | Shoulder | 1.5 - 2.5 | Paved or earthen | | Median | 2.0 - 4.0 | For divided highways | | Footpath | 1.0 - 1.5 | In urban or populated areas |

graph LR
A[Roadway] --> B[Lanes (3.5m each)]
A --> C[Shoulders (1.5-2.5m)]
A --> D[Median (2-4m)]
A --> E[Footpath (1-1.5m)]

Summary: Design highway cross-section by accommodating traffic volume, terrain, and safety, ensuring lane widths, shoulders, and curvature follow IRC 104 guidelines.

IRC 104 outlines the Environmental Impact Assessment (EIA) procedure primarily in Sections 5 and 6, focusing on:

Key Steps in EIA Procedure (Section 5)

• Baseline Data Collection: Formats for recording environmental status (air, water, soil, noise, flora/fauna).
• Evaluation of Alternatives: Compare project options based on environmental impacts.
• Impact Assessment: Identify and quantify potential adverse effects.
• Mitigation Measures: Propose actions to minimize negative impacts.

Data Collection & Mitigation (Section 6)

• Systematic approach to gather and analyze environmental data.
• Guidelines for soil erosion control, especially in hilly terrains (Appendices 1 & 2).

Important Tables & Formats

• Baseline Data Recording Formats: For systematic environmental monitoring.
• Checklist for Erosion Control: Ensures sustainable road construction practices.

Summary Table (from IRC 104 Preamble)

Conceptual Flow of EIA Procedure

flowchart TD
    A[Project Proposal] --> B[Baseline Data Collection]
    B --> C[Evaluation of Alternatives]
    C --> D[Impact Assessment]
    D --> E[Mitigation Measures]
    E --> F[Final EIA Report]

For detailed formats and checklists, refer to IRC 104 Sections 5, 6, and Appendices.

IRC 104: Approach to Data Collection & Investigations for EIA Preparation

Key Steps & Specifications:

1. Reconnaissance Survey (Preliminary Stage)

   • Study alternative alignments via maps, photos, field visits.
   • Collect data on terrain, topography, soils, drainage, materials.
   • Prepare plan-profile at 1:50,000 scale.
   • Evaluate alternatives with cost factors.
   • Prepare Reconnaissance Report & draft EIA simultaneously.

2. Preliminary Survey

   • Conduct detailed investigations on selected alignment.
   • Finalize EIA based on updated data.

3. Environmental Impact Factors

   • Consider area type: urban (air/noise pollution), rural (aesthetics), hilly (landslides, erosion).
   • Obtain forest/wildlife clearances if needed.

4. Multi-disciplinary Team

   • Highway/Traffic Engineer, Environmental Specialist, Horticulturist.
   • Add Town Planner for urban roads.
   • Add Geologist/Geotechnical Engineer for hilly terrain.

5. Data Collection for Existing Roads

   • Inventory, terrain, structural condition, land-use, traffic, accident, climatic, wildlife, and pollution data.
   • Use formats in IRC SP:19 and EIA Table 1.

Summary Table: Data Collection Components

Reference:

• IRC SP:19 "Manual for Survey, Investigation and Preparation of Road Projects" for detailed procedures.
• Clause 5.2.6.4 for project acceptability assessment.

flowchart TD
    A[Reconnaissance Survey] --> B[Draft EIA Preparation]
    B --> C[Preliminary Survey]
    C --> D[Final EIA]
    D --> E{Project Acceptable?}
    E -- Yes --> F[Proceed with Project]
    E -- No --> G[Investigate Alternatives]

This approach ensures thorough environmental evaluation and selection of the most sustainable highway alignment.

IRC 104 - Evaluation of Alternatives and Selection of Alignment

Key Points from IRC 104:

• Clause 5.2.4.1: Requires systematic documentation of physical and environmental features of all alignment alternatives.
• Use Table 2 (Proforma) to record data for each alternative, including:
  • Topography
  • Geology
  • Hydrology
  • Environmental impact
  • Social impact
  • Cost estimates

Recommended Procedure:

1. Identify alternatives based on initial surveys.
2. Collect data on physical and environmental parameters.
3. Use a comparative matrix (Table 2 format) to evaluate:
   • Engineering feasibility
   • Environmental sustainability
   • Economic viability
4. Assign weights/scores to each parameter for quantitative comparison (not specified in IRC but a good practice).

Example Table Format:

Tips:

• Prioritize alignments minimizing environmental and social disruption.
• Use GIS and field surveys to gather accurate data.
• Incorporate stakeholder inputs for social impact assessment.

flowchart TD
    A[Identify Alternatives] --> B[Data Collection]
    B --> C[Tabulate Features (Table 2)]
    C --> D[Qualitative & Quantitative Evaluation]
    D --> E[Select Optimal Alignment]

This structured approach ensures a balanced, transparent selection of highway alignment per IRC guidelines.

IRC 104: Mitigating Measures - Summary

IRC 104 does not provide explicit formulas but outlines a structured approach to assess and mitigate environmental impacts of infrastructure projects.

Key Points:

• Data Collection & Investigation:
  Collect detailed environmental data to prepare Environmental Impact Assessment (EIA).

• Impact Assessment Table (Example):

• Overall Assessment (Clause 5.2.6.1):
  • List positive and negative impacts of the selected alternative.
  • Propose remedial measures for negative impacts with expected effectiveness.

Typical Mitigation Measures Include:

• Vegetation preservation or replanting
• Controlled construction practices (dust, noise control)
• Waste management and water runoff control

flowchart LR
    A[Data Collection] --> B[Impact Identification]
    B --> C[Positive Impacts]
    B --> D[Negative Impacts]
    D --> E[Mitigation Measures]
    E --> F[Implementation]
    F --> G[Monitoring & Review]

This approach ensures sustainable infrastructure development minimizing environmental harm.

IRC 104: Construction - Key Points

IRC 104 primarily deals with Environmental Impact Assessment (EIA) for highway projects, focusing on construction phase impacts rather than detailed structural formulas.

Key Specifications for Construction (from IRC 104 & related IRC codes):

• Environmental Features Assessment: Alternatives must be compared on physical & environmental parameters.
• Use Table 2 format (IRC 104, Clause 5.2.4.1) for recording alternatives:

General Construction Guidelines (IRC 104 & IRC 15/6):

• Earthwork: Use standard compaction (Optimum Moisture Content, Maximum Dry Density).
• Pavement Layers: Thickness and material specs per IRC 37/58.
• Drainage: Design as per IRC 6.
• Safety & Environmental Protection: Dust control, noise barriers, waste disposal.

Summary

IRC 104 focuses on environmental assessment and documentation during construction, not structural design formulas. For structural construction formulas, refer to IRC 15 (Earthwork) and IRC 37 (Pavement Design).

flowchart LR
    A[Project Alternatives] --> B[Physical Features]
    A --> C[Environmental Features]
    B & C --> D[Tabular Comparison (Table 2)]
    D --> E[Selection of Best Alternative]

For detailed structural formulas, please specify the construction element (e.g., pavement, bridge).

IRC 104: Air Quality - Key Points & Specifications

1. Air Pollution from Vehicles (Clause 6.2.6)

• Petrol vehicles: CO emission limit during idling ≤ 3% by volume (IS: 9057-1979).
• Diesel vehicles: Smoke density limits:
  • Non-urban: ≤ 70 Hartridge Smoke Units (free acceleration).
  • Full load: ≤ 5.5 Bosch or 80 Hartridge Smoke Units.
• Measurement procedures are standardized but not yet statutory.

2. Assessment Approach

• Divide road into sections with similar features (6.2.3.2).
• Compare existing vs. post-project environmental quality (6.2.3.3).
• Use number of vehicles and volume/capacity (V/C) ratio as air pollution indicators (6.2.6.4).
  • Lower V/C ratio → less congestion → lower pollution.

3. Noise Pollution Limits (IS: 4954-1968)

4. Important BIS Standards for Noise & Emission

• IS 9057-1979: Emission limits for CO in petrol vehicles.
• IS 3028-1980: Noise from moving vehicles.
• IS 4758-1968: Noise from machines.
• IS 9779-1981: Sound level meters.
• IS 10399-1982: Noise from stationary vehicles.
• IS 10423-1982: Personal sound exposure meters.

Summary Diagram: Air Quality Assessment Process

flowchart TD
    A[Divide road into sections] --> B[Collect environmental & traffic data]
    B --> C[Measure vehicle emissions & smoke density]
    C --> D[Calculate V/C ratio and congestion]
    D --> E[Assess ambient air quality impact]
    E --> F[Compare existing vs