Guidelines for Environmental Impact Assessment of Highway Projects
1988 Edition

Scope Overview (Clause 4):

• Defines the boundaries of Environmental Impact Assessment for highway projects.
• Encompasses physical and ecological characteristics of all considered alternatives.
• Requires data compilation in tabular form following the format of Table 2.
• Covers evaluation of:
  • Land utilization
  • Soil and geological factors
  • Water resource impact
  • Flora and fauna
  • Socio-economic environment
  • Air and noise pollution levels

Example of Suggested Tabular Summary (adapted from Table 2):

Summary:

• Use Table 2 to record comparative environmental data for each alternative.
• Ensures comprehensive consideration of environmental factors prior to project sanction.

flowchart TD
    A[Identify Project Alternatives] --> B[Document Physical Features]
    B --> C[Document Environmental Characteristics]
    C --> D[Tabulate Data (Table 2)]
    D --> E[Analyze Alternatives]
    E --> F[Choose Best Alternative]

Refer to Clause 4 and Table 2 of IRC 104 for full specifications.

Key Guidelines for Highway Location (Clauses 2-4):

1. Highway Location (Clause 2)

• Aim to select routes that reduce construction expenses, environmental harm, and ensure user safety.
• Take into account terrain, geological conditions, existing land use, and socio-economic aspects.
• Avoid steep slopes and sharp bends.

2. Alignment Design (Clause 3)

• Horizontal alignment involves curves designed for safe travel speeds with minimum radii based on design speed.
• Vertical alignment should maintain gradients generally within 4-5%.
• Utilize crest and sag vertical curves for smooth grade transitions.

3. Cross-Section Specifications (Clause 4)

• Standard carriageway width for two-lane roads is 7.0 m.
• Shoulders typically include 1.5 m paved plus 1.5 m earthen shoulders.
• Formation width is the sum of carriageway, shoulders, and side drains.
• Camber of 2-3% recommended for surface drainage.

4. EIA Documentation Format (Clause 5.2)

• Should include project description, baseline environmental conditions, impact evaluation, mitigation plans, and monitoring strategies.

Design Formula: Minimum Curve Radius

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

Where:

• (R): Minimum radius in meters
• (V): Design speed in km/h
• (e): Superelevation rate (decimal)
• (f): Side friction coefficient (usually 0.15)

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

For detailed data and limits, consult the complete IRC 104 document.

Environmental Impact Assessment Objectives as per IRC 104:

Although IRC 104 does not specify formulas or tables for EIA goals, the principal aims generally include:

• Detecting Environmental Impacts: Identify potential positive and negative effects on air, water, soil, biodiversity, and human well-being.
• Forecasting and Assessment: Estimate the scale and significance of impacts using baseline information and predictive models.
• Mitigation Planning: Recommend practical solutions to avoid, reduce, or compensate for adverse impacts.
• Decision-Making Support: Provide scientific evidence to aid approval, adjustment, or rejection of projects.
• Stakeholder Engagement: Encourage public participation and transparency.

Typical EIA Workflow

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

Refer to IRC 104 Clauses 5 and 6 for detailed procedural guidance.

Highlights of Highway Cross-Section Design (IRC 104):

1. Width and Road Type

• Width varies based on traffic volume (PCU/day), terrain conditions, and road classification (single, two-lane, four-lane).
• Standard lane width is 3.5 m.
• Include shoulders (1.5 to 2.5 m), medians where applicable, and footpaths in urban areas.

2. Geometric Parameters

• Minimum curve radius depends on design speed and superelevation, calculated as:

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

  with (f) approximately 0.15.

• Gradient limits vary by terrain:

  • Plains: 4-5%
  • Rolling terrain: 5-6%
  • Mountainous: 7-8%

3. Typical Cross-Section Components:

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

Summary: Cross-section design should reflect traffic demands, terrain, and safety requirements, adhering to IRC 104 guidelines on widths, gradients, and curvature.

The EIA process described in IRC 104 mainly covers Sections 5 and 6 and includes:

Main Steps (Section 5)

• Baseline Environmental Data Collection: Use formatted templates to document air, water, soil, noise, and biological parameters.
• Analysis of Alternatives: Assess different project options focusing on environmental impacts.
• Impact Identification and Quantification: Evaluate the severity and extent of adverse effects.
• Mitigation Planning: Develop strategies to reduce environmental harm.

Data Collection and Mitigation Guidance (Section 6)

• Systematic data gathering and analysis.
• Soil erosion control measures particularly for hilly regions (detailed in Appendices 1 & 2).

Key Tables and Formats

• Templates for baseline environmental monitoring.
• Checklists to ensure effective erosion control.

Summary Table from IRC 104

Conceptual Flowchart

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

For full formats and checklists, see IRC 104 Sections 5, 6, and Appendices.

Approach to Data Acquisition and Investigations for EIA as per IRC 104:

Essential Steps:

1. Reconnaissance Survey (Preliminary Phase)

   • Examine alternative routes using maps, aerial photographs, and field inspections.
   • Gather information on terrain, topography, soil types, drainage, and available construction materials.
   • Prepare plan and profile drawings at a 1:50,000 scale.
   • Evaluate alternatives including cost estimates.
   • Concurrently prepare reconnaissance report and preliminary EIA draft.

2. Preliminary Detailed Survey

   • Conduct in-depth investigations on the preferred alignment.
   • Refine and finalize the EIA report with updated data.

3. Environmental Impact Considerations

   • Tailor focus based on area type: urban (air and noise pollution), rural (visual/aesthetic factors), hilly (landslides, erosion).
   • Secure forestry and wildlife clearances if applicable.

4. Multi-disciplinary Team Composition

   • Core team includes highway/traffic engineers, environmental experts, horticulturists.
   • Add town planners for urban projects.
   • Include geologists and geotechnical engineers for mountainous regions.

5. Data Collection for Existing Roadways

   • Inventory road features, terrain, structural status.
   • Collect land-use data, traffic statistics, accident records, climate, wildlife, and pollution information.
   • Use formats prescribed in IRC SP:19 and EIA Table 1.

Summary Table: Key Data Sources

Reference Materials:

• IRC SP:19 "Manual for Survey, Investigation and Preparation of Road Projects" for comprehensive survey guidelines.
• Clause 5.2.6.4 for evaluating project acceptability.

flowchart TD
    A[Reconnaissance Survey] --> B[Draft EIA Preparation]
    B --> C[Preliminary Survey]
    C --> D[Final EIA Report]
    D --> E{Is Project Acceptable?}
    E -- Yes --> F[Proceed with Implementation]
    E -- No --> G[Explore Alternative Alignments]

This thorough process ensures an environmentally sound selection of highway alignment.

Guidelines for Evaluating Alternatives and Choosing Highway Alignment (IRC 104):

Essential Points (Clause 5.2.4.1):

• Maintain detailed records of physical and environmental attributes of all alignment options.
• Utilize the proforma in Table 2 to document:
  • Topographical features
  • Geological data
  • Hydrological aspects
  • Environmental effects
  • Social impact
  • Cost considerations

Recommended Evaluation Procedure:

1. Identify possible routes based on initial surveys.
2. Gather comprehensive data on each option's physical and environmental traits.
3. Employ a comparative matrix (Table 2 format) to assess:
   • Engineering feasibility
   • Environmental compatibility
   • Financial viability
4. Although not specified in IRC, assigning weights or scores to criteria helps in quantitative decisions.

Sample Comparative Table:

Recommendations:

• Favor alignments that minimize environmental and social disturbances.
• Utilize GIS and field surveys for accurate data collection.
• Incorporate feedback from stakeholders for social impact assessment.

flowchart TD
    A[Identify Route Alternatives] --> B[Gather Data]
    B --> C[Tabulate Features (Table 2)]
    C --> D[Qualitative & Quantitative Assessment]
    D --> E[Select Most Suitable Alignment]

This approach ensures transparent and balanced alignment selection adhering to IRC 104.

Summary of Mitigation Approaches in IRC 104:

While explicit formulas are not provided, IRC 104 outlines a systematic method for evaluating and reducing environmental impacts associated with highway projects.

Highlights:

• Comprehensive Data Collection: Gather detailed environmental information for EIA preparation.

• Impact Assessment Tables: Example format:

• Overall Impact Review (Clause 5.2.6.1):
  • List beneficial and adverse impacts of chosen alternative.
  • Recommend remedial actions for negative effects with expected effectiveness.

Typical Mitigation Measures Include:

• Conservation and replanting of vegetation.
• Controlled construction practices to limit dust and noise.
• Proper management of waste and stormwater runoff.

flowchart LR
    A[Data Collection] --> B[Impact Identification]
    B --> C[Positive Effects]
    B --> D[Negative Effects]
    D --> E[Mitigation Planning]
    E --> F[Implementation]
    F --> G[Monitoring and Follow-up]

This framework helps ensure environmentally sustainable infrastructure development.

Construction Phase Environmental Guidelines in IRC 104:

IRC 104 mainly emphasizes Environmental Impact Assessment during construction, rather than detailed construction structural formulas.

Key Points:

• Compare alternatives based on physical and environmental characteristics using Table 2 format (Clause 5.2.4.1):

General Construction Recommendations (IRC 104, IRC 15, IRC 37):

• Earthwork should follow standard compaction criteria (Optimum Moisture Content, Maximum Dry Density).
• Pavement layer thickness and materials per IRC 37/58.
• Drainage design as per IRC 6.
• Implement dust control, noise barriers, and proper waste management for environmental protection.

Summary

IRC 104 focuses on environmental planning and documentation during construction stages. For structural construction formulas, refer to IRC 15 (Earthwork) and IRC 37 (Pavement Design).

flowchart LR
    A[Project Alternatives] --> B[Physical Characteristics]
    A --> C[Environmental Characteristics]
    B & C --> D[Tabular Comparison (Table 2)]
    D --> E[Select Optimal Alternative]

For structural design specifics, please specify construction components such as pavements or bridges.

Overview of Air Quality and Noise Controls in IRC 104

Vehicle Emission Limits (Clause 6.2.6)

• Petrol vehicles: Carbon monoxide emissions during idling must not exceed 3% by volume (per IS: 9057-1979).
• Diesel vehicles: Smoke density limits:
  • Non-urban areas: up to 70 Hartridge Smoke Units under free acceleration.
  • Full load condition: max 5.5 Bosch or 80 Hartridge Smoke Units.
• Measurement protocols follow standards but are not yet legally mandated.

Assessment Methodology

• Divide the highway into sections with uniform characteristics (Clause 6.2.3.2).
• Compare air quality before and after the project (Clause 6.2.3.3).
• Use vehicle count and Volume/Capacity (V/C) ratio as indicators of pollution levels (Clause 6.2.6.4).
  • Lower V/C ratios indicate less congestion and pollution.

Noise Pollution Limits (IS: 4954-1968)

Relevant BIS Standards for Noise and Emission Control

• IS 9057-1979: CO emission limits for petrol vehicles.
• IS 3028-1980: Noise from moving vehicles.
• IS 4758-1968: Noise generated by machinery.
• IS 9779-1981: Specifications for sound level meters.
• IS 10399-1982: Noise from stationary vehicles.
• IS 10423-1982: Personal sound exposure meters.

Air Quality Assessment Workflow

flowchart TD
    A[Segment Road Sections] --> B[Gather Traffic & Environmental Data]
    B --> C[Measure Emissions & Smoke Density]
    C --> D[Calculate V/C Ratio and Congestion]
    D --> E[Evaluate Ambient Air Quality Impact]
    E --> F[Compare Pre- and Post-Project Conditions]

This structured approach ensures compliance with air and noise quality standards throughout highway development.