IRC Code SP 84: Geometric Design Standards for Four-Lane Highways

India's national and state highways are the arteries of economic growth, supporting millions of vehicles daily. As the country expands its road infrastructure to accommodate growing traffic volumes, geometric design standards become crucial for ensuring safety, efficiency, and sustainability.

One of the most important guidelines for this is the IRC Code SP 84, which lays out the geometric design principles for four-lane divided highways. This blog will walk you through the key provisions of IRC SP 84, its relevance to modern road engineering, and how AI can assist in verifying and implementing these standards efficiently.

What is IRC Code SP 84?

The IRC SP 84 (Indian Roads Congress Special Publication 84) is the authoritative guideline for the geometric design of four-lane highways in India. It covers essential elements such as:

• Carriageway and shoulder width
• Median dimensions
• Sight distances
• Curve design and super-elevation
• Right of way and cross-sectional elements
• Pedestrian and cyclist considerations
• Access control and drainage design

These standards aim to ensure that all four-lane highways are safe, predictable, and uniform, particularly under high-speed traffic conditions on national and state highways.

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Key Geometric Design Provisions in IRC SP 84

1. Design Speed

• For rural areas: 80–100 km/h
• For urban stretches: 50–80 km/h
  Design speed determines curve radii, sight distance, and lane width.

2. Lane Width and Shoulders

• Each lane: 3.5 meters
• Paved shoulder: 1.5 to 2.5 meters
• Earthen shoulder: 1.0 to 2.0 meters

3. Medians and Dividers

• Minimum width: 1.2 meters (raised)
• For future widening or U-turns: up to 5 meters

4. Horizontal Curves and Super Elevation

• Super elevation limited to 7% in plain terrain
• Larger radii required for higher speeds

5. Vertical Curves and Gradients

• IRC SP 84 provides minimum length of vertical curves for smooth transitions
• Gradient capped at 3% for expressways

6. Sight Distance

• Stopping sight distance (SSD) and overtaking sight distance (OSD) are mandatory for design
• SSD for 100 km/h: 180 meters

7. Right of Way (ROW)

• Recommended ROW: 45–60 meters, depending on terrain and future planning

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Why IRC SP 84 Matters for Indian Road Engineers?

• Uniform Standards: Reduces inconsistency in road width, curves, and safety barriers across states
• Safety: Mitigates blind curves, sudden dips, or bottlenecks on highways
• Future-Proofing: Supports future expansion without complete reconstruction
• Contractor Accountability: Makes road audits and inspections more objective

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Challenges in Implementing IRC SP 84

Despite the detailed guidelines, implementation often faces issues:

• Non-engineered deviations during construction
• Lack of real-time compliance checks
• Delayed audits or improper documentation of geometric elements

This is where AI-driven inspection tools come in.

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How RoadVision AI Helps Validate Geometric Design Compliance?

RoadVision AI enables automated validation of roadway design standards using high-resolution imagery and AI-powered analysis.

Here’s how it helps:

1. Curve Geometry Detection

Identifies super-elevation and horizontal curvature using video analytics

2. Lane and Shoulder Width Assessment

Compares actual lane widths with IRC SP 84 requirements

3. Digital Asset Inventory

Maps features like median gaps, signage, crash barriers, and crosswalks

Learn more here:
Road Inventory Inspection

4. Pavement Condition & Geometry Reporting

Combined surface condition and geometric audit helps planners and contractors stay compliant

Explore full capabilities:
Pavement Condition Survey

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Benefits of Using AI with IRC SP 84 Standards

• Real-time design compliance monitoring
• Reduced manual inspection workload
• Improved road safety through proactive validation
• Digital records for audits and public transparency

Whether it’s a government tender or a PPP highway project, using AI ensures that design intent meets execution without compromise.

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‍Conclusion

IRC SP 84 is more than a design guide — it's a foundation for building safe, efficient, and scalable highways across India. As construction expands under national programs like Bharatmala and PM Gati Shakti, adhering to these standards becomes critical.

With smart tools like RoadVision AI, India’s road engineers now have the power to verify compliance, streamline audits, and ensure that four-lane highways meet their design goals from day one.

RoadVision AI is revolutionizing road infrastructure development and maintenance by leveraging cutting-edge AI in road safety and computer vision technology. Through advanced digital twin technology, the platform performs comprehensive road safety audits, enabling early detection of potholes, cracks, and other surface issues, ensuring timely repairs and improved road conditions. It also enhances traffic surveys by providing data-driven insights to address challenges like traffic congestion and optimize road usage. With a focus on building smart roads, RoadVision AI ensures full compliance with IRC Codes, empowering engineers and stakeholders to reduce costs, minimize risks, and improve the overall road safety and transportation experience.

Book a free demo with RoadVision AI today

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FAQs

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Q1. What is IRC SP 84 used for?

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It provides geometric design standards for four-lane highways to ensure safety, consistency, and efficiency in national road projects.

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Q2. Why is super-elevation capped at 7% in plains?

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To avoid vehicle skidding and accommodate safe turning at higher speeds while minimizing construction complexity.

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Q3. Can AI check geometric design compliance automatically?

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Yes, systems like RoadVision AI can verify lane width, curves, and medians using image-based detection and geospatial data.

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