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RoadvisionAI enhances Road Safety Engineering by enabling AI road marking inspection, helping authorities maintain Longitudinal Road Markings in compliance with Pavement Marking Standards defined under IRC:35-2015.

Road safety begins with clear communication. On highways and city streets, road markings act as a silent language guiding drivers every second. Among them, Longitudinal Road Markings form the backbone of lane discipline, overtaking control, and safe vehicle guidance.

Standardised by the Indian Roads Congress under IRC:35-2015, these markings ensure uniformity across India’s expanding road network from rural highways to high-speed expressways.

As the saying goes, “Small things make a big difference.” In traffic engineering, that difference saves lives.

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1. What is IRC:35-2015?

IRC:35-2015 – Code of Practice for Road Markings provides structured guidance for:

• Road marking design and layout
• Material selection
• Placement rules across road categories
• Retroreflectivity requirements
• Maintenance and compliance standards

Its purpose is simple: ensure clarity, consistency, and nationwide safety.

When it comes to traffic control, clarity is not optional it is essential.

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2. What Are Longitudinal Road Markings?

Longitudinal Road Markings are pavement lines laid parallel to the direction of traffic flow.

As defined in IRC:35-2015, they help to:

• Guide vehicles within lanes
• Separate opposing traffic streams
• Regulate overtaking
• Improve safety at curves and intersections
• Enhance visibility during night or adverse weather

They are foundational elements of Road Safety Engineering and organised traffic movement.

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3. Classification of Longitudinal Markings (As per IRC:35)

IRC categorises longitudinal markings under the LM series based on function and geometry.

3.1. Broken Lines (LM01, LM02)

Purpose: Lane separation where overtaking is permitted

Application:

• Standard highway stretches
• Multi-lane roads

Broken lines indicate that crossing is allowed when safe.

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3.2. Single Continuous Lines (LM21, LM22)

Purpose: Prohibit lane changing or overtaking

Used At:

• Sharp curves
• Narrow bridges
• Intersection approaches

These lines clearly communicate that overtaking is unsafe.

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3.3. Double Continuous Lines (LM23, LM24)

Purpose: Strict no-overtaking control

Common Locations:

• Hill roads
• Blind bends
• High-risk junctions

In such zones, safety overrides speed.

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3.4. Combination Lines (LM28, LM29)

Design: One continuous line combined with one broken line

Function:

• Overtaking allowed in one direction
• Prohibited in the opposite direction

This design ensures directional flexibility while maintaining controlled traffic behaviour.

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3.5. Warning Lines (LM04, LM05)

Design: Broken lines with shorter gaps

Indicates Approach To:

• No-overtaking zones
• Sharp curves
• Hazardous alignments

Warning lines prepare drivers for changing road conditions in advance.

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4. Why Longitudinal Road Markings Matter

Longitudinal Road Markings are essential because they:

4.1 Improve Lane Discipline

Prevent drifting and side-swipe collisions.

4.2 Regulate Overtaking

Reduce head-on crashes in low-visibility areas.

4.3 Enhance Night & Fog Visibility

Support safe navigation during adverse weather.

4.4 Improve Traffic Flow

Enable smoother merging and diverging movements.

Order on the road reduces chaos—and chaos carries economic and human costs.

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5. Colour Coding of Longitudinal Markings (IRC:35)

IRC:35-2015 specifies uniform colour codes:

White

• Lane lines
• Centre lines
• Permissible crossings

Yellow

• No-overtaking zones
• Median markings

Red / Purple

• High-risk conflict areas

Blue

• Bus Rapid Transit (BRT) lanes

Green

• Non-motorised corridors such as cycle tracks

Uniform colour interpretation prevents confusion across states and regions.

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6. Road-Wise Application Guidelines

6.1. Undivided Roads

• Width < 5.5 m → Centre line generally not required
• 5.5 m – 7.0 m → Single centre line recommended
• 7.0 m with shoulders → Double lines and no-overtaking markings

6.2. Divided Carriageways

Standard marking pattern:

• Normal marking → 3 m line + 6 m gap
• Warning marking → 3 m line + 3 m gap
• Continuous edge lines typically 150 mm wide (urban roads)

6.3. One-Way Roads, Ramps & Slip Lanes

• Continuous edge lines on narrow ramps
• Lane separation lines on multi-lane ramps
• Warning lines before merges

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7. Materials Used for Longitudinal Road Markings

IRC:35-2015 recommends durable materials such as:

7.1 Thermoplastic Markings

• High durability
• Excellent retroreflectivity
• Widely used on highways

7.2 Road Marking Paint

• Cost-effective
• Suitable for temporary works

7.3 Cold Applied Plastic

• Ideal for heavy traffic corridors

7.4 Preformed Adhesive Tapes

• Fast installation
• Useful in specialised zones

Material selection directly influences durability and compliance with Pavement Marking Standards.

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8. Retroreflectivity & Visibility Standards

To ensure nighttime performance:

• Glass beads are embedded for retroreflection
• Minimum preview distance based on speed:
  
  • 30 km/h → ≥ 17 m
  • 120 km/h → ≥ 67 m

Adequate preview distance ensures safe driver reaction time.

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9. Integration with Road Studs

IRC recommends combining markings with reflective studs:

• White studs → Lane lines
• Red studs → Left edge
• Yellow studs → Medians
• Green studs → Exit edges

This improves visibility during rain, fog, and low-light conditions.

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10. Compliance & Regulatory Framework

Longitudinal Road Markings must comply with:

• IRC:35-2015
• MoRTH Clause 803 specifications

Periodic inspections and structured audits are essential to maintain national-level consistency and safety performance.

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11. Final Thoughts

Longitudinal Road Markings may appear simple, yet they are powerful safety instruments. When implemented according to IRC:35-2015, they ensure:

• Safer highways
• Improved lane discipline
• Reduced accident risk
• Enhanced driver comfort
• Nationwide uniformity

With increasing traffic density, strict adherence to Pavement Marking Standards is critical for saving lives and strengthening Road Safety Engineering practices across India.

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12. RoadvisionAI and Smarter Road Compliance

roadvisionai supports compliance with IRC:35-2015 through AI-powered monitoring solutions such as Pavement Condition Intelligence Agent and AI road marking inspection systems.

Automated pavement surveys help detect:

• Faded lane markings
• Surface cracks
• Potholes
• Retroreflectivity loss

By enabling timely maintenance and real-time assessment, roadvisionai strengthens accountability, improves infrastructure durability, and enhances overall road safety performance.

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FAQs

Q1. What are longitudinal road markings?
Longitudinal Road Markings are pavement lines laid parallel to traffic flow that guide lane discipline, regulate overtaking, and enhance safety as defined under IRC:35-2015.

Q2. What types are specified in IRC:35?
Broken lines, single continuous lines, double continuous lines, combination lines, warning lines, centre lines, and edge lines.

Q3. Where are they commonly used?
They are applied on highways, expressways, arterial roads, ramps, and urban corridors to ensure organised and safe traffic movement.

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