The Journey of Longitudinal Road Markings: Types and Uses Explained with IRC Code 35

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Understanding the science behind road safety begins with road markings. One of the most fundamental elements ensuring smooth and safe traffic movement is the system of longitudinal road markings, meticulously laid out in IRC Code 35:2015. These lines, symbols, and colors on the pavement are more than just paint — they are a language that communicates critical information to drivers, helping manage traffic flow, reduce accidents, and improve road discipline.

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In this blog, we delve deep into longitudinal markings under IRC Code 35, their classification, types, purpose, color codes, and applications across different road categories in India.

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What is IRC Code 35?

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IRC:35-2015, the Code of Practice for Road Markings, is issued by the Indian Roads Congress (IRC). It sets standardized guidelines for the selection, application, and maintenance of road markings across the country, including both rural and urban roads.

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What Are Longitudinal Road Markings?

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Longitudinal road markings are lines drawn parallel to the direction of traffic. According to IRC Code 35, they help guide traffic flow, enforce lane discipline, restrict overtaking where necessary, and improve safety on curves and high-speed corridors.

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They are crucial for:

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• Indicating lane boundaries

• Marking center lines

• Creating no-overtaking zones

• Guiding vehicles through curves and intersections

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Classification of Longitudinal Markings under IRC Code 35

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IRC Code 35 defines various longitudinal markings under the abbreviation LM. These include:

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1. Broken Lines (LM01, LM02)

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• Indicate lane separation on roads where overtaking is permitted.

• Common in normal traffic conditions.

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2. Single Continuous Lines (LM21, LM22)

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• Used to prohibit lane changes or overtaking at certain hazardous stretches.

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3. Double Continuous Lines (LM23, LM24)

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• Serve as a strict no-overtaking zone.

• Typically used at dangerous curves or near intersections with poor visibility.

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4. Combination Lines (LM28, LM29)

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• One continuous + one broken line.

• Used to restrict overtaking for vehicles on one side only, while allowing it on the other side.

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5. Warning Lines (LM04, LM05)

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• Broken lines with a higher marking-to-gap ratio.

• Serve as a caution zone ahead of a no-overtaking section.

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Purpose of Longitudinal Markings

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• Lane Discipline: Ensures vehicles stay within designated lanes, reducing side-swipe accidents.

• Overtaking Regulation: Warns and prevents overtaking at unsafe stretches.

• Visibility Aid: Assists drivers during nighttime and in adverse weather.

• Traffic Flow Management: Smoothens merging and diverging lanes.

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Color Coding in Longitudinal Markings

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IRC 35 defines colors for specific purposes:

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• White: Standard for lane markings, centerlines in single carriageways, and permissible crossing.

• Yellow: Indicates prohibition zones (e.g., double yellow lines = strict no-overtaking).

• Red/Purple: Used at high-risk areas to alert drivers.

• Blue: Reserved for special purpose lanes like public transport or bus rapid transit systems.

• Green: Designated for non-motorized transport (like bicycles).

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Types of Roads and Their Marking Guidelines (As per IRC 35)

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1. Undivided Roads

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• <5.5 m wide: Center line generally not recommended unless at intersections or fog-prone areas.

• 5.5 to 7 m wide: Single broken or continuous line used for center marking.

• >7 m with paved shoulders: Double yellow lines or ladder hatching used in no-overtaking zones.

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2. Divided Carriageways

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• Lane lines marked at 3m line + 6m gap (normal) and 3m line + 3m gap (warning).

• Edge lines are continuous and are typically 150 mm wide in urban areas.

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3. One-Way Streets/Ramps/Slip Roads

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• Narrow ramps use LM24 edge lines.

• Two-lane ramps use LM07/LM08 and switch to warning or no-overtaking lines when required.

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Material Used for Longitudinal Markings

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As per IRC 35 Section 2:

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• Thermoplastic Material: Most widely used due to fast drying, durability, and reflectivity.

• Paint (Water/Solvent-based): Cheaper but less durable; used for temporary markings.

• Cold Applied Plastics: Ideal for audible raised lines and durable under heavy traffic.

• Preformed Adhesive Tapes: High initial cost but excellent for short-term, high-visibility needs.

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Visibility and Retroreflectivity

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To ensure visibility in all conditions:

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• Glass beads are embedded for retroreflectivity.

• Line width and reflectivity are designed based on road speed:
  • At 30 kmph: preview distance should be ≥17m
  • At 120 kmph: preview distance should be ≥67m

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Road Stud Integration

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IRC recommends integrating road studs with longitudinal markings:

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• White studs for lane lines

• Red for left edge, Yellow for median

• Green at safe crossable edges (like exits)

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Compliance and Maintenance

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To retain their effectiveness:

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• Markings must undergo periodic safety audits

• Materials and installation must follow IRC:35 and MoRTH Clause 803

• Markings must remain uniform across regions to ensure driver comprehension

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Final Thoughts

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Longitudinal road markings, though simple in appearance, are a critical aspect of road safety infrastructure. IRC Code 35 provides a comprehensive guideline for their design, application, and maintenance. With increasing vehicular density in India, adherence to these standards is not just important — it is essential for saving lives and improving commute efficiency.

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FAQs

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Q1. What are longitudinal road markings and why are they important?

Longitudinal road markings are continuous or broken lines that run parallel to the direction of traffic. They guide lane discipline, regulate overtaking, and enhance road safety under the guidelines of IRC Code 35.

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Q2. What types of longitudinal markings are specified in IRC Code 35?

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IRC Code 35 specifies types like center lines, lane lines, edge lines, and continuity lines. These markings help separate opposing traffic, indicate lane boundaries, and support smoother traffic movement.

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Q3. Where are longitudinal markings most commonly used?

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They are widely used on highways, arterial roads, and urban streets to provide visual guidance and promote safer driving behavior.