Introduction to Road Markings | Civil Engineering Optional Notes for UPSC PDF Download

Introduction to Road Markings

• Road markings refer to the lines, patterns, words, and colors applied on or attached to the road surface, kerbs, or objects near the carriageway.
• Their primary purpose is to control, warn, guide, and inform road users.
• Road markings play a crucial role in: 
  • Guiding and controlling traffic on highways 
  • Delineating the traffic path and providing lateral clearance from hazards 
  • Channelizing pedestrian and cyclist movements into safe locations 
  • Comprising longitudinal, transverse, text, and symbol markings

Significance of Road Markings

• Bare roads without markings can lead to vehicular confusion and chaos.
• Markings help direct, guide, and regulate road users.
• They supplement the messages conveyed by road signs and other traffic devices.
• Road markings promote road safety and ensure smooth traffic flow.

Basics of Retro-Reflective Technology

• Luminance is the measure of light emitted or reflected from a surface, expressed in candelas per square meter (cd/m²).
• Key units of measurement: 
  • Intensity of a light source: Candela (cd) 
  • Illuminance: Light falling on a surface (lux) 
  • Luminance: Light coming from a surface via diffuse reflection (daytime) or retro-reflection (nighttime), expressed in cd/m²/lux
  • Coefficient of retro-reflection (RL): Luminance/Illuminance (cd/lux/m²)
    
    
• Retro-reflection is the mechanism by which vehicle headlamps are reflected back toward the source (driver) at a very narrow observation angle, improving night visibility.
• Glass beads enhance the retro-reflective properties of road markings.

Current Scenario and Issues

• Poor night visibility and road presence can lead to accident dangers at critical spots.
• Existing specifications in codes of practice are often recipe-based rather than performance-based.

Types of Materials for Road Markings

• Most commonly used for roadways
• A mixture of plasticizers and resins applied in a molten state
• Fast drying time, high durability (2-3 years), and better retro-reflectivity

B. Solvent-Borne and Waterborne Road Marking Paints

• Oldest form of pavement marking materials
• Used for temporary work zone markings and short-term applications
• Waterborne paints are environmentally friendly and easier to handle

C. Cold Applied Plastics

• Suitable for colored pavement markings and audible raised profiles
• More durable than thermoplastics in retaining color and luminance
• No need for large application equipment, easily carried in vans/trailers

D. Preformed Adhesive Tapes

• Available in continuous rolls of various lengths and widths
• No application equipment or experienced operators needed
• No drying or curing period required
• High initial cost but suitable for high-traffic areas requiring frequent replacement

Performance Assessment and Monitoring

• Visibility related to speed (preview distance for driver reaction)
• Retro-reflectivity (RL) for night visibility under dry and wet conditions
• External factors: material composition, application procedure, road surface, traffic presence

B. Wear Durability

• Measured as a percentage of the area remaining intact
• Performance parameter: at least 70% of marking should remain intact for the service life

C. Day Visibility

• Measured based on the luminance coefficient (Qd) under diffuse illumination
• Performance parameter: Qd ≥ 130 mcd/m²/lux for cement roads, ≥ 100 mcd/m²/lux for asphalt roads

D. Night Visibility: Dry Retro-reflection

• Performance parameters based on speed limits and warranty periods (up to 2 years)

E. Night Visibility: Wet Retro-reflection

• A film of water coating the glass beads reduces retro-reflective performance
• Performance parameter: Rw ≥ 100 mcd/m²/lux initially, ≥ 50 mcd/m²/lux minimum threshold

F. Skid Resistance

• Improved by including surface-applied angular particles
• Performance parameter: BPN ≥ 55 initially, ≥ 45 minimum threshold for urban/city roads

Road Marking Evaluation Process

• ≤ 3 km: one randomly located section, sample size of 20 measurements 
• 3-16 km: at least three randomly located sections, sample size of 20 measurements in each section
• For legends, symbols, transverse lines, and pedestrian crossings: • Specific guidelines for evaluation sections and number of measurements

Classification of Pavement Marking

A. Longitudinal Marking (LM)

• Along the traffic movement: center lines, lane lines, edge lines
• Specific guidelines based on road category, carriageway width, and traffic conditions

B. Transverse Marking (TM)

• Across the carriageway for traffic control: stop markings, give way markings

C. Hazard Marking (HM)

• Facilitating traffic merging/diverging, prohibiting cross-over
• Chevron, diagonal, and hatch markings

D. Facility Marking (FM)

• Parking markings, word messages for buses, cyclists, and disabled persons