Components, systems and materials › Road furniture and safety › Delineator
Delineator
What it is
A delineator is a post or device carrying a retroreflector that marks the edge and alignment of a road so that drivers can see where it goes, especially at night, in rain and in fog.
Where it is used
Horizontal curves, high embankments, bridge and culvert approaches, medians, narrow sections and hill roads with steep drops.
How it works
Retroreflective sheeting returns light from a vehicle's headlights back towards the driver. A row of delineators therefore traces the road edge far beyond the area lit by headlights, showing the curve ahead early enough to slow down. Different colours on left and right help drivers stay in lane.
Types
- Roadside guide posts
- barrier-mounted delineators on crash barriers and parapets
- chevron alignment boards on sharp curves
- flexible spring-back posts for medians and work zones
Materials
Plastic, concrete or steel posts; high-intensity or prismatic retroreflective sheeting; mounting brackets.
Spacing reduces as curve radius decreases, so that several delineators are always visible on a curve. Height above road level and lateral offset follow the national guideline. Sheeting grade is chosen for the road class, and posts should be forgiving so they do not become hazards when struck.
Installation and QA steps
- Set out locations from the curve radius and guideline spacing.
- Install posts vertically at the correct height and offset.
- Check at night from a vehicle that the line reads clearly.
- Clean sheeting periodically and replace damaged or missing posts.
- Dirty or faded sheeting that no longer reflects
- posts knocked down and not replaced
- irregular spacing that misleads drivers about curvature
- rigid posts that injure riders when struck
Codes cited
- IRC:79 (India): Recommended practice for road delineators.
Cited by number only. We do not reproduce code text, tables or figures.
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