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Components of highway drainage system

Short answer

Highway drainage components include camber, shoulders, side drains, catch drains, mitre drains, cross-drainage structures, sub-surface drainage, erosion control works, urban components like gullies and storm sewers, and disposal outlets. Together they remove surface and ground water safely. Each component prevents water from damaging the road.

What are the components of the highway drainage system?

The components of a highway drainage system are:

  1. Camber and cross-slope of the carriageway and shoulders: first stage of removing the surface water.
  2. Side drains (longitudinal drains): open or lined drains along the road edge; kerb and channel in urban areas.
  3. Catch / intercepting drains: above cut slopes to stop hill-side runoff reaching the road.
  4. Mitre (turnout) drains and outfalls: take water from side drains into natural ground.
  5. Cross-drainage structures: culverts, causeways, minor bridges (and inverted siphons or aqueducts where needed).
  6. Sub-surface drainage: trench drains with perforated pipe, drainage blankets, cut-off layers, horizontal drains and weep holes in retaining walls.
  7. Erosion control and energy dissipating structures: check dams, drop structures, aprons, rip-rap, stilling basins, bio-engineering.
  8. Urban components: gully inlets, catch basins, storm sewers and manholes.
  9. Disposal: natural streams, soak pits or storage ponds.

✓ Answer checked by Claude Opus 5.5 (high effort)

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