Highway drainage
Contents |
[edit] Introduction
The construction of roads affects the natural surface and subsurface drainage pattern of watersheds or hill-slopes. The provision of adequate drainage is important to prevent the accumulation of excess water or moisture on or within road constructions that can adversely affect their material properties, compromise overall stability and affect driver safety. Drainage must cope with water from the carriageways, hard shoulders, foot/cycle paths, verges, and adjacent catchment areas.
The design of highway drainage will depend on several factors, including:
- The intensity of rainfall expected.
- The size of catchment area.
- The permeability of the surfaces.
The road camber or cross-fall should be designed to cope with heavy water run-off. Insufficient cross-fall can increase the risk of vehicles skidding or aquaplaning on the surface water. The standard cross-fall for roads is usually taken as 1:40, although the camber will vary depending on the individual requirements of the road.
[edit] Urban roads
Surface water is generally collected in channels at the road-side and discharged through gullies (drainage gratings at the edges of the road) into storm water sewers. Gullies are typically positioned at intervals of 25-30 m, depending on the road width and nature of the cross-fall. Gully covers can be either top opening or side opening.
To reduce the number of required drainage points, pavings and verges should be graded towards the channel.
Culverts may also be used. A culvert is a closed conduit or tunnel used to convey water from one area to another, normally from one side of a road to the other side.
For more information, see Culvert.
[edit] Rural roads
Minor roads usually use simple openings or channels which feed into roadside ditches.
Most main roads use a system of gullies and piped sewers. However, soakaways may also be used to discharge water, these are large underground chambers into which water flows from a gully. Water collects and gradually soaks through holes into the surrounding ground or to streams and roadside ditches.
For more information, see Soakaway.
For roads with hard shoulders, it is usual for the kerb to be kept flush with the road surface, with a precast concrete channel placed at the outside edge to drain water. This channel discharges water into gullies.
[edit] Related articles on Designing Buildings Wiki:
- Bituminous mixing and laying plant.
- Catchment flood management plans.
- Code of Practice for Ironwork Systems Installation and Refurbishment.
- Drainage.
- Gulley.
- Highway engineers and drainage.
- Infrastructure.
- Kerbs.
- Manhole.
- Manhole cover.
- Overview of the road development process.
- Pavement.
- Planning for floods.
- Pumps and dewatering equipment.
- Road construction.
- Road improvement scheme consultation.
- Road joints.
- Runway construction.
- Section 50 agreement.
- Sewer construction.
- Soakaway.
- Successful road kerb trial.
- Sustainable urban drainage systems SUDS.
- Types of road and street.
- Water engineering.
[edit] External references
- ‘Introduction to civil engineering construction’ (3rd ed.), HOLMES, R., The College of Estate Management (1995)
- ‘Building Construction Handbook’ (6th ed.), CHUDLEY, R., GREENO, R., Butterworth-Heinemann (2007)
Featured articles and news
Introducing or next Guest Editor Arun Baybars
Practising architect and design panel review member.
Quick summary by size, shape, test, material, use or bonding.
Types of rapidly renewable content
From forestry to agricultural crops and their by-products.
Terraced houses and the public realm
The discernible difference between the public realm of detached housing and of terraced housing.
Put digitalisation and sustainability at the core of curricula
Project management educators are urged.
Looking back at the influence of climate events
From a designer and writer: 'There are limits to growth but no limits to development'.
Terms, histories, theories and practice.
Biophilic design and natural light
Letting in the light and natural elements into spaces.
APM Programme Management Conference 2024
Strategies for Success.
Residential takes the reins as contract awards even out
Contracts down, but remain above the last quarter of 2023.
Celebrating Eid and the largest mud-brick building.
Barry Kingscote claims prestigious CIOB CMYA Award.
The British Mosque: an architectural and social history
The story of some 1,500 mosques or more in Britain.
Heat pump refrigerants, efficiencies and impacts
R12 to R1270 what are the differences?
Global heat pump market in 2023
Challenging times with positive but modest outlook.
Beyond the infrastructure pipeline
Opportunities and chokepoints.