12-04-2012, 03:08 PM
HIGHWAY DRAINAGE
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HIGHWAY DRAINAGE
Highway drainage is the disposal of rainwater, achieved by a network of watercourses of various types. The law on drainage responsibilities is complicated and many people are unaware of its existence.
HIGHWAY DRAINAGE DESIGN | HIGHWAY DRAINAGE STRUCTURES
Includes collecting, transporting, and disposing of surface/subsurface water originating on or near the highway right of way or flowing in streams crossing bordering that right of way.
Drainage of highway is important because water damage highway structure in many ways. The water which are dangerous for highways are:
Rainwater: Cause erosion on surface or may seep downward and damage pavement (surface drains)
Pavement and shoulder
The highway engineer should ensure that the precipitation is removed from the pavement as soon as possible and that highway drainage is done efficiently. Water that falls on the road way follows laterally or obliquely from it, under the influence of cross slope. Or superelevation in pavement and shoulder. A suitable value of cross fall for paved roads is about 3% for carriage way with a slope of 4-6% for shoulders. And increased cross fall for the carriage way e.g. 4% is desirable if the quantity of the final shape of the road surface is likely to be low for any reason,
DRAINAGE WITH PAVEMENT LAYERS:
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Is an essential element of structural design because the strength of the subgrade used for design purposes depends on the moisture content during the most likely adverse conditions. It is evident that benefits are derived from applying steeper cross falls to layers at successive depths in the pavement.
ROAD-WAY DRAINAGE IN URBAN AREAS:
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Water falling on the road surface generally flows along the gutter to curbs or gutter inlets and from them to underground storm drains.
• Expensive as compared to rural area drainage works.
• We have certain justification i.e. large volume of traffic, pedestrian’s property.
• Designed to limit the spread of water over the traveled lanes to some arbitrary maximum.
• Inlets at low points should be designed for longer return period.
WHO IS RESPONSIBLE FOR CULVERTS WHICH RUN UNDER OR WITHIN THE HIGHWAY?
Hampshire County Council is responsible for culverts and most of the bridges over watercourses and rivers associated with the highway. There are exceptions where bridges are privately owned such as those managed by British Waterways.
• WHAT IS A YARD GULLY?
A yard gully is a drainage pit covered by an open metal grating located adjacent to building or in the centre of a yard. It’s purpose is to drain rain water from buildings and yards associated with buildings.
Responsibility: typically the landowner.
• WHAT IS A CULVERT?
A culvert is a large pipe or channel carrying water underground. Hampshire County Council is responsible for culverts and most of the bridges over watercourses that run under the Highway. There are exceptions where bridges are privately owned such as those managed by British Waterways.