DRAINAGE OF ROADS- SUB DRAINS, CULVERTS, DITCHES, GUTTERS, DROP INLETS AND CATCH BASINS

GROUP MEMBERS:MATALA MAYAMBI TRESOR WASEEM AKRAMKANONGA MUNYUNGU ARTHUR

ROAD DRAINAGE

IMPORTANCE OF ROAD DRAINAGE

It is recognised that a road requires a drainage system to deal with stormwater runoff. Therefore, the drainage system becomes an important and integral consideration in the planning and design of road infrastructure.

In order to provide an appropriate and economic drainage system, all road projects, irrespective of location, size, cost or complexity, must consider and address the following aspects:

provision of an acceptable level of flood immunity and accessibility;

impact of flooding of public and private property;

conveyance of stormwater through the road reserve at a

development and environmental cost that is acceptable to the community as a whole;

protection of the roadway asset;

safety of all road users;

pollutant discharge from the road reserve to receiving waters;

land degradation caused by erosion and sedimentation during road construction, operation and maintenance;

any impact on habitats for terrestrial and aquatic flora and fauna;

any impact on the movement of terrestrial and aquatic fauna.

Inappropriate road drainage infrastructure for example, can change the characteristics of a

waterway by altering:

flooding patterns, including flow distribution;

flood heights;

peak water levels;

water velocities, especially through bridges and culverts;

duration of inundation;

erosion and sedimentation patterns;

fauna transfer; and

terrestrial and aquatic fauna habitats.

These changes may create impacts that lead to in service issues that require additional unplanned

investment to address:

Flood mitigation works;

Erosion and sedimentation problems;

Reductions in adjoining land valuations;

Salinity issues; and

Increases in pollutant levels.

CATCH BASIN

A basin, typically with a grated cover, to which surface runoff drains. The basin may be along a curb side or in the middle of a field. The bottom of the basin is typically connected to a drainage pipe, and the basin serves as an inlet to the storm drain system.

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Catch Basin

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CULVERT

A culvert is a drain or pipe that allows water to flow under a road, railroad, trail, or similar obstruction. Culverts differ from bridges mainly in size and construction.

Culverts are generally smaller than bridges, ranging from 0.3-metre (1 ft) pipes to larger reinforced concrete structures. Culverts are typically surrounded by soil.

Culvert Types

box culvert(typ. unsubmerged)

circular culvert(typ. submerged)

Section Views (Looking Downstream)

Transportation routes cross over waterways using either a bridge or a culvert. Culverts come in many sizes and shapes. Shapes may include round, elliptical, flat-bottomed, pear-shaped, and box.

Culverts may be made of concrete, galvanized steel, aluminum, or plastic, typically high density polyethylene.

Plastic culvert liners are also inserted into failing concrete or steel structures in order to repair the structure without excavating and closing the road.

GUTTERS

STREET GUTTER A street gutter is a depression running

parallel to a road designed to collect rainwater flowing along the street and divert it into a storm drain.

A gutter alleviates water buildup on a street, allowing pedestrians to pass without walking through puddles and reducing the risk of hydroplaning by road vehicles.

Depending on local regulations, a gutter usually discharges in a storm drain whose final discharge falls into a detention pond (in order to remove some pollutants by sedimentation) or into a body of water.

RAIN GUTTER A rain gutter is a

narrow channel, or trough, forming the component of a roof system which collects and diverts rainwater shed by the roof.

DITCHES

DITCHES

A ditch is usually defined as a small to moderate depression created to channel water.

A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for plant irrigation. A trench is a long narrow ditch. Ditches are commonly seen around farmland especially in areas that have required drainage, such as The Fens in eastern England and the Netherlands.

Roadside ditches may provide a hazard to motorists and cyclists, whose vehicles may crash into them and get damaged or stuck, especially in poor weather conditions, and in rural areas.