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In transport engineering
Transportation engineering or transport engineering is the application of technology and scientific principles to the planning, functional design, operation and management of facilities for any mode of transportation in order to provide for t ...
, subgrade is the native material underneath a constructed road
A road is a linear way for the conveyance of traffic that mostly has an improved surface for use by vehicles (motorized and non-motorized) and pedestrians. Unlike streets, the main function of roads is transportation.
There are many types o ...
,http://www.highwaysmaintenance.com/drainage.htm The Idiots' Guide to Highways Maintenance ''highwaysmaintenence.com'' pavement or railway track
A railway track (British English and UIC terminology) or railroad track (American English), also known as permanent way or simply track, is the structure on a railway or railroad consisting of the rails, fasteners, railroad ties (sleeper ...
(US: railroad track). It is also called formation level.
The term can also refer to imported material that has been used to build an embankment
Embankment may refer to:
Geology and geography
* A levee, an artificial bank raised above the immediately surrounding land to redirect or prevent flooding by a river, lake or sea
* Embankment (earthworks), a raised bank to carry a road, railway ...
.
Construction
Subgrades are commonly compacted before the construction of a road, pavement or railway trackSee also
*Subsoil
Subsoil is the layer of soil under the topsoil on the surface of the ground. Like topsoil, it is composed of a variable mixture of small particles such as sand, silt and clay, but with a much lower percentage of organic matter and humus, and ...
* Track bed
The track bed or trackbed is the groundwork onto which a railway track is laid. Trackbeds of disused railways are sometimes used for recreational paths or new light rail links.
According to Network Rail, the trackbed is the layers of ballast a ...
References
{{Geotechnical engineering Road transport Pavements Transportation engineering Permanent way