Formation_(rail)

Subgrade

Subgrade

Material underneath a road or track

In transport engineering, subgrade is the native material underneath a constructed road,[1] pavement or railway track (US: railroad track). It is also called formation level.

Layers in the construction of a mortarless pavement: A.) Subgrade B.) Subbase C.) Base course D.) Paver base E.) Pavers F.) Fine-grained sand
Section through railway track and foundation showing the sub-grade

The subgrade provides support to the subbase level and acts as an integral load-bearing layer. Failure of the subgrade can cause depressions and rutting of the upper base and surface courses. These in turn can lead to water pooling in deformations and cause vehicle aquaplaning among other issues.[2]

The term can also refer to imported material that has been used to build an embankment.

Construction

Subgrades are commonly compacted before the construction of a road, pavement or railway track. This is to ensure their ability to absorb the loads being transferred down from the upper layers, increasing the life and wear of the surface courses.

See also

References

  1. [1]
    http://www.highwaysmaintenance.com/drainage.htm The Idiots' Guide to Highways Maintenance highwaysmaintenence.com
  2. [2]
    "Ruts Cause Hydroplaning Accidents". www.atlantaeng.com. Retrieved 2024-02-09.
Share this article:

This article uses material from the Wikipedia article Formation_(rail), and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.