Subgrade

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 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

gollark: Oh, and my city's subway system is running a reduced service, but for some reason the train network is running exactly the same as usual with probably a fifth of the usual passengers on my line.
gollark: My school is planning to try online learning or something, which I am sure will go badly.
gollark: ```What will happen about exams?In England and Wales, all exams in May and June have been cancelled, including GCSEs, A-levels and primary school national curriculum tests known as Sats.Mr Williamson told the Commons on Wednesday: "I can confirm we will not go ahead with assessments or exams and that we will not be publishing performance tables for this academic year."We will work with the sector and [the exams watchdog] Ofqual to ensure children get the qualifications that they need."```- from the BBC
gollark: Not really.
gollark: The wording is a bit ambiguous so in theory they might be planning to do them later, but it seems like they're being cancelled.

See also

References
  1. http://www.highwaysmaintenance.com/drainage.htm The Idiots' Guide to Highways Maintenance highwaysmaintenence.com
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.