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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.
Background
[edit]According to Network Rail, the trackbed is the layers of ballast and sub-ballast above a prepared subgrade/formation (see diagram). It is designed primarily to reduce the stress on the subgrade.
Other definitions include the surface of the ballast on which the track is laid,[1] the area left after a track has been dismantled and the ballast removed[1] or the track formation beneath the ballast and above the natural ground.[2]
The trackbed can significantly influence the performance of the track, especially ride quality of passenger services.