Noun
railbed (plural railbeds)
The substructure of a railway, underlying the tracks; the roadbed of a railroad.
Originally a railbed that serviced an electric railway that went through Albion, the Rail Trail is now a trail from which you can access almost all of the other trails off of, almost like a highway. Source: Internet
They were responsible, according to sources, for ensuring that a replacement rail, now considered a possible cause of the derailment, was secured in the railbed. Source: Internet