- the bed or foundation structure for the track of a railroad.
- the layer of ballast immediately beneath the ties of a railroad track.
Examples from the Web for roadbed
Ralph was so dazed that he could barely collect wit and strength in an endeavor to crawl out of the roadbed.Ralph, the Train Dispatcher|Allen Chapman
Engines were overhauled, rolling stock touched up, roadbed put in shape, everything shaken from end to end.Held for Orders|Frank H. Spearman
There was no place but the bottom of the notch, and that was barely wide enough for the roadbed.
The roadbed was as smooth as glass, the rail set flush with it.The Onslaught from Rigel|Fletcher Pratt
While most of the roadbed will be entirely new work, it will not be of heavy construction, the country being comparatively flat.Third Biennial Report of the Oregon State Highway Commission|S. Benson, W. L. Thompson, R. A. Booth, Herbert Nunn