A protective layer of fine, compacted material installed between the raw earth subgrade and the crushed stone ballast. It prevents clay and mud from pumping up into the clean ballast under the heavy, repetitive pounding of passing trains. Proper blanketing ensures the track structure drains well and maintains its geometry.
Heard on the job
The mud spots are getting worse through the curve, so the track gang is going to dig it out and put down new blanketing.
Also heard as
- sub-ballast