I've seen propane torches used as an alternative weed control method (called "flame weeding"), though I'm not aware of any railroads doing this yet. Just a few second of exposure to flame is enough to kill most herbaceous vegetation.
EDIT: Live steam ("steam weeding") would probably work just as well as flames, and would be safer in dry seasons when fire danger is high. It appears to be big in Australia, perhaps for that reason.
-Philip Marshall
Edited 2 time(s). Last edit at 06/23/2014 11:40PM by philip.marshall.