CPC Subgroup
E01B 3/20 Sleeper construction for special purposes, e.g. with openings for ballast working (sleepers for shiftable track for heavy loads E01B23/12)
Full Title
Transverse or longitudinal sleepers (for switches or crossings E01B7/22); Other means resting directly on the ballastway for supporting rails > made from steel > Sleeper construction for special purposes, e.g. with openings for ballast working (sleepers for shiftable track for heavy loads E01B23/12)