E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
E01B3/00—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails
E01B3/28—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails made from concrete or from natural or artificial stone
E01B3/38—Longitudinal sleepers; Longitudinal sleepers integral or combined with tie-rods; Combined longitudinal and transverse sleepers; Layers of concrete supporting both rails