| 释义 |
〔roadbed〕A layer of ballast directly under the ties.道碴：直接铺在枕木下的石碴〔roadbed〕The foundation upon which the ties, rails, and ballast of a railroad are laid.路基：其上可铺铁道的枕木、铁轨和道碴的地基〔subgrade〕The level layer of rock or earth upon which the foundation of a road or railway is laid.路基，地基：在其上铺设路的基础或铁路道碴的岩石或泥土的水平层〔ballast〕Coarse gravel or crushed rock laid to form a bed for roads or railroads.道碴：用来铺公路或铁路路基的粗砂砾或碎石 |