road.bed

roadbed的音标和读音：
DJ音标发音： [ˈroudˌbed]
KK音标发音： [ˈrodˌbɛd]

roadbed的词性：
n.（名词）

1. 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

2. A layer of ballast directly under the ties.
道碴：直接铺在枕木下的石碴

3. The foundation and surface of a road.
公路地基和公路路面