usable length

例句：

1. 1. The new model car has a usable length of 400 kilometers.
   这款新型汽车的可利用长度为400公里。
2. 2. The project requires a usable length of 500 meters for the road.
   该项目需要500米长的路段作为道路。
3. 3.The engineer calculated the usable length of the bridge based on its load capacity.
   工程师根据桥梁的承载能力计算了桥梁的有效长度。