机走线或机回线，全称机车走行线或机车回送线，是指铁路车站站场内用于机车转场或折返的铁道。一些尽头站（例如中国铁路总公司的青岛站与北京站）设置有机走线，供终到的旅客列车的牵引机车返回机务段。

A headshunt (or escape track in the United States) is a short length of track provided to release locomotives at terminal platforms, or to allow shunting to take place clear of main lines.