在高速上就是小车刹车距离也要几十米，更不要提大车了。高速上不是你想刹车就能刹住的, 再加上反映时间。等你看到前面有车时是

避免不了相撞的。

http://www.racemath.info/motionandenergy/stop_distance.htm

The table shows typical stopping distances included in the Highway code

Speed (mph)	20	30	40	50	60	70	80
Thinking Distance (m)	6	9	12	15	18	21	24
Braking Distance (m)	6	14	24	38	54	75	96
Total Stopping Distance (m)	12	23	36	53	72	96	120