在同一建筑物内,同层、上下层、或上、中、下三层设置轨道运行式起重机的情况下,会发生起重机之间以及吊着的重物或吊钩与下层起重机碰撞的情况。靠起重机驾驶员用目测防止碰撞的事故是困难的。目前国外已采用了超声波、光线、雷达等防碰撞装置,而我国直 In the same building, the same floor, the upper and lower levels, or the upper, middle and lower levels set up a rail-mounted crane, the cranes and hanging weights or hooks collide with the lower crane. It is difficult for a crane driver to visually detect a collision to be avoided. At present, foreign countries have adopted ultrasonic, light, radar and other anti-collision devices, while our country straight