Bridge or Gantry Buffers. (a) If there is more than one crane on the same runway, buffers or other cushioning devices shall be placed between the cranes at both ends of the bridges or gantries. (b) Buffers shall have energy absorbing capacity to stop the crane when traveling at a speed of at least 40 percent of rated load speed, but the average deceleration rate shall not exceed 3 feet per second