 An emergency brake engages if the air pressure needed to control the incline is insufficient ; the brake also engages if a dead man 's switch is tripped in the operator 's booth . In addition to the hauling cables , a 972 @-@ foot ( 296 m ) safety cable capable of withstanding 165 short tons ( 149 @.@ 7 metric tons ; 147 @.@ 3 long tons ) is also connected to the cars . 
