This equipment uses a series of independently controlled high amplitude drop hammers to smash the slab. Typically, there are between 12 and 16 hammers, each weighing between 1,000 to 1,500 lbs. Hammers can be dropped from variable heights 1 to 5 ft. to create impact energies between 2,000 to 12,000 ft.-lbs. Hammers cycle at a rate of 30 to 35 impacts per minute. MHBs can rubblize an entire lane up to 13 ft. in a single pass (Antigo Construction, 2001). Figure 7-8 shows a typical multi-head breaker.