Abstract: At approximately 5:00 p.m. on October 12, 1998, Employee #1, a welder, Employee #2 and three coworkers were riding on a sled being pulled by a 1974 Caterpillar 583H pipelayer, serial #61A-904. The crew had completed a tie-in weld at a spot west of access road #14 and were headed to the next work site. They traveled approximately 1,000 ft to the west along the row before stopping at a large rock in the middle of the row. They dismounted the sled so it could travel unimpeded over the large rock, then remounted to continue on. The pipelayer and sled had resumed travel for only about 3 ft when the boom of the pipelayer fell backward. The 500 lb block and hook hit the right side of the sled and struck Employee #1 on the head. The coworkers, who had escaped from the sled, assisted Employee #1 and called for medical care. The foreman, who had been observing the crew riding the sled and saw the boom fall, drove to the scene from the access road. Employee #1 was moved into his vehicle and transported to meet medics and an ambulance. He was transported to Weeks Memorial Hospital in Lancaster, NH, where he was pronounced dead at 7:00 p.m. Employee #1 had suffered a fractured jaw, a fractured neck, and massive internal injuries from being struck in the chest by the hook and block. Employee #2 sustained chest abrasions and contusions in a fall connected to the accident; he was treated and released.