An inattentive driver and faulty brakes, due to an improperly maintained vehicle, were the probable cause of an accident in which a heavy commercial truck struck a California-bound Amtrak passenger train in the Nevada desert last summer killing six and injuring 16, according to the National Transportation Safety Board (NTSB).

On Friday, June 24, 2011, a 2008 Peterbilt truck-tractor pulling two empty trailers on northbound U.S. 95 struck the left side of an Amtrak train that was passing through a grade crossing en route from Chicago to Emeryville, Calif. The collision, which destroyed the truck-tractor and several passenger railcars, also ignited a fire that engulfed two railcars and part of a third. The accident killed the truck driver, the train conductor and four train passengers; 15 train passengers and one crewmember were injured.

When the grade crossing signals activated, the truck, traveling at least 58 mph, was still more than 2,300 feet from the tracks, however, investigators found no evidence that the truck driver began braking until the front of the truck was less than 300 feet from the crossing.

Reconstruction of the accident using a recording from a forward-facing video camera mounted on the front of the train as well as physical evidence helped investigators to determine that the truck struck the crew car of the train at 26 mph to 30 mph.

The investigation revealed that nine of the 16 brakes on the truck were either out-of-adjustment or inoperative. In addition, the anti-lock brake systems of both trailers were not functional; wires to missing sensors were cut and zip-tied and wires to malfunction indicator lights had been disconnected, raising serious questions about the maintenance practices of the trucking company.

Several months after the collision, NTSB investigators returned to the accident site and conducted a series of tests with an exemplar truck in which the braking system was in proper working order. Test results showed that if the accident truck been able to decelerate as well as the exemplar vehicle, the accident would have been avoided with the accident truck coming to a stop 15 feet to 67 feet short of the rail tracks.

Investigators also found that the driver, who had an erratic employment history with as many as 30 jobs over the 10 years prior to the accident, had been cited for more than a dozen moving violations, had at least three accidents, and had his driver's license suspended or revoked at least four times. When he applied to work at John Davis Trucking, he omitted information and misrepresented parts of his employment history. The NTSB concluded that since the process in place to obtain a full employment and driver license history was inadequate, John Davis Trucking did not have sufficient information to make an informed hiring decision when considering the driver's application.

As a result of the investigation, the NTSB made a total of 20 safety recommendations to John Davis Trucking, the Federal Motor Carrier Safety Administration, the National Highway Traffic Safety Administration, the Federal Highway Administration, the Federal Railroad Administration, the Nevada Highway Patrol, the Commercial Vehicle Safety Alliance, the American Trucking Association, The Owner-Operator Independent Drivers Association, the Towing and Recovery Association of America, the American Bus Association and the United Motorcoach Association.

A synopsis of the NTSB report, including the probable cause, findings and a complete list of the safety recommendations, is available here.