In early afternoon, a northbound tractor-semitrailer with horizontally mounted tubes filled with compressed hydrogen at approximately 2400 psi (166 bar) was struck by a northbound pickup truck that veered into the semitrailer's right rear axle. According to witnesses, the tractor-semitrailer then went out of control and left the roadway, coming to rest approximately 300 feet (91 meters) from the point of impact. As a result of rotational torque and impact, the end of one tube was sheared off at the bulkhead and left the tube bundle. During the process, some of the tubes, valves, piping, and fittings at the rear of the semitrailer were damaged and released hydrogen. The hydrogen ignited and burned the rear of the semitrailer. In the meantime, the pickup truck had also run off the view more