Federal investigators said yesterday that the gasoline tanker that plunged from an overpass onto Interstate 95 in January was missing part of a spring from a rear axle, indicating for the first time that mechanical failure may have played a role in the crash.
The National Transportation Safety Board said that a leaf spring on the right rear axle of the tanker was broken and that part of it was missing. Investigators were trying to determine whether the spring was damaged before the crash Jan. 13. They said they could not find the missing piece in the wreckage.
They also reported yesterday that the truck's transmission was found to be in "eight-speed high gear" after the crash. Industry experts said that the tanker probably had about 12 gears and that eighth gear indicates a moderate rate of speed, perhaps about 40 mph. The speed limit on the ramp from which the truck fell was 45 mph.
Witnesses to the crash have told authorities that the tanker was moving erratically, though not speeding, moments before it fell from a bridge that carries Interstate 895 over I-95 in Howard County. The tanker fell rear-end-first onto I-95, causing an explosion that killed four people, including the tanker driver.
Two witnesses also said they saw the driver, Jackie M. Frost of Finksburg, slumped forward before the crash. The NTSB said yesterday that it has received those reports and is weighing them against other evidence. Toxicology tests on Frost's body were negative for alcohol, illegal drugs and medications that cause drowsiness, the agency reported.
NTSB spokesman Ted Lopatkiewicz said it is too early for investigators to begin focusing on one avenue of inquiry. He declined to speak about the significance of the missing leaf spring.
"Because it was not found in the wreckage, it's something to document," he said. "We try to cross every T. It's one of the reasons our investigations take as long as they do."
The wreckage from the crash remains in a state warehouse by the Key Bridge, where the federal investigators and the Maryland Transportation Authority Police have been piecing together the events that led to the accident.
The NTSB said it took the remaining section of the main leaf spring to its materials lab in Washington, where it will try to determine when the damage was caused. The right rear of the truck went over the wall first. If a right rear spring were broken or missing, the wheel and tire closest to it could have had freer movement because they lacked the dampening effect a spring provides.
The company that owned the tanker, Petro-Chemical Transport of Addison, Texas, declined to comment yesterday. It said it has an agreement with the NTSB not to comment until the investigation is complete, likely sometime next year.
Frost, who was 64, had worked for the company for 10 years when he filled his tanker with 8,900 gallons of premium Citgo gasoline on Jan. 13. He left the fuel terminal in south Baltimore and headed west on I-895 toward I-95. His destination was the National Naval Medical Center in Bethesda.
But as the tanker climbed the ramp to I-95, it apparently scraped along a barrier for at least 50 feet before plunging into traffic below. Four vehicles and the tanker were consumed by the enormous fireball ignited by the load of gasoline.
The driver of only one of the vehicles, a tractor-trailer, survived. The other four drivers were killed, probably instantly. In addition to Frost, the others killed in the crash were Marc Baladi, 63, of Baltimore; Maurice Durschlag, 62, of Glen Burnie; and Rita A. Gall, 42, of Lansing, Mich.