HIGHWAY ACCIDENT REPORT
Adopted: July 28, 1976
UNION OIL COMPANY OF CALIFORNIA
TANK TRUCK AND FULL TRAILER OVERTURN AND FIRE
ALASKAN WAY VIADUCT,
SEATTLE, WASHINGTON
DECEMBER 4, 1975 
NTSB Number: HAR-76/07
NTIS Number: PB-257913/AS 
SYNOPSIS
About 1 a.m. on December 4, 1975, a 1975 Peterbilt tank truck and a 1970 Peerless full trailer (tank), owned by Union Oil Company of California, went out of control on the Alaskan Way Viaduct in Seattle, Washington, as the driver attempted to negotiate a curve on the traffic-polished concrete roadway at 52 mph and during a rainstorm. The combination vehicle jackknifed and the trailer struck a viaduct support column. The trailer's tank ruptured and its cargo of gasoline spilled. Fire ensued, spread along the viaduct, and spilled to the ground below, where it ignited 4 railroad freight cars, 30 motor vehicles, and adjacent buildings. The accident caused property damage estimated at $750,000. Two firemen were injured while fighting the fire.

The National Transportation Safety Board determines that the probable cause of this accident was the failure of the driver to reduce the speed of the combination vehicle to permit safe negotiation of the curve under existing road and weather conditions. Contributing to the loss of vehicle control was the marginal traction capability of the pavement for the posted speed limit.

RECOMMENDATIONS

As a result of its investigation of this accident, the National Transportation Safety Board submitted the following recommendation to the National Highway Traffic Safety Administration:

"Test and resolve the apparent problem of operating any vehicle combination over the full-speed range and road and weather conditions encountered in normal operations if one of the units is equipped with a Federal Motor Vehicle Safety Standard No. 121 (FMVSS-121) antilock brake system and the other is not. (H-76-28) (Class II, Priority Followup)"

The National Transportation Safety Board submitted the following recommendations to the State of Washington, Department of Highways:

"Conduct skid tests on the viaduct roadway to determine if there is a problem relative to the road surface and, if such is the case; improve the road surface. (H-76-29) (Class II, Priority Followup)

"Post warning signs on the viaduct to advise drivers that the viaduct roadway is slippery when wet. (H-76-30) (Class II, Priority Followup)"