NTSB Number: HAR-76/07 NTIS Number: PB-257913/ASSYNOPSIS
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)"