Highway Accident Report

Adopted: May 24, 1973
U.S. ROUTE 501,
March 9, 1972

NTSB Number: HAR-73/03
NTIS Number: PB-221986
PDF Document (2.28 MB)


This report describes and analyzes the overturn of a tractor-semitrailer (tank) carrying liquid propane under pressure on U.S. Route 501 near Lynchburg, VA, on March 9, 1972. After overturning, the vehicle slid on its side and struck a rock embankment, which ruptured the tank shell and permitted the propane to escape. When the propane-air mixture ignited, two persons, including the truckdriver, were killed, and five others were injured.

The National Transportation Safety Board determines that the cause of the overturn was the driving of the tractor-semitrailer on the wrong side of the road, and a subsequent evasive steering action which exceeded the limited capability of the truck to resist overturn. Contributing factors included a misleading traffic-control sign, an inadequate road-marking system, and the high center of gravity of the truck. The causes of the burn fatalities and injuries were rupture of the tank at a point susceptible to rupture and the inadequacy of the required placards as a means of warning bystanders of the nature and range of the hazard.

The report contains recommendations to various Federal, State, and industry authorities intended to prevent the recurrence of this type of accident.