Highway Accident Report

COLLAPSE OF NEW YORK THRUWAY(I-90) BRIDGE
SCHOHARIE CREEK
NEAR AMSTERDAM, NEW YORK
APRIL 5, 1987

NTSB Number: HAR-88/02
NTIS Number: PB88-916202


SYNOPSIS

On April 5, 1987, two spans of the New York State Thruway (1-90) bridge over the Schoharie Creek fell about 80 feet into a rain-swollen creek after pier 3, which partially supported the spans, collapsed. Ninety minutes after the initial collapse, pier 2 and a third span collapsed. Four passenger cart and one tractor-semitrailer plunged into the creek, and 10 persons were fatally injured.

The National Transportation Safety -Board determines that the-probable cause of the collapse of the Schoharie Creek Bridge was the failure of the New York State Thruway Authority to maintain adequate riprap around the bridge piers, which led to severe erosion in the soil beneath the spread footings. Contributing to the accident were ambiguous plans and specifications used for construction of the bridge, an inadequate NYSTA bridge inspection program, and inadequate oversight by the New York State Department of. Transportation and the Federal Highway Administration. Contributing to the severity of the accident was the lack of structural redundancy in the bridge.

The primary safety issues raised by this accident are the adequacy of the bridge design and construction, -the adequacy of the inspection and maintenance practices for this bridge, and the adequacy of the Federal/State oversight of private independent authorities. The report also evaluates-the adequacy of existing Federal Highway Administration/American Association of State Highway and Transportation Officials requirements for underwater inspections of scour.,

Recommendations have been made to the NYSTA, Federal Highway Administration, and the American Association of State Highway and Transportation Officials to correct deficiencies uncovered.