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Accident Report Detail

Student Transportation Lines, Inc., Charter Bus Climbing of Bridge Rail and Overturn

Executive Summary

‚ÄčAt 10:55 a.m. on May 21, 1976, a charter bus carrying 52 persons struck and mounted a section of the bridge rail system on the Marina Vista offramp of I-680 near Martinez, California. The bus rolled off the top of the curved bridge rail and landed on its roof. Twenty-nine of the occupants died and the rest sustained minor to serious injuries.

Probable Cause

‚ÄčThe National Transportation Safety Board determines that the probable cause of this accident was the failure of the driver, who was unfamiliar with the bus, to correctly monitor the service brake air pressure gauge, recognize the loss of air, and take appropriate action including application of the emergency airbrake.

Contributing to the accident were: (1) the failure of the air compressor drivebelt, (2) the failure of the maintenance program and pretrip inspection to detect and replace the deteriorated air compressor drivebelt, (3) the failure of the signing system to adequately alert the driver to the critical geometrics of the ramp, (4) the severe radius of the curvature of the ramp, (5) the design of the curb as part of the ramp railing, and (6) a bridge rail system that did not redirect the bus.

Accident Location: Martinez , CA    
Accident Date: 5/21/1976
Accident ID: 79640

Date Adopted: 9/29/1977
NTSB Number: HAR-77-02
NTIS Number: PB-275193/AS

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