Highway Accident Report

Adopted: September 29, 1977
MAY 21, 1976

NTSB Number: HAR-77/02
NTIS Number: PB-275193/AS


At 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.

The 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.


As a result of its investigation of this accident the National Transportation Safety Board made the following recommendations:

to the California Department of Transportation:

"Erect at the approach to the Marina Vista offramp an exit sign that incorporates a diagram of the curvature of the ramp to illustrate its severity and relocate or supplement the advisory exit speed sign to improve its warning to approaching drivers. (Class I, Urgent Followup) (H-77-16)"

to the California Highway Patrol:

"Initiate a program that will insure the availability of information about carrier terminal ratings and their meanings to all users of charter-party and schoolbus carriers' services. (Class II, Priority Followup) (H-77-17)

"Modify the enforcement policy set forth in its Motor Vehicle Safety Operations Program to provide for letters of warning and/or the initiation of charges against those carriers/terminals upon the receipt of a second consecutive "C" rating. (Class II, Priority Followup) (H-77-18)

"Modify its Motor Carrier Safety Operations Program to require that each carrier is held responsible to insure that all drivers-both new and experienced-are properly tested and examined to assure their driving capability and that such drivers are thoroughly familiar with all of the operational functions and controls of each vehicle they drive. (Class II, Priority Followup) (H-77-19)"

to the Federal Highway Administration:

"Prepare and issue an advisory document citing the proper techniques for inspecting air compressor drivebelts. The bulletin should be disseminated widely throughout the commercial motor carrier industries and to all agencies charged with the regulation of intrastate motor carrier safety. (Class II, Priority Followup) (H-77-11)

"Develop bridge railing designs that will meet performance standards to be established by FHWA for various classes of vehicles and that will be sufficient in number to meet the various State requirements with regard to climatic and other physical conditions that affect the operation and maintenance of a roadway system. Such bridge barrier railing designs should be available to States that do not desire to develop their own designs in accordance with mandatory performance standards issued by FHWA. (Class II, Priority Followup) (H-77-12)

"Investigate through dynamic crashtesting and analytical procedures the effects of various geometric configurations and adjacent roadway surfaces on the performance of traffic barrier rail systems. The investigation should also consider how maintenance practices or the lack of maintenance affects the performance of the barrier rail systems. (Class II, Priority Followup) (H-77-13)

"In cooperation with the States, establish priority guidelines for improving, through modification or retrofit, the performance of existing traffic barrier rail systems at bridges. Consideration should be given in the priority guidelines to the potential for multi-fatality accidents involving high occupancy vehicles such as buses. (Class II, Priority Followup) (H-77-14)

"In cooperation with the States, determine if the current design and placement of guide, directional, advisory, and warning signs, and other necessary traffic control devices on highway exit ramps are adequate to provide a driver with understandable and performance-related information necessary for the selection and safe negotiation of the desired ramp. The results of the investigation should be used to improve the criteria contained in the Manual on Uniform Traffic Control Devices. (Class II, Priority Followup) (H-77-15)"