Hazardous Materials Accident Report - Release and Ignition of Hydrogen Following the Collision Between a Tractor/Semitrailer with Horizontally Mounted Cylinders and a Pickup Truck near Ramona, Oklahoma, May 1, 2001

Ramona, Oklahoma
May 1, 2001

NTSB Number: HZM-02-02
NTIS Number: PB2002-917003
Adopted December 10, 2002

Executive Summary

About 2:15 p.m., central daylight time, on May 1, 2001, a northbound tractor, in combination with a semitrailer that had horizontally mounted cylinders filled with compressed hydrogen, which is a flammable gas, struck a northbound pickup truck that had veered in front of the tractor-semitrailer on U.S. Highway 75, 2 miles south of Ramona, Oklahoma. According to witnesses, the tractor-semitrailer then went out of control and overturned while continuing along the highway. It went off the road to the east and traveled 300 more feet before it stopped. During the process, some of the cylinders, valves, piping, and fittings at the rear of the semitrailer were damaged and released hydrogen. The hydrogen ignited and burned the rear of the semitrailer. In the meantime, the pickup truck had also run off the road. The pickup truck's fuel line ruptured, resulting in the truck being destroyed by fire.

As a result of the accident, the truckdriver was killed, and the driver of the pickup truck was seriously injured. Residents of five homes in the vicinity of the accident were asked to evacuate, and the highway was closed for more than 12 hours. Damage, cleanup, and lost revenues were estimated at $155,000.

Probable Cause

The National Transportation Safety Board determines that the probable cause of the May 1, 2001, collision and subsequent fire involving a tractor-semitrailer and a pickup truck in Ramona, Oklahoma, was the failure, for unknown reasons, of the pickup driver to control her vehicle. Contributing to the severity of the accident were the inadequate protection and shielding of the cylinders, valves, piping, and fittings and the inadequate securement of cylinders on the semitrailer.

This report discusses the following safety issues:

  • The adequacy of Federal requirements for protecting cylinders that are horizontally mounted on semitrailers and the valves, piping, and fittings of the cylinders during rollover accidents.
  • The adequacy of the information in the North American Emergency Response Guidebook about compressed hydrogen.

As a result of its investigation of this accident, the Safety Board makes recommendations to the Research and Special Programs Administration.


As a result of its investigation, the National Transportation Safety Board makes the following safety recommendations:

To the Research and Special Programs Administration:

Modify 49 Code of Federal Regulations 173.301 to clearly require that valves, piping, and fittings for cylinders that are horizontally mounted and used to transport hazardous materials are protected from multidirectional forces that are likely to occur during accidents, including rollovers. (H-02-23)

Require that cylinders that transport hazardous materials and are horizontally mounted on a semitrailer be protected from impact with the roadway or terrain to reduce the likelihood of their being fractured and ejected during a rollover accident. (H-02-24)

Revise the information about hydrogen in the North American Emergency Response Guidebook so that it specifically identifies the unique chemical and flammability properties of hydrogen. (H-02-25)