HAZARDOUS MATERIALS ACCIDENT REPORT
Adopted: September 4, 1991
OVERTURN OF A TRACTOR-SEMITRAILER
(CARGO TANK) WITH THE RELEASE OF
AUTOMOTIVE GASOLINE AND FIRE
CARMICHAEL, CALIFORNIA
FEBRUARY 13, 1991 
NTSB Number: HZM-91/01
NTIS Number: PB91-917004
SYNOPSIS
About 3 a.m. Pacific standard time on February 13, 1991, a tractor-semitrailer (cargo tank) overturned as the vehicle was traveling on a main urban roadway in Carmichael, California. The tractor and semitrailer were owned and operated by Calzona Tankways, Inc., of Phoenix, Arizona. At the time of the accident, the truck was being used for the intrastate delivery of gasoline to service stations; the cargo tank contained about 8,800 gallons of automotive gasoline.

The driver lost control of the vehicle in a curve. The vehicle overturned onto its side and struck the embankment of a drainage ditch located in a dirt field beside the road. The cargo tank bounced and came to rest in the dirt field and adjacent to the drainage ditch. The rear end of the cargo tank landed on an unoccupied car parked in the field.

Gasoline from the cargo tank spilled into the drainage ditch, which extended under the roadway and behind private residences nearby. About 15 minutes after the overturn, the gasoline ignited behind a residence. The fire flashed back and engulfed the overturned cargo tank, and the car under the cargo tank. A second unoccupied car parked near the overturned tank truck also caught fire. Gasoline runoff in the drainage ditch entered the underground drainage system and was also ignited.
In addition to the total loss of the tank truck, its cargo, and the two parked cars, four homes and their contents were destroyed or heavily damaged by fire, and the residents from a 2-mile-square area were evacuated. Total property damage and cleanup costs were estimated at nearly $1 million. There were three minor injuries.

The National Transportation Safety Board determines that the probable cause of the accident was the inattention of the driver, for undetermined reasons, which resulted in his operation of the tank truck at excessive speeds leading to its overturn. Contributing to the severity of the accident was the failure of one of the liquid-level sensors mounted on the manhole cover for the forward compartment of the cargo tank to remain secured.

The following safety issues are discussed in this report:

1. The lack of U.S. Department of Transportation performance standards for components mounted on manhole covers on motor vehicle tanks transporting bulk hazardous liquids;

2. The adequacy of California standards for highway bulk liquid cargo tanks;

3. The effectiveness of the carrier's evaluation of driver training and performance; and

4. The lack of requirements for postaccident toxicological testing of drivers involved in the intrastate transportation of hazardous materials.

Safety recommendations concerning these issues were made to the Research and Special Programs Administration, the Federal Highway Administration, and the National Highway Traffic Safety Administration of the U.S. Department of Transportation; to the State of California; to the other States and U.S. Territories; and to the motor vehicle carrier.

RECOMMENDATIONS

to the Federal Highway Administration, U.S. Department of Transportation:

Require postaccident toxicological testing for alcohol and drug impairment of commercial vehicle operators involved with the intrastate transportation of hazardous materials in bulk. (Class II, Priority Action) (H-91-32)

Issue periodic “On-Guard” bulletins to remind all carriers and drivers to be attentive and aware of the conditions that can lead to a loss of stability and rollover in a tank truck. (Class II, Priority Action) (H-91-33)

to the Research and Special Programs Administration, U.S. Department of Transportation:

Require that all fittings and devices mounted on a manhole cover of cargo tanks meet the same performance standard to withstand the static internal fluid pressure as that required for the manhole cover. (Class III, Longer Term Action) (H-91-34)

to the National Highway Traffic Safety Administration, U.S. Department of Transportation:

Proceed with and complete the research of human performance factors that may reduce rollovers in heavy trucks (tractor-semitrailer combinations) as recommended in the 1987 Heavy Truck Safety Study prepared in response to Section 216 of Public Law 98-554. (Class III, Longer Term Action) (H-91-35)

to the State of California:

Adopt design standards for highway bulk liquid cargo tanks that are at least equivalent to current Federal standards in 49 CFR Part 171 through 180. (Class II, Priority Action) (H-91-36)

to the 50 States, the District of Columbia, the Commonwealth of Puerto Rico, the Virgin Islands, and U.S. Territories:

Require postaccident toxicological testing for alcohol and drug impairment of commercial vehicle operators involved with the intrastate transportation of hazardous materials in bulk. (Class II, Priority Action) (H-91-37)

to Calzona Tankways, Inc.:

Provide regular reminders to company drivers about the loss of stability and rollover through safety meetings, and the periodic flyers and letters sent to the drivers. (Class II, Priority Action) (H-91-38)