Highway Accident Report

Adopted: June 1, 1972
ON U. S. 90
AUGUST 8, 1971

NTSB Number: HAR-72/03
NTIS Number: PB-211596


At approximately 6:50 p.m., on August 8, 1971, in the northbound lane of U. S. 90, near Gretna, Florida, a tractor van-type semi-trailer combination (hereafter called "truck"), traveling south at 50 m.p.h., collided with an automobile which turned into its path while making a left turn movement preparatory to going east on Florida S.R. 270A.

The impact was sufficient to rotate the automobile and entangle the vehicles together as they skidded forward to the southeast corner of the intersection. After leaving the pavement, the truck struck the embankment of a ditch and rapidly decelerated. During that deceleration, the truck's cargo of steel cylinders containing a methyl bromide 2 percent chlorpicrin mixture, under pressure, shifted forward in the van. The automobile continued along the wall of the ditch embankment and impacted a telephone pole in its path, coming to rest soon thereafter.

As the truck came to rest, steel cylinders hurtled through the front wall of the van and impacted parts of the tractor, the automobile, and each other. Several of the cylinders were punctured and others experienced valve failures, a condition which precipitated the immediate release of high concentrations of the poison chemical mixture into the atmosphere. No fire ensued.
Four of the occupants of the automobile and the truckdriver escaped unaided from the contaminated atmosphere with relatively minor injuries. The four remaining occupants remained in or near the automobile and were exposed for a period of 30 minutes to high concentrations of toxic vapors. They did not survive. Several onsite rescue personnel and bystanders were affected by the contaminated atmosphere, both through inhalation and percutaneous absorption. In all, there were four fatalities and 14 injured. The cause of deaths in this accident has been directly attributed to exposure to the spilled cargo. No autopsies were requested by local authorities, nor were any conducted.

Rescue response was delayed because of tardiness in accident notification. No first aid was administered at the accident scene, nor were the victims removed from the contaminated atmosphere until after the arrival of the first ambulance, some 25 minutes after the collision.

The National Transportation Safety Board determines that the cause of this accident was the passing maneuver of the truckdriver who approached a recognizable intersection on the wrong side of a solid yellow centerline and the execution, without signaling, of a left turn by the automobile driver into the path of the overtaking truck. The probable cause of the fatalities in this accident was the prolonged exposure of the disabled occupants of the automobile to high concentrations of the poison chemical mixture which escaped from shifted and damaged containers.

Contributing to the severity of the losses was the failure of the carrier to comply with the Motor Carrier Safety Regulations which call for the securing of cargo against load shift in the event of an accident; the pressurization of the cargo containers; the stiff, hot, humid atmospheric conditions; the "fail-open" cylinder valve configuration; and delay in the removal of the disabled victims from the contaminated atmosphere.


The National Transportation Safety Board directed recommendations relating to this accident to the Secretary of Transportation on November 11, 197 1, and April 27, 1972; copies are included as Appendix F.

The Safety Board further recommends that:

1. The Bureau of Motor Carrier Safety, Federal Highway Administration, develop and implement a program through which a statistical base can be accumulated for engineering design and crashworthiness criteria for container cargo securement, cargo containment within the vehicle, and other hazard controls associated with vehicle acceleration and decelerations under accident conditions.

2. The Hazardous Materials Regulations Board (HMRB) of the Department of Transportation initiate rulemaking which would:

(a) require manufacturers to submit to HMRB the hazard control measures utilized in the manufacture of hazardous materials.

(b) compare the hazard control measures utilized in manufacture with those required for transportation of hazardous materials; and

(c) take into consideration applicable hazard control measures resulting from these comparisons in the formulation of regulation's for the transportation of hazardous materials. The comparison should be placed in the public docket of rulemaking proceedings.

3. The Hazardous Materials Regulation Board of the Department of Transportation expeditiously act to bring about the development and implementation of "fail-closed" shut-off valves for containers used for transportation of liquefied hazardous materials under pressure to improve the crashworthiness of such containers in transportation accidents.