The 1976 Houston Ammonia Truck Disaster Listed as the Worst in Houston’s History

Dallas, 06/23/2016 /SubmitPressRelease123/

At approximately 11 o’clock in the morning on a bright sunny day, drivers at the interchange of the Southwest Freeway and the 610 West Loop became the victims of the worst truck disaster in Houston’s history.

Texas leading truck accident lawyer Attorney Amy Witherite reviews The 1976 Houston Ammonia Truck Disaster.


On this date, a commercial tanker driven by William Gregory Schmidt, 28, carrying over 7,000 gallons of pressurized anhydrous ammonia crashed into and through the barrier, falling down onto the freeway below. The ensuing release of ammonia gas resulted in the death of six others besides the driver of the truck. This horrific accident also led to a number of changes in laws regarding the construction of tanker trailers as well as speed limits for chemical haulers, and the construction of barricades.


Source ABC News Channel 13 KTRK: “The Worst Accident in Houston History: The 1976 Ammonia Truck Disaster”


” HOUSTON (KTRK) — It was the worst accident in Houston history. On May 11, 1976, at 11:08 in the morning, a tank truck carrying 7500 gallons of anhydrous ammonia lost control, crashed through a guardrail and careened off a ramp to the freeway below.”


To read the report, visit:


The Scariest Moment in Houston’s History


This accident is considered to be one of the “scariest” moments in the city’s long history. By the time it was all over, a total of six people died either at the scene or in nearby hospitals. However, there was one more fatality three years later. This was Karen Bijak, 27, a former beauty queen who would die in 1979 from health complications as a result of exposure to the fumes.


Along with the seven fatalities, another 178 people were injured as a result of ammonia fume inhalation and direct contact with the fumes.  Of these, 78 were deemed critical and admitted to the hospital for extended treatments, the other 100 were treated and released.


How the Accident Unfolded


According to witnesses, the truck driven by Schmidt appeared to hit the barrier on the overpass and then proceeded to topple over it. The truck and trailer then plummeted onto the freeway below, slamming into one of the support columns. The trailer broke into two sections, releasing a huge cloud of ammonia vapor that could be seen from miles away.


The victims in cars who were engulfed by the fumes were overcome, causing some to crash. All fatalities were listed as a direct result of ammonia fume inhalation. Many managed to move far enough away from the scene that they were able to get clear of the cloud, others were not so lucky, including one man who tried to duck into a culvert to find fresh air only to be completely overwhelmed by the fumes.

Other victims also included the many motorists who stopped their own vehicles and attempted to aid those who were already overcome by fumes, several members of the emergency response teams, and several members of the press covering the accident.


What the NTSB Investigation Found


Anytime there is an accident of this magnitude, the NTSB (National Traffic Safety Board) conducts an investigation in an effort to determine the cause. Since the driver of the tractor-trailer combination died at the time of the accident, the investigators had to rely on eyewitness reports and evidence gathered from the scene.


The driver of an automobile in front of the truck driven by Schmidt stated that she noticed it was following her at several car length’s distance. She noted that her speedometer indicated she was traveling at 59 mph and that she accelerated to 70 mph in order to facilitate a lane change to the right, but the truck kept up with her pace.


Both vehicles exited from I-610 onto the connector ramp that would take them to the Southwest Freeway.  The driver stated she exited to the right while the truck exited to the left. At the time, the driver of the car stated she was driving at approximately 40 to 45 mph and that the truck appeared to be going approximately 55 to 60 mph.


As the truck proceeded into the curve and out onto the bridge, it appeared to roll and strike the curb. The tractor-trailer then struck the concrete and steel tubing of the barrier and kept going, breaking through both with ease. It then plunged off the overpass and fell approximately 15 feet onto the freeway below. At this point the combination also struck one of the support pillars for the overpass seriously damaging it.


Source NTSB Highway Accident Report NTSB – HAR-77-1


About 11.08 a.m., on May 11, 1976, a Transport Company of Texas tractor-semi trailer (tank) transporting 7,509 gallons of anhydrous ammonia struck and penetrated a bridge rail on a ramp connecting I-610 with the Southwest Freeway (U.S. 59) in Houston, Texas.


To read the entire report, visit: ttp://



High Number of Injuries


At the point of impact, the sudden release of the pressurized anhydrous ammonia (an industrial strength cleaning agent) created what can only be described as an explosion that destroyed the tractor and trailer. A total of twelve vehicles in the immediate vicinity of the accident were damaged by flying debris, of these four were subjected to severe damage.


Injuries to Persons

















Courtesy NTSB – HAR-77-1


All injuries with the exception of the driver of the truck were caused by the release of the ammonia gas as a result of the accident. According to the records, there were approximately 500 people located within a 1/4-mile radius of the accident at the time.


Cause of the Accident Determined


The NTSB investigation determined that several factors came into play related directly to the cause of the accident. The transmission of the truck was found to be in ninth gear helping to corroborate the testimony of the driver who stated she thought that it was traveling between 55 and 60 mph. While the right-hand side of the exit ramp had a posted warning sign indicating a maximum recommended exit speed of 40 mph, the left side was not posted.


However, all information garnered from the truck, including a pyrometer needle stuck in the “red range” indicated the truck was most likely traveling at 5.36 mph, too fast for the truck to safely negotiate the curve with less than a full tank. The tank was only filled to 71.8 percent of its total capacity. This led investigators to believe that the lateral surge of the load, which occurred when the truck struck the curb, caused the truck and trailer to begin overturning. Once in motion, the truck could not be stopped and it continued through the barrier and onto the freeway below.  


Finally, the NTSB report noted that the guardrail system in use on this section of the overpass was “of an outdated design” and was only intended to prevent automobiles from being able to penetrate it. Thus, instead of redirecting the truck back out onto the road, stopping it from penetrating the guardrail, the truck crashed through the barricade and onto the freeway below.  


Recommendations that Resulted from these Findings


The NTSB sent a recommendation to the Federal Highway Administration (Bureau of Motor Carrier Safety) that they should carefully investigate the problem of overturn stability that can result from the surge of liquid cargoes in all partially loaded tractor-trailer combinations.  The idea behind this being to find ways via Federal regulation to design tank trailers in such a manner as to reduce or eliminate the effects of the liquid surge.


At the same time, a recommendation was sent to the Department of Transportation that they initiate research into ways to reduce the risks of injury and damage resulting from this type of accident.


Changes and New Laws


Accidents such as this one have led to many changes in the law designed to protect the general public from these types of accidents and to reduce the amount of collateral damage. Among the changes are new tank trailer designs that include partitions and/or baffles designed to reduce or eliminate the type of liquid surge that contributed heavily to the overturning of the tractor-trailer combination.


Changes in the design of overpass guardrails and the materials used to build them have also been instituted. These new designs must be able to redirect the full weight of all vehicles, including tractor-trailers, back onto the road instead of allowing them to penetrate and tumble onto the road below.


If both of these recommendations had already been in place prior to this horrific accident in May of 1976, the number of injuries and fatalities would likely have been significantly lessened, if not completely eliminated. Since the accident, barriers and guardrails across the country have been updated and improved to significantly to reduce the possibility that buses and commercial trucks, including those weighing up to 80,000 pounds, will penetrate them resulting in similar situations.


Finally, as proof that these changes to the laws have been effective, a similar accident occurred on June 4, 2013. In this particular accident, occurring at the same location, a truck loaded with methanol crashed into the barrier but was directed back away from the barrier. While it took many hours for the Hazmat teams to clean the mess up, there were no significant injuries.


Laws now exist designed to allow victims to seek recovery of damages in the event they are involved in an accident in which the truck driver is found to have acted in a negligent manner resulting in physical harm.


If you would like help with a Texas 18-wheeler accident that has resulted in physical harm, contact the law offices of Texas 18-wheeler accident Lawyers of Eberstein Whitherite LLP by calling 1-800 Truck Wreck (1-800-878-2597) any time of day or night.


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