May 11 marks the 44th anniversary of one of the scariest moments in Houston history, when a semitrailer carrying more than 7,000 gallons of anhydrous ammonia fell from a freeway ramp, spilling its lethal contents.
The incident, which left seven dead and nearly 200 injured, caused officials to rethink how to tackle chemical disasters and led to rules still in use today.
Over forty years later, the route that ammonia truck took still snakes through a city that has doubled in size, leaving Houston vulnerable to a catastrophic accident.
Just after 11 a.m. on May 11, 1976, a tanker truck carrying the dangerous chemical fell onto the Southwest Freeway from the 610 West Loop above. The driver had lost control of the rig and hit a support beam.
The National Transportation Safety Board would later determine that the driver was not traveling at a safe speed. He barely missed landing on a car passing by. Not much was left from the truck in the aftermath.
From a Houston Post dateline: “As the sign says, the weather is fair, it’s 83 degrees and the time is 11:17 a.m. The date is also May 11, and that white cloud in the distance is the toxic blanket of anhydrous ammonia fumes which resulted from a tank truck crash at Southwest Freeway and the West Loop which killed five persons. The Texas Air Control Board took the picture from its offices at 5555 West Loop South.”
This photo shows the ammonia truck’s chassis and vehicle parts being hauled away after the fatal accident and chemical spill.
Ammonia, its 7,000-gallon load, was not the standard cleaning product one would use at home. This was pure, undiluted industrial anhydrous ammonia that is used in heavy-duty chemical processes and is extremely deadly if mishandled.
The fumes that were released proved fatal for those who were too close. Freeway traffic was closed for three miles in all directions. Most nearby residents left their homes. Those who were close enough to detect the smell were told to relocate until the odor dissipated.
A recording of the KPRC-AM coverage of the event can be heard here. Reporter Bob Raleigh spoke to witnesses who saw the accident and confirmed fatalities at the scene with fire officials. It’s a 40-minute time capsule from one of the worst disasters in Houston history up to that point.
KTRK-TV reports from the scene show medics taking away burn victims and everyday Houstonians chipping in to help the recovery effort. One medic said he had 12 people in one ambulance. Area hospitals and emergency rooms were inundated.
There was almost no chance of survival for those caught in a cloud of ammonia that strong, and most greenery in the area later died.
Pictures from the Houston Post’s archive are surreal. The news would make it around the world.
