NTSB Probes Rollovers by Hazmat Tanker Trucks

Firefighters secure the scene of an accident after a liquid propane tanker exploded on an Indianapolis highway ramp on Thursday, Oct. 22, 2009.
AP/Michelle Pemberton, Star
A tanker truck hauling propane ran off a busy interstate in Indianapolis, struck a guardrail and exploded last October. The giant fireball could be seen miles away.

The accident has prompted the National Transportation Safety Board to examine whether enough is being done to prevent tanker trucks hauling hazardous loads from rolling over. Tankers, more than other trucks, are susceptible to rollovers because the weight distribution of the liquid they carry can shift suddenly if vehicle changes direction too quickly.

A two-day hearing on the fiery crash begins Tuesday.

The truck's tractor separated from the tanker trailer and slammed into a bridge abutment. The impact tore a pillar away, but fortunately the bridge didn't come down. One driver, unable to stop when suddenly confronted with a wall of flame, put her foot to the floor and sped through it. The heat melted the fenders off her car, but she and her two passengers survived. Five people were injured, but no one was killed.

Loads are dispatched on tanker trucks more than 100,000 times a day in the U.S. There are, on average, 1,265 cargo tanker rollovers annually.

The safety board wants to know whether electronic stability systems similar to those required for cars would prevent tanker rollovers. The sensors tell the vehicle's onboard computer when weight is shifting or is about to shift. The computer automatically applies brakes to one or more wheels to compensate until balance is restored.

All new cars are required to have the systems, but not trucks - even though trucks represent a disproportionate share of rollover accidents, said Henry Jasny, general counsel for Advocates for Highway and Auto Safety.

"This technology is somewhat more expensive," Jasny said, "but that it wouldn't be required for trucks when they are so over-represented in crashes doesn't make sense to us."

John Conley, president of National Tank Truck Carriers, which represents the tanker truck operators, said most new tanker trailers have the rollover prevention equipment even though it's not required. However, he said new tractor trucks that pull the tankers don't necessarily have the equipment.

And, he said, retrofitting older tractor trucks and tanker trailers isn't practical.

The electronic stability systems work best at preventing tanker trucks driving too fast on highway exit or entry ramps from rolling over as they round a curve, Conley said. But they're less effective at preventing rollovers involving trucks already on the interstate, he said.

"They are not a silver bullet," Conley said.

For more info:
NTSB Hearing on Truck-Tractor/Cargo Tank Semitrailer Rollovers
By Associated Press Writer Joan Lowy