TORONTO - An allegedly defective guardrail widely used across Canada and the U.S. has passed a series of crash tests, U.S. authorities said Friday, but the findings are unlikely to end concerns about their safety.

Questions about Trinity's ET Plus unit continued to swirl as highway officials conceded results of one of the tests involving a small passenger car could be interpreted differently.

"Based on our analysis of the crash test results and the analysis we conducted into the level of risk of serious injuries, we concluded...the ET Plus end terminal meets the applicable crash test criteria," Tony Furst, associate administrator for safety for the Federal Highway Administration, told a news teleconference.

"There was no penetration of the vehicle by any test article in any of the four tests."

U.S. highway authorities ordered the crash tests on the ET Plus — subject of a recent $500-million proposed Canadian class action — after an American jury found Texas-based Trinity Industries guilty last year of fraud in a civil action.

Trinity had modified the guardrail unit about 10 years ago without notifying appropriate authorities and critics say the ET Plus end unit can end up impaling occupants of a vehicle like a "spear" rather than protecting them.

Most states and several provinces, including Quebec, Nova Scotia, Alberta and New Brunswick, have stopped installing them pending the testing and analysis but thousands remain in place on the country's highways.

Greg Nadeau, deputy administrator of the Federal Highway Administration, said the agency was making no recommendations on whether installation of the units should resume, saying that decision is up to local authorities.

In the last of the eight crash tests done in Texas, a small passenger car slammed into the rail at about 100 kilometres an hour.

Furst said it was "unlikely" a driver exposed to the crash conditions would have been at risk of serious injury from the folded rail impact to the driver side door.

"We are mindful that others have reached their own conclusions," Furst said.

Lawyer Matt Baer, who launched the proposed class action on behalf of Stratford, Ont., said the administration considered the test a pass because the guardrail did not penetrate the door.

Still, he said, the test casts doubt on the safety of the rails.

"The guardrail did lock up in the feeder chute and at the head which is a classic failure in real-world accidents," Baer said.

"It is worrisome both that they were so close to failure in a test designed to pass under perfect conditions."

Zyg Gorski, an accident-reconstruction expert based in London, Ont., said the problem with the U.S. tests is that they occur under controlled conditions that don't necessarily replicate reality.

One example, he said, is that gravel thrown into the rail channels from snowplows could cause them to jam in a crash.

"No one is taking real-life collisions and examining what is happening" Gorski said. "That's frightening."

A spokesman for Trinity said the ET Plus has now been "successfully crash tested more times than any product of its kind."

News from © The Canadian Press, 2015