Repeated failures of Edmonton's Metro LRT Line signalling system raise safety questions
Trains again running at reduced speed after crossing gate inexplicably lifted
The safety of the problem-plagued Metro LRT Line is being questioned after an incident Monday in which the signalling system failed and the crossing gate inexplicably lifted as a train was about to cross a busy intersection near the Northern Alberta Institute of Technology.
A CBC News investigation has found this latest incident was one of at least two signalling failures since the line reached full speed earlier this year. The other incident occurred in July.
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In the incident Monday, as the train prepared to cross the Princess Elizabeth Avenue intersection at about 6:07 a.m., the crossing gate raised prematurely. The train's signalling system communicated, as it was designed to do, with the line's signalling system and automatically applied its emergency braking system. There were no injuries.
But that sort of "very serious" failure should never happen, especially in a system that is already fully operational, said a source with direct knowledge of the incident, who spoke to CBC News on condition of anonymity.
"These crossing warning systems are supposed to be what we class as vital and fail-safe," said the source, an expert in rail operations.
"So if they do fail in any kind of manner, what is supposed to happen is that the gates come down, because that is the most safe position for the train crossing through the intersection. And that is how you design these signalling systems to be fail-safe."
The city did not inform the public about the system failure. In an email to CBC News Thursday, spokesperson Holly Budd said Edmonton Transit Service (ETS) does not "generally publicize operator instructions when the impact to transit service is minimal."
Fail-safe mode activated
In an interview Friday, Eddie Robar, the city's head of transit, confirmed the incidents but downplayed their seriousness.
Robar said that when Monday's incident occurred, the train was only running at about 16 km/h when the automatic braking system engaged before the train entered the intersection. He said the gates then lowered, the driver phoned in the problem to the control system, the system was reset, and the train continued on.
Robar did not know the exact date of the incident in July. But he said the gate did not lower when it should have as the train exited the Kingsway station.
The driver saw this, manually applied the brakes and slowed the train until the gates were in place before passing through the intersection. The trains operated at a reduced speed until the software issue had been fixed.
"Part of what we are looking at is that technical link between train, gates and signals," Robar said of the most recent incident. "So in this case, there was a failure on that part, but the safety activation of the system itself was intact."
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The fact that the fail-safe mode activated in the most recent incident was a "perfect example of the safety of the line itself," Robar said, adding later that, "if it wasn't safe to operate, then I wouldn't be operating the train."
But Robar doesn't know why the crossing gate raised prematurely. They are now trying to pinpoint the problem, and until they do, the speed restriction on the Metro Line will remain in place, just as it was in July.
Robar said the city didn't notify the public about these incidents because it didn't affect service.
Trains running at reduced speed
After CBC News contacted the city on Thursday, its integrated infrastructure services department sent a memo to councillors and senior officials, a copy of which has been obtained by CBC News. The department sent the memo 15 minutes before it provided an emailed statement to CBC News.
The memo said ETS has ordered all drivers to lower their speed along the line "until the issue is resolved." In her email to CBC News, Budd said the slower speed would not affect the train's schedule.
"Operating a safe and efficient LRT system is the City of Edmonton's top priority when it comes to operating the LRT system," the memo continued.
The internal memo cited the city's ongoing struggles with Thales, its signal contractor, but stressed that "these deficiencies are quality issues, not safety issues." It said Thales is investigating the problem.
"That's really underplaying the concern," the source said, alluding to "the fact that there have been multiple safety-related failures of the system."
City contradicts itself
In fact, the city itself has called this type of failure a safety issue. In May 2016, deputy city manager Adam Laughlin said serious safety issues, such as incidents in which traffic arms did not lower as trains approached intersections, were preventing the city from approving Metro LRT trains to run at full speed.
The internal memo to city councillors made no reference to the previous safety incident. The source, who also had direct knowledge of the July incident, said in that case the crossing gate did not lower in time. The driver manually applied the brakes.
The source characterized the incident at the crossing near NAIT on Monday as being "an unsafe failure mode."
The Metro LRT line has been plagued for years by setbacks and signalling problems.
For nearly a year and half after the line opened in September 2015, trains only ran at half speed due to safety issues the city has alleged were caused by Thales' signalling software. In February 2017, the trains were finally allowed to run at full speed. But with this latest signalling failure, the speed has been reduced again.
The source said that given the multiple failures, the Metro Line should not be running with its current signalling system.
"We should never be getting these type of failures, and this many failures, with supposedly a valid safety case."
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