The first generation of the OC Transpo double-decker performed so poorly during the winter tests in 2007 that the driver considered it unsafe to continue.
The surprising conclusion is hidden in a 189-page report by the National Research Council, while the city assessed the suitability of UK-made buses in cold climates. Over time, OC Transpo bought 133 of the $ 1 million buses, now subject to scrutiny following a second disastrous crash last week.
"This bus has not yet been deployed in an area of winter weather in North America such as Ottawa, so it was interesting to assess its performance in winter," the introduction says.
Enviro 500, manufactured by Alexander Dennis Ltd., was shipped to a well-known test runway in Blainville, Virginia, and equipped with sandbags to simulate an actual passenger load.
Among the standard tests in the bus industry is a so-called "double-lane change" in which the bus is bound to start in the right lane, move intelligently to the left and, about 35 meters later, return to the right. (Imagine passing a car and then back to the curb track.) The test was done 26 times at different speeds, with posts marking the tracks, on a snow-covered track with stretches of ice below.
The faster the bus moved, the worse the results. At 35 kilometers per hour, the bus made five clean runs on the double track, no problem. At 40 km / h, the bus had only two clean ones of five, striking a cone in the other three attempts.
When the test speed was increased to 50 km / h, things began to collapse on that January day, when the temperature was -20 ° C. The bus entered the course at 47 km / h, the report said.
"The driver said he was not safe at this speed, he hit cones, he broke the steering wheel sensor, he had to get wide out of the way to recover."
Later, on the same page, the authors write: "The driver managed to stop the bus safely. However, he expressed his concern to try another maneuver at the same speed and it was decided that no other test would be performed. "
OC Transpo general manager John Manconi emphasized that today's buses are safe vehicles in the winter.
He said the NRC recommended in 2007 that rear-wheel-assist and electronic braking systems be added as options for vehicles and that OC Transpo has always added these features in bulk purchases in 2012, 2015 and 2017.
"We went the extra mile. I do not want the community to panic about these things. "
The NRC said these additional features would be a "significant improvement" on slippery surfaces.
There is no mention in the NRC report that speed limits on the Transitway range from 50 km / h through stations of more than 50 to 90 km / h in straight and clear stretches.
But the testers issued a warning.
"Based on the test results, a bus driver should have no difficulty performing a double-lane change on a similar surface when the entry speed is less than 46 km / h. This is below the 60 km / h speed limit of a typical urban arterial road and well below the Queensway 100 km / h speed limit.
"It is unlikely that a driver will be able to make an evasive double-lane change maneuver successful under conditions similar to those of those tests at the speeds prevailing on those highways. This maneuver would be even more difficult if temperatures were around zero, when snow and ice would have been much more slippery. "
Interestingly, the authors of the C.V. Tabra and J.D. Patten study did not discourage the city of Ottawa from buying the buses, nor was there a recognition that – daily – double-decker buses would obviously make track changes at speeds exceeding 46 km / h.
"Based on the assessment (NRC) of the Enviro 500 two-story shuttle in winter conditions, the performance of the bus on snow-covered surfaces should not be a factor of concern in the city's decision regarding future bus purchase plans. "
None of the investigators could be found on Thursday. It is unknown what role, if any, change of track, braking skills or snow conditions snow played in the tragedy on Friday, which took three lives and left 23 injured.
Manconi has repeatedly said that buses meet all the technical standards set by the federal agencies and are used safely around the world. Their assurance, however, does not mention that the Independent Transportation Safety Board declares that two-story buses are not built for any collision impact pattern because they do not exist in Canada.
This is especially true for the second deck where most of the deaths occurred in the two catastrophic crashes that killed nine people in 2013 and 2019. The buses, which are 14 feet high, also have (on rare occasions) actually been blown right off the road in high winds.
The NRC study also looked at the braking capacity of the bus. He found the bus braked well under snowy conditions.
"The bus followed a straight path under braking without showing any tendency to leave. Some steering corrections were sometimes necessary due to the uneven snow-covered tracks on which the tests were run. "
After a two-year pilot, OC Transpo put its first double decker on regular service in 2012.
To contact Kelly Egan, call 613-726-5896 or email [email protected]
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