As crash investigators probe the devastating collision of an Ottawa transit bus into a Via Rail train to determine what happened, there’s one key source they may not be able to count on: the data recorded by the bus.

Transport Canada requires trains to use a device to record crash data, but the same is not true for buses, which transport a couple of billion passengers across Canada every year.

Investigators from the Transportation Safety Board (TSB) began examining the site of the crash half an hour after it happened Wednesday at the tail end of morning rush hour. They will spend months looking at why the bus failed to stop, despite the lowered crossing gate at Fallowfield Road.

“We are trying to understand all of the factors that go along with that,” lead TSB investigator Robert Johnston told CBC News on Thursday.

Eyewitness reports of the last moments vary, with some saying the bus did not seem to slow while others state the driver seemed to try to hit the brakes twice but couldn’t stop in time.

As investigators seek to answer questions about the crash, one of the major sources of crash information will be whatever was recorded on both the vehicles.

Retrieval of the so-called black box or data event recorder from the Via Rail happened late Monday and the device is currently headed to Montreal to be downloaded, said Johnston.

But obtaining event data from the double-decker bus could pose a bigger challenge.

One of the key elements holding clues for investigators will be the engine's data recorder.

“Generally, that’s where we look first,” said Jonathan Lawrence, a forensic engineer at B.C.-based MEA Forensic, a private firm that probes crashes involved in legal cases. “Most modern truck and bus engines will have a little computer on the side of them that’s monitoring what’s going on and most of them will capture some kind of information.”

Bus vs. train crash graphic

Though the engine devices can record a wealth of data, what they record and how they are programmed varies by manufacturer and even by model.

“It’s not like on a locomotive where a locomotive event recorder captures specific data and we know what to look for,” said Johnston. “It comes in different forms and captures different information. At this point, we are just trying to see what we have before we can make any other determination.”

Beyond that, some manufacturers give purchasers, like OC Transpo, the decision of whether or not to enable the engine’s data recording and the parameters of what it will record.

The engine control module can include information such as the speed the vehicle was travelling for the last minute before the crash, whether there was aggressive braking, plus details about throttle and clutch use. It can shed light on how a driver responded in the moments before a crash.

Blink of an eye

OC Transpo did not return CBC calls requesting information on its engine recording capabilities and whether recording was even turned on. Alexander Dennis, the U.K. company that manufactures the Enviro500 double-decker bus purchased by the city, offers different engine specifications.

At a press conference, John Manconi, general manager of Ottawa’s Transit Services, stated that the bus had GPS and would turn over any recording devices that are “required by the investigative agencies,” but did not state what recording devices are on the bus.

GPS-based systems give fleet owners a way to track vehicles in real time, but their worth for crash investigators is limited.

“When we get into crash mode, that’s a different situation because crashes happen typically in the order of 100 to 150 milliseconds, in about the time you blink your eye,” said Dr. Robert McElroy, a U.S. transportation safety advocate and accident reconstructionist.

Neither Canada nor the United States regulate data event recording by commercial buses and trucks, though there have been calls for years across the continent.

Safety advocates and traffic accident experts say that it’s time to require buses and large trucks to record crash data in a standardized way.

“I personally think that every vehicle on the road should have a data collector because it will do nothing but improve highway safety,” said Terry Lolacher, president of the Canadian Association of Technical Accident Investigators and Reconstructionists.

“It’s certainly a piece of the puzzle that would assist in figuring out why things happened,” said Lolacher. “And if we analyze things so we understand why they happen, we can put things in place to prevent them from happening again.”

More questions than answers

Despite the lack of requirements around bus use of data event recorders, last September the U.S. began requiring all new cars and small trucks to standardize their data event recorders to make them collect information in the same way and in an accessible format.

The change was in part prompted by the Toyota unintended-acceleration issue and discovery that only one computer could read the data from the recorders.

McElroy said now is the time to standardize crash recording in buses as well.

“[The Ottawa accident] probably represents an alert call for North America to assess the requirement and implementation for a standard for buses in North America,” said McElroy.

McElroy said standardization in crash recorders in buses and trucks would not only save time for crash investigators but potentially give them more information.

“We need one box that would represent a central location that would record basically the same things that we would see in a car: which is going to represent how fast it was going, whether it was slowing down, is the vehicle attempting a turning manoeuvre left or right, gear selection, interlock brakes,” said McElroy.

Video and audio recording devices can also provide essential information, such as when the driver or passengers became aware of a danger, he notes.

Currently, companies can buy special data event recorders to add to their vehicles, but few go that expensive route outside private companies seeking to monitor driver behaviour.

In the U.S., some companies also outfit their fleets with video cameras recording the interior or exterior of the buses.

Whatever data is available on the bus about the deadly crash, Lawrence notes that it’s not infallible and may not provide the much desired answers.

“It’s tempting to think that it’s going to answer every question and it may answer a whole bunch of them, but at the same time it may not,” said Lawrence. “Sometimes I find the data raises more questions than it answers.”