Avoiding deadly bus collision was 'unlikely,' expert testifies
Driver Aissatou Diallo had little time to brake after the bus left Transitway, court hears
The driver behind the wheel of the OC-Transpo double-decker that crashed into Westboro station likely had no time to brake after unsuccessfully trying to regain control of the bus, a collision reconstruction expert testified Thursday.
Aissatou Diallo has pleaded not guilty to 38 charges of dangerous driving, including three counts of dangerous driving causing death, stemming from the fatal crash on Jan. 11, 2019.
Court has heard that from the moment the bus strayed onto the Transitway shoulder to the moment it struck the shelter overhang, Diallo never applied the brakes.
On Thursday, Richard Lamoureux of DFA Engineering Services Ltd. presented calculations indicating Diallo never had the time needed to bring the bus to a stop.
Lamoureux testified the bus was 56.5 metres from the shelter when Diallo can be heard on video saying "Oh my god" after failing to right the vehicle. At that moment, the bus was travelling 59 km/h in an area where the posted speed was 50 km/h, Lamoureux said.
Lamoureux said given that distance and speed, avoiding the collision would have been extremely difficult, especially given the normal perception-response delay of 1.5 seconds, as well as a built-in delay of half a second with the vehicle's braking system.
He said even adjusting for a quicker response of under one second, it's unlikely braking would have generated enough stopping force to avoid striking the shelter.
Any attempt to brake in time would have been further hampered by ice and snow in the gutter and shoulder approaching the station, Lamoureux said.
"At 59 km/h, had braking been initiated in response to the bus not responding to steering, it's very unlikely the bus would've been able to stop before colliding with the station," Lamoureux concluded.
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Lamoureux said if the bus had been travelling at 50 km/h, the posted speed limit, and if the driver had reacted quickly, it's possible the collision with the shelter could have been avoided.
Throttle applied, Crown suggests
In earlier testimony, Lamoureux argued there were actually four separate collisions: the bus first struck a snowbank, then sideswiped a rock wall, then hit another snowbank before plowing into the shelter awning.
During cross-examination, assistant Crown attorney Dallas Mack suggested Lamoureux had made a mistake when his report said there was no effect when Diallo applied the gas for two seconds after the rock wall collision.
Mack pointed out that according to the onboard computer, the double-decker's speed remained a constant 39 km/h even though it struck a second snowbank.
"One reason it didn't slow for a period of three seconds is that the throttle was applied," Mack said.
Lamoureux agreed Diallo had hit the gas, but stood by his earlier testimony that the engine computer is unreliable in recording speed during a collision.
Lamoureux's cross-examination is scheduled to continue Friday.