I wondered if glare had a hand in this. I was driving my kid to school this morning (earlier, though) and the sun was absolutely brutal. If I understand the location of the crash (this is not the level crossing on Fallowfield, but on the transit way itself, a bit north/north-west of the Fallowfield crossing. The transitway points roughly NNW, so at 8:45AM the Sun would have been behind and to the right of the bus:
http://suncalc.net/#/45.3028,-75.734,16/2013.09.18/08:45
I could see the sun being in the eyes of the drivers going South (from downtown), but not the other way. Maybe there was indirect glare reflected from a bus heading the other way?