That's true. But it's also true that there is some presupposition of fault on the part of the vehicle driver by some posting here. We should either be happy with all wild speculation or none regarding what happened
It would be nice if any of the wild speculation exonerating the driver fitted in with where the bus came to rest, though:
In the picture, the bus is definitely beside the GBW, but just after the start of it. It looks like it must have veered across both lanes of the busway before crossing the cycle path and hitting the building. That is some serious swerving off the route. It is just about conceivable that some cyclist(s) may have got seriously confused and found themselves riding on the busway tracks, but previous comments about the high speed of the bus at this point still apply.
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I think the photo is taken from Hills Road bridge - as you can see from the following streetview without buses in the way, the track is fairly straight with good visibility at that point.
http://www.instantstreetview.com/@52.190804,0.134932,205.11h,-3.26p,3.55z
Also, it's signed as 15mph through the curve under that bridge:
http://www.instantstreetview.com/@52.192342,0.135562,195.28h,-4.69p,1z
so I doubt the bus could have been travelling so fast that the driver was unable to stop for a cyclist illegally riding contraflow on the track without exceeding the speed limit on the pre-track section and/or not looking. Maybe it was an MTBer bunnyhopping out of the shrubs between the busway and railway? Seems rather unlikely, though.
The behaviour of buses on the southern section and especially how they barge through the junction with the Addenbrookes branch is a large part of the reason why I rode between the station and Addenbrookes along Hills Road yesterday, despite the still-ongoing roadworks at the Long Road crossroads.