I drive that road v regularly, I live nearby. I drove it yesterday, both directions as I was working in the city during the day. As other people have said, it is a terrible bit of road and that whole stretch is notoriously dangerous. The A47 is our motorway iyswim. East/West across the county, that's your road. It is poorly maintained, often single carriageway, littered with agricultural vehicles and HGVs and vastly overpopulated by a whole county of people going to work, school or trying to get to the west/north. That stretch is bookended by dual carriageway, where you make appropriate progress and the road matches its users' needs. Then you suddenly hit snarled up traffic, ridiculous junctions, all with an inappropriate national speed limit, a misleading straight road which is actually hampered by distorted bends and an odd camber. If you know that road, you know to anticipate the mess of the junctions and the traffic problems which result.
Just a couple of things which struck me as a regular user of that road:
I presume the car which was overtaken was doing NSL. At that point on that road you expect and see cars turning across your lane and pulling out to join you from the junction up ahead. You have to allow other cars to join there in the time between you seeing and reaching the junction. At national speed limit from the point the bike overtakes to the point of accident, you can and should expect cars to be joining and leaving. There is time, space and sadly, necessity. Take out the motorbike (awful turn of phrase sorry) and it's unremarkable. At speed limit or under, the car turning would have been a normal, acceptable sight for that road.
Coming the other way, the car driver who caused the accident wouldn't have seen the overtaken car or bike because on his approach, presumably he was scanning for a large enough gap to turn. If he knew the road, I'm a!most certain he'd know that you don't look for a totally clear road, never could happen there. On approach he probably assessed the gap up to the point that he knew that if there was anything beyond that at NSL or even at 70, it wouldn't reach the junction before him. What he didn't consider was that a vehicle at 100mph would hit him. Nobody in their right mind would do 100mph there, no car could physically do it due to traffic volume and conditions. Only a bike could and yes you should always, always think bike but I'm going to admit that I would never, eve believe a biker could be considering doing 100mph there. I would have checked for bikes as I approached and then committed to turning. I wouldn't have seen a bike because at the point that I was assessing, the bike was too far away to impact my decision. Clear road, space to turn, nothing can gain that ground in 3 seconds surely?
Of course think bike would have prevented the accident. But not in isolation. Think bike and remember they might be capable of going way, way faster than you've ever seen on that road before and then you're nearer preventing that kind of accident. The car driver undoubtedly caused the accident in a simple cause and effect but change the biker's speed to NSL, same as the car he wouldn't even have been overtaking anyway and he physically wouldn't have been there.
I wish they would find the money to sort the road out. Even just reduce the speed for now. Further up the road, locals have probably seen the massive works at Postwick. I drive through to Thorpe daily ATM and the works temporary speed limit is 50. Does any fucker slow down? No. If you did, somebody would hit you but stay at 70+ and you risk an accident too as you jostle for lane too late. Two accidents I've seen there so far this week alone.