One of these accident is clearly a result of terrible design. The other 2 seam to be a simple inevitable result of mixing trucks and cyclists together. When a truck driver makes a mistake the cyclists has no chance. The only lesson to learn from this is that even perfect vehicular cycling positioning in the middle of a roundabout can not protect you from a SMIDSY (Sorry Mate I Didn't See You).
Separation of trucks and bike traffic by time or space seams to be the only systematic measure that will help reduce these types of mixing mistakes. This can be done by route, traffic light, operational time restrictions, protected lanes etc...
Behaviour and technique can help when separation fails. However education and behaviour campaigns should not be seen as a primary strategy just because they are cheap. They have a value but only as a last resort.
Here is some good last resort advice:
"Always remember; if the truck is ahead, stay back.
If the truck is behind, get ahead.
In a nutshell, try to put as much clear space between yourself and any large vehicles at junctions as you safely can."