We have these on bike lanes at intersections in the Netherlands.
In addition to everything already discussed here, they also have the role of asking for a green light automatically for you. If there are no cars travelling on Street ways contending with the bike lane, the light turns green. Alternatively, it turns green when you get your turn.
You can also ask for the green light by pushing a button, but it's nice that some intersections (the newer ones) don't require it.
However, I'm not sure if these can be configured to work for both cars and bikes at the same time.
Blitzer + Quasar + shield is fantastic