<snip loads of ot / foreign stuff>
We have one locally that also has lights. Yesterday the lights were out and the traffic was flowing much better than when they are on.
I think the main reason it all goes bad is 'some people' seem to give the lights priority (and/or often jumping the lights) and so pull onto the roundabout when there is nowhere to go and hence gridlocking the whole area. Not something can remember seeing at many other straight roundabouts, especially bigger ones (anyone blocking the roundabout would be hooted pretty quickly).
Some routes onto the roundabout aren't controlled by lights and there you get issues with people wanting to turn left getting aggravated by people wanting to go straight on, waiting for the pathway to become clear, 'holding them up'. If you sit in the right hand lane (also acceptable for going straight ahead) you often can't get onto the roundabout or aren't allowed in by people on the inside lane because they think you are trying to gain advantage at their expense. Once on the roundabout, the 'zip' process generally works (except for builders vans and BMWs / Audi's etc, who obviously have priority) as the two lanes on the roundabout go into one at the exit.
Is the weird half joggle / non(?) roundabout (on the A127) still there at our Rayleigh?
Cheers, T i m