Addendum Stourport Bridge

The lights are playing up again, heading into town I watched the cars backing up along the single lane. The car left did the intelligent thing and waited at the green light instead of pulling over to the other lane and got red lit for their trouble. After a three-count however the lights switched back to green, followed by red, followed by green all within a tiny time period. Traffic is of course backing up through town and causing a feedback loop back to the bridge.

Now these aren't your bog-standard temporary traffic-lights these are sensor driven intelligent lights similar to those on fixed junctions, so why are we having so many difficulties with them?