A. After the traffic lights, but before the construction zone.
A. After the traffic lights, but before the construction zone.
B. Where the lane ends.
C. At the 'Stop here on red signal' sign.
Temporary traffic lights are positioned before road works where the type of traffic flow means that having a traffic controller could be wasteful (e.g. the traffic could be infrequent), and that there is enough room to place the traffic lights (sometimes this just isn't possible on narrow urban streets). The lights are placed far enough back so that road works vehicles can manoeuvre and that the lane of traffic that has to use the opposite side of the road has enough room to change lanes.
There is also a safety buffer between the traffic lights and the road works in that if a driver doesn't see the traffic lights until the last moment and can't stop in time, it's less likely that the driver will end up in the flow of traffic coming the opposite direction, or hitting a road worker.
If you have been waiting at one of these lights for a while and it hasn't changed make sure that you are stopped where the sensor can detect your vehicle.