I have this all the time as I work in roadworks a lot. Basically, the drivers must obey any signs, whether stop/go boards or TL's (traffic lights), and surprise surprise, they quite often don't! Drivers seem to think the signs don't apply to them. If they do stop, when they get the green light they take off at 90 mph, seemingly oblivious to the workers/machinery that they are passing close to! However, back to your question. If the signs/lights are 'wrong', then the contractor is at fault. I have had cases where I have been driving my truck and the 'lollipop' man has let me drive past him so there was no way the drivers could see the stop/go board. Apparently it was his first (and possibly last) day. Legally, all 'countdown' signs (eg Roadworks 400yds), must be no closer to the roadworks than the yardage specified. They can be further away though, but I can't recall seeing if there is a maximum distance they can be away (if you see what I mean). Finally a little plea. We don't like holding the traffic up, as often it stops us from getting back to the job, so please bear with us. We are doing our best!! (Especial apologies if you were on the A47 near Collyweston this afternoon. Due to unforeseen problems we over ran by 2 1/2 hours!!)