I work on these, so here goes with an answer. Its bl00dy Health and Safety!!! It would appear we are too thick to be able to know when it is safe to enter/exit a section of roadworks. Currently we are working nights on the M1 near Milton Keynes and as you say, 3 lanes are coned off leaving 1 running lane. We are re surfacing, one lane at a time, so one lane is used for waiting and the other is the emergency lane (like I say H&S!). However, the Tarmac wagons park where they like blocking the whole place, but worst are those who are apparently 'in charge'. Not only do half of the 'high ups' in cars not have flashing lights etc (having given us a 3 hour induction to say how important safety gear is), but will then park their Ford Mondeo or similar right in the works access when you are trying to get in off the motorway from 50mph down to the site limit of 15mph and trying to stop half the traffic behind you acting like sheep and following you in! They are all total *********! If you do go in through the cones (even in a perfectly safe place) you will be banned from site. So called Health and Safety has got a lot to answer for!