Rule 289
Take special care on motorways and other high-speed dual carriageways. Lanes may be closed to traffic and a lower speed limit may apply. Works vehicles may be used to close lanes or carriageways for repairs. Where large ‘Keep Left’ or ‘Keep Right’ signs are displayed on the back, you MUST move over and pass the works vehicle on the side indicated and not return to the closed lane until you can see it is safe to do so. Where a vehicle displays the sign ‘CONVOY VEHICLE NO OVERTAKING’, you MUST NOT pass the vehicle. A flashing light arrow or red ‘X’ may also be used to make the works vehicle more visible from a distance and give earlier warning to drivers. Laws RTA 1988 sect 36 , TSRGD reg 3 and sched 13