When you are carrying out mobile or short-duration works, the vehicle must be conspicuous: high visibility rear chevron markings are strongly recommended in England and Northern Ireland, and compulsory in Scotland and Wales (see the Vehicles (England and Northern Ireland) and Vehicles (Scotland and Wales) sections of this Code).
The vehicle must have one or more amber warning beacons such that at least one beacon can be seen from any direction. The beacon/s must be used for mobile works when the vehicle is travelling at less than the general speed of traffic. For short-duration static works, the beacons should remain on at all times.
A ‘Keep right/left’ sign must be displayed for drivers approaching the works on the same side of the carriageway, showing which side to pass.
Warning: Vehicle mounted ‘Keep right/left’ signs must be covered when the vehicle is travelling to and from the site. Do not simply turn the sign to point up or down.