If a vehicle stops or works on or beside a live carriageway, Chapter 8 of the Traffic Signs Manual applies to it. That covers highway maintenance gangs, utility crews, recovery trucks and traffic management. The guidance tells you how the vehicle should be marked and lit so approaching drivers see it early enough to react. Most people think of it as a signwriting job. On the build side, the beacon and conspicuity requirements end up shaping the electrical system far more than the vinyl does.
Where Chapter 8 sits
Chapter 8 is the part of the Department for Transport’s Traffic Signs Manual that deals with road works and temporary situations. It interprets the regulations in practical terms for signing, guarding and lighting a works site, and that includes the vehicles inside the site. Strictly it is guidance, not one hard legal limit. In practice highway authorities and their contractors make compliance a condition of working on the network, so for a converter it may as well be a specification.
The rear chevrons
The rear chevron panel is the part everyone recognises. The chevrons point upwards and alternate red and yellow. Red is the retroreflective colour and does the work at night when headlights hit it. Yellow is fluorescent and carries the daytime conspicuity. The width and angle of the stripes are specified so that the pattern still reads as chevrons from a distance, rather than turning into an orange smear.
Lettering matters too. Highway maintenance vehicles carry wording such as “Highway Maintenance”. “Motorway Maintenance” is only meant for vehicles whose work is confined to motorways.
Amber beacons and the rest of the lighting
A vehicle standing on a live road needs amber warning lamps that approaching traffic can see, and so does plant moving around inside the works area. On a current build that usually means a roof light bar or several beacons, with extra rear-facing warning lamps. Traffic management vehicles add a directional arrow or a message board on top.
Every one of those lamps should carry ECE R65 approval as a warning lamp and ECE R10 approval for electromagnetic compatibility. R65 covers how the lamp performs as a warning device. R10 means it will not throw interference into the vehicle’s radio, tracking or other electronics. We go through both marks in more detail in ECE R65 and R10 explained.
What the lighting does to the electrics
Here is the part that catches people out. A highway or utility vehicle can sit on site for hours with the engine off, beacons flashing, work lights on, the arrow board running and maybe a welfare heater or a tool charger plugged in. That is a long, steady drain on a battery that also has to crank a diesel at the end of the shift.
So the starter battery needs protecting. A Battery Guard watches battery voltage while the engine is off and drops the non-essential loads before the battery gets too low to start the vehicle. The Battery Guard 2000 does this at 100A or 200A on 12V and 24V. On a 12V model it only acts once the voltage has sat below 12.1V for four minutes, so a brief dip when a hydraulic pump kicks in is ignored.
Switching is the next decision. The old way is a relay and a fuse per lamp, a loom running the length of the chassis and a switch panel full of rockers nobody has labelled. A CAN switching system such as iConnex drives the beacons, work lights and boards from programmable outputs instead. The ICX-MOD-PRO module has ten FET outputs and two 30A relay outputs, works on 12V or 24V, and senses both the chassis and auxiliary batteries. The harness gets lighter and the build gets quicker. When a lamp stops working you can see which output it is on, which beats tracing a green wire through a bulkhead.
Bigger traffic management vehicles benefit from a task and power management controller. It can sequence the lighting and arrow board and shed lower-priority loads automatically as the battery voltage falls, so the beacons are the last thing to go.
If the vehicle runs an auxiliary battery or 230V tools, a DC-DC converter or charger and an inverter keep those loads fed and the batteries topped up. Size them for the real site duty, not the drive between jobs.
Doing it as one job
The markings and lamps decide what the vehicle has to show. The power system decides whether it can keep showing it through a full shift with the engine off. Specify approved lamps, protect the starter battery and run the switching through a controlled system, and the vehicle passes inspection and still starts at 6pm. All of the Intellitec control and protection hardware mentioned here is designed and built in the UK, and our amber light and utility page covers the rest of the kit we supply to the sector.