DVSA Traffic Enforcement deals with commercial vehicles and their drivers, ensuring the vehicles are roadworthy, not overweight etc, and that driver hours are correct (amongst other things). They will direct vehicles to follow them to weigh bridges and testing sites to do so - and in some areas, Highways England Traffic Officers perform the same task on behalf of the DVSA, limited only to pulling in the vehicles, for DVSA officers to then carry out the checks.
Traffic Officers patrol the strategic road network, that being the motorways and major dual carriageways (not all dual carriageways).
Traffic Officers will respond in some capacity to any incident or problem, the extent of their involvement dependant on the nature of the incident. The obvious things being breakdowns, collisions, debris and obstructions, infrastructure defects, pedestrians and animals. The main priority of traffic officers is to keep the road clear, by removing the breakdowns, damaged vehicles and other obstructions as quickly as possible. When that isn’t possible (perhaps due to necessary police investigations) they will close lanes, carriageways or entire roads and direct traffic around or away from the problem. The same applies when something can’t be moved, like a vehicle stuck in gear or in “park” - although new kit is being introduced that will help get round those problems. They will upright and clear overturned vehicles, or failing that, drag them on their roofs if necessary, and if none of that is possible, arrange for appropriate recovery services.
When there is a serious incident, they will also clear traffic that is trapped between a closure and an incident scene (by turning it all around and finding a new route for it).
Other than lane closures, temporary mobile closures, known as rolling road blocks, are used to create clear road space while a problem is cleared up (moving vehicles, mopping up spills, repairing faults etc).
Because clearing the road is the priority, they have the means to tow pretty much any vehicle, up to and including 44 tonne LGVs.
They are trained in emergency first aid and trauma care, and carry defibrillators as well first aid kits. Traffic Officers cannot exceed speed limits, but do have some exemptions, such as passing a red X signal, crossing solid white lines and driving (or reversing) on hard shoulders. The vehicles will display red and amber lights to the rear, and amber at the front with alternating headlamp flash, to make progress through traffic, and although no sirens, they do have a bull horn for the same reason. If you hear the horn, and see amber lights and flashing headlamps behind you, they’re trying to reach (and clear up) an incident ahead of you - so treat it like a blue light vehicle and make room for them to pass as best is possible.
Traffic Officers don’t carry tools, water or fuel, and won’t make repairs, that is for breakdown and recovery services once the vehicles are cleared to a safe place.
Both DVSA and HE Traffic Officers have the same legal powers as the Police in regards to directing and managing traffic for the purposes of their roles, and it’s a criminal offence to disregard their instructions. For example, failing to stop when directed, or passing a rolling road block can result in points on you licence and significant fine - and not through fixed penalties, it’ll be an appearance in court.