Traffic Light Van Crew - What are they doing all day?

We have regulations that means that only properly trained and certified people are allowed to do traffic management works. i.e. setting up signs, putting out barriers, operating traffic lights. On some works, especially temporary works on main roads, someone needs to be there full time to monitor traffic and deal with any issues including signs and barriers being knocked over etc. Quite often its a requirement of insurance and the road closure permit that they be actively monitored and managed by an authorised person. The reason you don't see active monitoring on minor roads is that the lights will be routinely monitored (i.e. daily) and any failure inbetween won't cause enough of a problem to warrant active monitoring.