Yes - it is used to carry out minor repairs to units at their home based stations. It is staffed by two technicians, and carries tools and whatever spare parts are thought to be needed.
They can also respond to incidents to perform running repairs on units on site, hence the blue lights!
Bigger problems require a tractor-trailer rig to move the problem unit to the central workshop.
Added by Mike Feldman on 21 July 2011.