Much work on tramways used to be done at night to avoid disrupting services. The existence of specialist vehicles for this work was not particularly well known to the public and their provision is sometimes overlooked when planning tramways.
Some undertakings prefer to use specialist
multi-purpose vehicles whereas others
use old passenger trams which have been
adapted.
Old trams can very often be obtained very cheaply and there would
be particular benefits to the Bath system from buying these rather
than a single multi-purpose unit. A snowplough is required during
winter months and, with suitable adaptation, this could double
up as a grass-cutter in spring and summer. (Grassed
track?)
The depot may well require the services of a shunter when the
snowplough/grass-cutter is being used elsewhere, so a second vehicle
would be needed. If repairs are undertaken, a third vehicle with
mess accommodation and tools might also be required.
Other functions to be performed by these vehicles include track cleaning, transport for spares, towing 'dead' trams around the depot and broken-down ones back for repair. In addition, the works tram may incorporate a diesel engine and generator to enable it to run on track where the supply has been cut off or, in extreme cases, to provide power to a section of line so that services can continue under emergency conditions. A converter set will enable power tools to be run from a safe supply, derived from either the generator or the overhead wire.
The maintenance of overhead wiring in the past was often performed with the wiring 'live' and the tramway in operation. The workmen operated from a swivelling insulated platform on a tower waggon, which was swung aside to let trams past. The modern equivalent is a 'cherry picker' hydraulic arm with a fibreglass bucket to insulate the worker. this is usually mounted on a road vehicle.
