Ultra Light Rail

particularly in the form of self-powered vehicles run on compressed natural gas and/or biomethane.

These have a couple of advantages over conventional trams:

(a) any roads used have to be reinforced either very little, or not at all - which cuts the cost, time and sheer disruption (as in Edinburgh now) of implementation dramatically;

(b) absence of electricity again cuts time and cost of implementation, and also reduces the energy wasted in converting carbon fuels to electricity and the transmission losses in getting electricity - however produced - to the trams.

However, ULRs are up against barriers to entry both from Heavy Rail requirements for robustness, and in the UK at least the Ministry for (Road) Transport, which prefers to fund guided bus lanes at a multiple of the cost of tracks.

This one in Cambridgeshire is a case in point

I confess it did strike me that there is no reason why rails couldn't have been laid in the concrete at the same time, and then the buses and ULR could both use it and may the best mode win......

Oh well, got to keep the bus shareholders happy I suppose.

"The future is already here -- it's just not very evenly distributed" William Gibson