I spent over 15 years researching buses & trolleybuses in the UK and abroad. I only went on to light rail because it was clear from evidence around the world, that people with a car (most aspire) will not get on a bus, even a trolleybus, because it is considered to be qualitatively poorer, but will get on rail, which does not have potholes or swerves. This may explain why there are only c 75 trolleybus systems worldwide and over 600 tramways/light rail and growing.
My presentation at Energy4Power was about breaking out of public subsidy dependency and harnessing private investments to provide trams as an alternative to car use. In terms of energy use, the City Class tram (200 passengers) uses 1kWh/km. The tramlink trams (200 passengers) use 5kWh/km, a similar figure to 80 seat trolleybuses. Looking at transport from a “supply side”, misses the point that most people (with cars) have a choice. If public transport is not acceptable they will use their cars to go to places that can be reached by car. Hence the growth of out of town centres, and the problems of central areas. In the US virtually all the new light rail systems have been driven by city centre businesses that want to increase market catchment, without the need for automobile access (and expensive parking).
I hope that these few notes are of interest. There is much more in my book “Light rail developers’ handbook”, drawing on a large body of research over 40 years, mine and others worldwide, and reflecting ‘demand side’ considerations.