Light rail - Paris. Wikimedia Commons
There are many magic incantations abroad at the moment!!
"We need light rail"
"light rail is faster"
"rail has much greater capacity"
"rail only needs one driver to pull hundreds of passengers so is much cheaper"
"rail is more environmentally friendly"
"buses don't have the capacity to handle large numbers"
"light rail attracts people who won't use buses"
All these statements are essentially half truths or outright gobbledy gook. They are lazy thinking - statements having some elements of truth or being partly true, but always only in certain specific situations. Or they ignore context and downstream effects.
The magic incantations above can not be assumed, wishful thinking doesn't work for major infrastructure. Light rail (or commuter rail) is not like tinkerbell's dust spread over a magic castle, "when you wish upon a star" etc - build it and it is guaranteed success.
Loud opinions can be loosely put but city planning needs precise and accurate forecasting and cost-benefit studies.
Let us not forget the original forecast for the Heritage Tram, back in 1995, was 1.3 million passenger trips a year - in fact it has never exceeded 300,000 passenger trips a year to the best of my knowledge. Council subsidies had to be rearranged!
I like that tram system - its elegant old trams - and I think it did a huge amount for tourist images of Christchurch, it has significant added cost benefit factors. As do the iconic cartoon friendly shuttle buses. Something unique and distinctive. In contrast a modernistic light rail is so common place to most European and Asian tourists that it will just be wallpaper, as meaningless as a picture of a bus, not an attraction in itself.
The idea that building a light rail through congested Riccarton will be faster, or address the need to get people making longer journeys (across the whole city) on to public transport is illogical; another idea that is highly suspect is that light rail will get people out of cars in a way buses will not.
There have been many successful rail and light rail lines (especially if you do not factor in the fixed costs) but there have also been plenty that bombed or failed to attract significant patronage or created unforseen side effects.
The comments bring home the complexity of evaluating such projects, of public transport in general
All that glitters is not gold; all that is green is not green. (How sad the Green Party, running on mythology and knee jerk rather than careful research, backed light rail in Christchurch!)
Fixed rail systems in particular in countries lacking density of population need to make sure they join a lot of dots and join them well, cleverly, astutely, they need to do this even to achieve minimum viability (ie not cost the taxpayer $10 per for every passenger boarding).
Doing public transport well is bloody difficult and needs utmost commitment to getting multiple factors right.
It is not a fool's game but attracts politicians nonetheless.