From what I'm led to believe Edinburgh once had the 5th largest tram network in the world until they ripped out the tracks in the late 1950's. The city has an old road infrastructure that was built for a horse and cart and can't cope with current levels of traffic so why jam the roads with even more vehicles like trams? ...especially when it's been tried before.
I think they have let the people and future generations of this city down by choosing a cheap and easy option.
They should have built a subway instead.