A very interesting article (link below.)
http://www.christianwolmar.co.uk/articles/tt/dec15,06.shtml

CW argues that "The Department for Transport is particularly bad at challenging established thinking. It is always too ready to play safe without considering radical new options. Worse, once something becomes orthodoxy, such as rail franchising or PFIs for light rail schemes, then that becomes the only game in town."

Further quotes :

"A couple of recent examples spring to mind. The Department has taken a dislike to light rail schemes and, instead, is keen on guided busways which it sees as a cheaper and more flexible alternative. Indeed, it has approved a scheme for a 10-mile route converting an old rail line between St Ives and Cambridge, and is funding directly most of the staggering £116m cost. Similarly, another rail conversion scheme between Luton and Dunstable has received ministerial endorsement and is set for a public inquiry."

"But buses do not attract people out of their cars in the same way as rail, and an alternative that would not require ripping up the rails is an ultra-light rail system, using self-propelled trams. Several such schemes, which are far cheaper than conventional light rail, have been put forward by a company called Sustraco but have received short shrift from the Department despite clear cost and environmental advantages, Similarly, the Department refuses to look seriously at the possible funding of transport schemes through the profits made by nearby owners and developers."

The article also expands on the idea of rail reopenings to be funded by a roof tax levied on new housing built in the area concerned.