From a correspondent:

“Much the most important issue in choosing trams seems to me to be the cost per kilometre of installation rather than the length of the system. This is where Ultra Light Rail (as demonstrated at Stourbridge) comes out tops! The low weight of less than 5 tons axle loading combined with lighter rails and relative speed and ease of installation make the infrastructure very significantly less costly than conventional trams, such as those used in Nottingham (which cost almost £1 billion). This is more important even than the savings made on the lower cost of the vehicles. The capacity and speed of a ULR system can match the capacity and speed of a  conventional tram systems.

Siemens, Bombardier, Alstom and CAF seem to have a world monopoly on tram supply. This suits consultants wonderfully. They love a really expensive system as they work for percentages and 1% of £1000 million (like Nottingham) is much more attractive to consultants than a measly fee of only £1 million on a £100 million system. If you ask any consultant for advice the odds are that he will only tell you about the big 4 manufacturers.

People need to understand that underground services do not need diverting with  Ultra Light Rail trams.