The city of Dublin, (metropop 1.6 million) capital of Ireland previously built two separate light rail lines, disconnected from each other, operating their light rail under the traditional word for "speed" LUAS. (If you visit this site check out the interactive map to see when the next tram is due at any particular stop!).
Ignoring capital costs, the light rail has exceeded expectations and is operated without subsidy generating an operating surplus. It is considered a great success, carrying around 30 million passengers a year. Extensions to lines were in opened in 2009 and 2010
This weekend a further extension has been opened to one of these lines on the LUAS network. The extension has been built as a Private Public Partnership and has cost Euros $150 million (NZ$262 millions) to travel 4.5 kilometres - NZ$59 million per kilometre to build. The extension is expected to carry 2 million passengers a year.