by Dick Falkenbury
The most important thing in transit is "life-cycle costs": construction, replacement, maintenance and labor and all costs over a hundred years. Include such things as insurance (including payouts for running over children), days (and hours) lost due to accidents, and all the rest.
There is no way to run a light rail on grade without labor (a driver). They have one of the very worst accident rates of any mode (per Federal Transit Administration, FTA). They have a lot of little accidents that require total stoppage.
I will concede that they have some small usage: Seattle's Waterfront Trolley moves (mostly tourist) along a short two mile route. It works, not as transportation but as a way for the tourism business. The drivers also act as ambassadors for the city. It even is a pretty good way to park about a mile from the stadiums and trolley within walking distance. It gets into some accidents (it never goes over 20 mph and has injured dozens and even killed one guy at three mph). It has a purpose--but it is not transit.
There is a town north of Seattle called LaConner: it is a little artist colony with ten thousand tourist a day going to galleries, shops and restaurants. The real problem is parking. They could park the cars in a field at one end and run a light rail very slowly down the main street. I see light rail as an answer when it solves a secondary problem over a very short distance, where speed is not important. But for moving tens of thousands of people three to ten miles (typical commute distance according to the FTA) economically, efficiently and safely--nothing beats monorail.