On Futility of Trains
Sure, everyone loves trains. I myself wax sentimental when it comes to a bygone age of great puffs of steam issuing forth from a great black locomotive. Sure, trains are great if you want to get somewhere far away and don't want to deal with the expense and tyranny of the local airport. However, it is my personal belief that using trains as a commuting tool doesn't work.
Commuter train lines are expensive to install, space-wasting, and immutable. Furthermore, they almost certainly deliver passengers to a place that nobody particularly wants to be: next to a train station. While so called 'light rail' is better in some respects (less noisy, less obtrusive) it still is inneffective. There are few cities that use trains well. The primary train-city is New York, with it's (in)famous subway system. However, New York's subway is only successful because driving around New York is severely prohibited by lack of parking and heavy traffic: It is quite literally a last resort. The subway doesn't clear up traffic, it allows people to get around despite the unweildy nature of traffic. Another city with successful train-based transit system is Tokyo. Tokyo's train system is successful because of the group-based nature of japanese society, and the expense of obtaining a driver's license.
In short, I don't believe trains will work for most cities. I would like to be proven wrong, but I don't see it anywhere in the near future. What is needed in a successful transit system is a large infrastructure of busses (including BRT), combined with carpooling, carsharing, and local access to some necessities within walking distance of homes.