In Baltimore we call this the Light Rail service, I don't remember what it's called here.
It's a one-line service for now, with future expansion planned. Basically follows Main Street....
This service just opened up in January '04. Since then, there have been over 35 Car-vs-Train accidents.
The most common cause? Cars illegally turning left, right in front of the trolleys.
Despite what you may have heard, Houston has a pretty good public transportation system that consists mostly of busses [www.ridemetro.org/services/publicguides.asp].
Additionally, there is a free trolley system
[www.ridemetro.org/pdf/routes/trolley.pdf] that runs downtown.
There is also as a relatively useless rail-line
[www.ridemetro.org/pdf/routes/700metrorail.pdf] that connects downtown to the Reliant Park / Astrodome area (via the Museum District and Medical Center).