Here's an interesting time-lapse video of crews replacing the tracks in the intersection of Church and 30th Streets on the San Francisco MUNI light rail system. The whole ($3,000,000) process from tearing up the pavement, to repaving is caught in this 12 minute long video.
http://vimeo.com/15780202
http://vimeo.com/15780202
Trains aren't dangerous, it's lack of common sense that's dangerous.