VC and ChrisL are correct that trains don't necessarily HAVE to be traffic stoppers. In many countries, train lengths are limited and the facilities are designed such that they don't obstruct traffic so badly - such as having them above/under the city and such that trains can pass through cities at higher speeds.
However, most of USA trains ARE freight cars. These are trains which are miles long, run at ground level, and slow down to a crawl as they choke through cities.
Granted, they could be made more practical, but right now the USA trains cause a lot of traffic stoppage. We have trains in our city which tie up traffic for more than 15 minutes at a time. The traffic can sometimes get backed up for almost a mile on both sides of the track.
Last edited by mike; 10-18-01 at 06:45 AM.