On Fri, 11 Sep 2009 08:53:29 GMT, "Richard J."
wrote:

In most systems that doesn't happen, with large boarding/alighting
flows only occurring at a relatively small number of stops along the
route.

Bill Bolton
Sydney, Australia

This isn't "most systems". It's London, and all 6 of the central area
stations on Crossrail (the ones where 24tph are currently planned)
*will* have heavy boarding/alighting flows.

I can well believe that. In central Paris, RER line "A" has 50 second
dwell times (compared to an average of 18 seconds on the métro).