Re: buses or trams

[Greg Gritton <ggritton@ichips.intel.com>]

David Bromage wrote:
> 
> ralph buttigieg (ralphb@zip.com.au) wrote:
> > David Bromage wrote in message <7401j9$gbp$6@news.mel.aone.net.au>...
> > >One thing which hasn't taken off in Australia yet is what is generally
> > >called a "Metro", which is at the heavy end of light rail. It seems to
> > >work well in Europe and more recently the USA, so why not Australia?
> 
> > Is that the underground railways system like they have in Washington DC? Why
> > would we need that if above ground trains as possible?
> 
> The LA Metro would be a better example, as are Manchester and Tyneside in
> the UK. The Paris metro is probably a bad example, it is probably more on
> the light end of heavy rail than the heavy end of light rail.
> 
> A metro offers some of the benefits of heavy rail at very little
> additional cost, but retains the benefits of light rail. It doesn't
> necessarily have to be underground.
> 
> Cheers
> David

Isn't "metro" just a convenient word for a what is commonly
called a "subway" (i.e. heavy rail) that isn't necessarily underground.
LA's "metro" is a conventional subway, and was extremely expensive
to build per mile.  Mexico City's "Metro" is a heavy rail system that is
underground, grade level, and elevated in parts, with a design based 
on Paris's "metro".   I believe Paris was the original city to call 
its heavy rail system the "Metro".

Nowdays, the word is sometimes more generic, and has even been applied
to bus systems, such as in Seattle.  It is sort of like Rapid
Transit was a few years ago.  (LA's bus system used to be called
the RTD, for Rapid Transit Distric.)  I would not be surprised
to see it applied to light rail.

Does "metro" have a more specific meaning in some region of the world?

Finally, what does the "light end" of heavy rail mean.
Heavy rail cars are often lighter than light rail cars.
Generally, heavy rail has two characteristics that
seperate it from "light rail":

   1. Complete grade seperation* (permits higher speed)
   2. Long trains                (permits higher capacity)

Does the type of "metro" you are discussing compromise one of these?

Greg Gritton


* Some heavy rail systems might include protected grade crossings,
  but these are usually rare, and I don't think street
  running is ever included