On Fri, 11 Nov 2005 07:42:41 +0000, David Bradley
wrote:
On Thu, 10 Nov 2005 10:02:33 +0000, "Clive D. W. Feather"
wrote:
In article , David Bradley
writes
There is
no experience whatsoever of 40 metre trams in UK streets, so we have no
knowledge of how they will fare even with their fixed path.
There is experience with coupled pairs in Manchester and even Blackpool.
We also have hundreds of years of experience of rail transport which
shows us that all the vehicles follow the same fixed path, whether the
combination is 5 or 500m long.
The issue is not that of the path of the tram. That is clearly defined by the
rails, as stated, The question is how you can fit the 40 metre length in the
street between junctions, tram stops, stationary traffic of one sort or
another, traffic 'nipping in' etc. Even with the flexibility of path available
(by steering) of a bus, 'bendies' on London routes often have to be guided
very carefully to be able to be squeezed into the available road space and
these are 18 metres long. The tram has to occupy 40 metres of carriageway at
any time. I believe that to get a clear 40 metres along some of the more
heavily congested sections of this road, may at many times prove difficult and
the tram will be delayed not because other traffic has stopped, but because of
its own size. A good analogy would be that of artic lorries which are often
unable to proceed even when other traffic is moving because there simply is
not enough carriageway into which they can fit. the tram will of course be
over twice the length of any artic lorry.
This sort of problem can be experienced daily (only to a lesser extent as the
trams are shorter than 40 metres) in those cities with extensive street
running of their trams and congested streets such as Turin for example.
The U9 (I think) that runs between Duesseldorf and Duisburg has a
considerable stretch of street running after it emerges from below
ground and before it goes onto reserved track north of the Messe.
When they run double units, it takes up almost all the road between
certain pairs of traffic signals. If that coincides with a tram stop,
it stops everything.
--
Terry Harper
Website Coordinator, The Omnibus Society
http://www.omnibussoc.org