Tom Anderson wrote:
On Mon, 31 Oct 2005, thoss wrote:

In article , Clive D. W. Feather
writes

The main reason for choosing trams over trolleybuses for any given
scheme is capacity. My vague memory is that the Cross-London route
would require 40tph or 130tbph to provide the same capacity;
presumably the same applies on the Uxbridge Road.

That implies that a trolley-bus can carry only 30% of a tram's
passengers. Why not bigger trolley-buses, maybe bendy ones?

For the same reason we don't have bendy-buses the length of a train -
the presence of a track. The track guides the vehicle, at every point
along its length, over a very precisely defined path, with no input from
the driver. This makes it possible for a long, bendy vehicle to take
fairly sharp corners extremely safely.

ISTR the idea of a bus guided automatically by a signal from a cable
buried under the road, a sort of 'virtual tram'; that would presumably
allow much longer buses. I don't know if this is a real technology or a
pipe dream, though.

I believe the technology exists to have optically guided trolleybuses,
i.e. following something painted/otherwise marked in the road. A more
pipe-dream style idea has the buses actually following the trolley wires
themselves, subject to needing to maneouvre around obstacles and into
stops. The idea was that pulling into stops could essentially be an
automated procedure depending on the extension of the overhead arms and
feedback from a Kassel kerb at the stop (a specially designed kerb which
helps to guide vehicles to a suitable distance for level boarding).



--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London