Spyke wrote in message ...

Of course, where there were tramlines already, they could use those, but
they were horrendously impractical.

Of course, you'd have to modify the tramlines with the return wire as
well. (Trams only need one wire as they return the current through the
rails).

Trollybus overhead infrastructure is a lot more complicated and
expensive than that for trams; it's not just a question of two wires
instead of one. This does not mean that there are no circumstances
where trolleybuses are the best answer, but it is a factor which has
to be considered.

Spyke wrote:


Of course, where there were tramlines already, they could use those, but
they were horrendously impractical.

Of course, you'd have to modify the tramlines with the return wire as
well. (Trams only need one wire as they return the current through the
rails).

AIUI in some places they chose the opposite solution - modified the
trolleybuses to return the current through the tram track. Did they ever
do this in London?

On Fri, 19 Dec 2003 00:29:34 +0000, Spyke wrote:


Of course, where there were tramlines already, they could use those, but
they were horrendously impractical.

Of course, you'd have to modify the tramlines with the return wire as
well. (Trams only need one wire as they return the current through the
rails).

Only one wire? What's all the others for then? It's a bloody mess up
there for Croydon Tramlink.

At least when you have trolleybuses you ONLY have two!

Proof? Have a look at
http://www.trolleybus.net/fullsize/tramlink/1031.jpg

David Bradley

On 19 Dec 2003 05:17:01 -0800, (Stephen
Furley) wrote:

Spyke wrote in message ...

Of course, where there were tramlines already, they could use those, but
they were horrendously impractical.

Of course, you'd have to modify the tramlines with the return wire as
well. (Trams only need one wire as they return the current through the
rails).

Trollybus overhead infrastructure is a lot more complicated and
expensive than that for trams; it's not just a question of two wires
instead of one. This does not mean that there are no circumstances
where trolleybuses are the best answer, but it is a factor which has
to be considered.

Historically this is true because of the multiplicity of routes that
used to operate in London and therefore overhead junctions were a
common sight. Junctions aside, there is substantially less wiring in
the sky for trolleybuses than is the case for tramway operation.

If there were a rebuild of a London trolleybus system of a similar
route mileage, complex overhead junction wiring would not necessarily
re-appear. Indeed for 'sensitive areas' their may be no overhead
wiring at all since two factors would come into play, on board APUs
[or battary operation] and the ability to automatically lower and
raise the booms.

For electric street transit ,where a routing does not use any former
heavy rail routes trolleybuses are the only sensible answer. That is
the right factor to be considered, no others.

In September 2003 the Landskrona Trolleybus system opened and here is
a picture taken of one of the vehicles:
http://www.aveuk.nildram.co.uk/trans.../P9270037a.JPG
You will notice the lack of complexity of the overhead wiring and
don't be foolled into thinking that if this was a tram there would
only be one wire. Cast your eyses upward in Croydon and you will see
what I mean.

David Bradley

David Bradley wrote:
On Fri, 19 Dec 2003 00:29:34 +0000, Spyke wrote:


Of course, where there were tramlines already, they could use
those, but they were horrendously impractical.

Of course, you'd have to modify the tramlines with the return wire as
well. (Trams only need one wire as they return the current through
the rails).

Only one wire? What's all the others for then? It's a bloody mess up
there for Croydon Tramlink.

At least when you have trolleybuses you ONLY have two!

Proof? Have a look at
http://www.trolleybus.net/fullsize/tramlink/1031.jpg

Only two? Er, have you seen this ...?
http://homepage.ntlworld.com/bruce.l...Vancouver7.JPG

:-)

--
Richard J.
(to e-mail me, swap uk and yon in address)

On Fri, 19 Dec 2003 23:42:38 GMT, "Richard J."
wrote:

David Bradley wrote:
On Fri, 19 Dec 2003 00:29:34 +0000, Spyke wrote:


Of course, where there were tramlines already, they could use
those, but they were horrendously impractical.

Of course, you'd have to modify the tramlines with the return wire as
well. (Trams only need one wire as they return the current through
the rails).

Only one wire? What's all the others for then? It's a bloody mess up
there for Croydon Tramlink.

At least when you have trolleybuses you ONLY have two!

Proof? Have a look at
http://www.trolleybus.net/fullsize/tramlink/1031.jpg

Only two? Er, have you seen this ...?
http://homepage.ntlworld.com/bruce.l...Vancouver7.JPG

:-)

Don't be silly - you know that the picture is of a trolleybus
yard/garage/depot which was built/created many decades ago. But then
I ask you this question: Which is better: electrical pollution
[allbeit enviromentally friendly] in the sky or diesel fumes in your
lungs? I know which I would rather have.

A trolleybus depot and surrounding stabling areas if built today would
have NO overhead wiring, or for that matter traction wire supports.

Doesn't get away from the fact that tramway overhead is much more
complex than that which would be built for trolleybuses.

David Bradley

David Bradley wrote in message . ..

Don't be silly - you know that the picture is of a trolleybus
yard/garage/depot which was built/created many decades ago. But then
I ask you this question: Which is better: electrical pollution
[allbeit enviromentally friendly] in the sky or diesel fumes in your
lungs? I know which I would rather have.

A trolleybus depot and surrounding stabling areas if built today would
have NO overhead wiring, or for that matter traction wire supports.

I doubt it. I can't imagine them having to want to go to the effort of
having to top up the batteries/diesel engine all the time to drive it
around off the wires and then have to rewire the bus every morning.
Putting the wires up is a once only task and compared to the cost of
the rest of the network the cost of putting up the wires at the depot
is probably minimal.

B2003