On 08/02/2019 15:54, Anna Noyd-Dryver wrote:
Marland wrote:

Or use twin conductors like a trolley bus.
There was a short section In Greenwich when the Royal Observatory was
still located there where stray current even from normal track would have
affected some instrumentation.
They were rare though and I don’t immediately recall another UK
installation.
Having gone to the trouble of avoiding overhead returning a few years later
and putting up twice as much would hardly be popular.

That would necessitate use of trolley poles, where pantographs are the
current standard fitment for new tramways.

No, trolley poles were needed because trolley buses wander over the
road. A tram could use dual pantographs similar to those sported by
trains using three-phase electrification.

--
Basil Jet - Current favourite song...
What by Bruce
https://www.youtube.com/watch?v=RtJEAud9vao

Bevan Price wrote:
On 08/02/19 4:14, Recliner wrote:
The DfT remains consistent in its dislike of OHLE

https://www.thetimes.co.uk/article/battery-powered-trams-to-beat-congestion-pzz3p9jk3?shareToken=d7efc8230f20d995b8ea4bff5daae 175



As usual, the incompetent DfT only thinks about short term costs of
initial construction, not the long term running / operating costs.

Batteries have a finite life. You can recharge them, but they eventually
deteriorate, hold less charge, and have to be replaced - and they are
not cheap to replace.

Moreover, you use additional energy to convey the weight of the
batteries on every journey, instead of getting energy from fixed
overhead wires to move a vehicle that is lighter due to the absence of
batteries.

And before anyone suggests fuel cells, they also have finite lives, and
to function, they often rely on the presence of rare, expensive,
precious metals (platinum, palladium, rhodium, etc.)

There are recycling processes for catalysts containing all of those
precious metals. Except in very small quantities they are too precious to
throw away.

--
Jeremy Double

Graeme Wall wrote:
On 08/02/2019 10:58, Bevan Price wrote:
On 08/02/19 4:14, Recliner wrote:
The DfT remains consistent in its dislike of OHLE

https://www.thetimes.co.uk/article/battery-powered-trams-to-beat-congestion-pzz3p9jk3?shareToken=d7efc8230f20d995b8ea4bff5daae 175





As usual, the incompetent DfT only thinks about short term costs of
initial construction, not the long term running / operating costs.

Batteries have a finite life. You can recharge them, but they eventually
deteriorate, hold less charge, and have to be replaced - and they are
not cheap to replace.

Moreover, you use additional energy to convey the weight of the
batteries on every journey, instead of getting energy from fixed
overhead wires to move a vehicle that is lighter due to the absence of
batteries.

And before anyone suggests fuel cells, they also have finite lives, and
to function, they often rely on the presence of rare, expensive,
precious metals (platinum, palladium, rhodium, etc.)


Though once you've done the difficult bit of the infrastructure,
actually getting the tracks in the road, adding OLE later is a much
simpler engineering task.

Based on schemes like Sheffield Supertram, the most disruptive and
expensive part of construction is re-routeing all of the underground
utilities to allow the tracks to be laid...

--
Jeremy Double

In message

, at 16:53:44 on Fri, 8 Feb 2019, Jeremy Double
remarked:

Based on schemes like Sheffield Supertram, the most disruptive and
expensive part of construction is re-routeing all of the underground
utilities to allow the tracks to be laid...

And of course the extension of the Edinburgh tram to Leith.

iirc they diverted most of the utilities and then cancelled the
extension.

How *is* that project going today?
--
Roland Perry

On 08/02/2019 16:51, Jeremy Double wrote:
Bevan Price wrote:
On 08/02/19 4:14, Recliner wrote:
The DfT remains consistent in its dislike of OHLE

https://www.thetimes.co.uk/article/battery-powered-trams-to-beat-congestion-pzz3p9jk3?shareToken=d7efc8230f20d995b8ea4bff5daae 175



As usual, the incompetent DfT only thinks about short term costs of
initial construction, not the long term running / operating costs.

Batteries have a finite life. You can recharge them, but they eventually
deteriorate, hold less charge, and have to be replaced - and they are
not cheap to replace.

Moreover, you use additional energy to convey the weight of the
batteries on every journey, instead of getting energy from fixed
overhead wires to move a vehicle that is lighter due to the absence of
batteries.

And before anyone suggests fuel cells, they also have finite lives, and
to function, they often rely on the presence of rare, expensive,
precious metals (platinum, palladium, rhodium, etc.)

There are recycling processes for catalysts containing all of those
precious metals. Except in very small quantities they are too precious to
throw away.


There was a claim that sweeping the main roads and processing the dirt
would be more effective than mining for the rare elements used in
catalytic converters as the percentage it contained was higher than in
the crude ore dug from the ground.

--
Graeme Wall
This account not read.

On 08/02/2019 16:53, Jeremy Double wrote:
Graeme Wall wrote:
On 08/02/2019 10:58, Bevan Price wrote:
On 08/02/19 4:14, Recliner wrote:
The DfT remains consistent in its dislike of OHLE

https://www.thetimes.co.uk/article/battery-powered-trams-to-beat-congestion-pzz3p9jk3?shareToken=d7efc8230f20d995b8ea4bff5daae 175





As usual, the incompetent DfT only thinks about short term costs of
initial construction, not the long term running / operating costs.

Batteries have a finite life. You can recharge them, but they eventually
deteriorate, hold less charge, and have to be replaced - and they are
not cheap to replace.

Moreover, you use additional energy to convey the weight of the
batteries on every journey, instead of getting energy from fixed
overhead wires to move a vehicle that is lighter due to the absence of
batteries.

And before anyone suggests fuel cells, they also have finite lives, and
to function, they often rely on the presence of rare, expensive,
precious metals (platinum, palladium, rhodium, etc.)


Though once you've done the difficult bit of the infrastructure,
actually getting the tracks in the road, adding OLE later is a much
simpler engineering task.

Based on schemes like Sheffield Supertram, the most disruptive and
expensive part of construction is re-routeing all of the underground
utilities to allow the tracks to be laid...


My point.

--
Graeme Wall
This account not read.

Basil Jet wrote:
On 08/02/2019 15:54, Anna Noyd-Dryver wrote:
Marland wrote:

Or use twin conductors like a trolley bus.
There was a short section In Greenwich when the Royal Observatory was
still located there where stray current even from normal track would have
affected some instrumentation.
They were rare though and I don’t immediately recall another UK
installation.
Having gone to the trouble of avoiding overhead returning a few years later
and putting up twice as much would hardly be popular.

That would necessitate use of trolley poles, where pantographs are the
current standard fitment for new tramways.

No, trolley poles were needed because trolley buses wander over the
road. A tram could use dual pantographs similar to those sported by
trains using three-phase electrification.


As I said in the text which you snipped:

"I suppose you could have twin pantographs as fitted for 3-phase on certain
mountain railways, though you might get polarity issues on single track
sections, plus I suspect the OLE then needs to be aligned more accurately,
thus making it more intrusive."


Anna Noyd-Dryver

On 08/02/2019 16:38, Basil Jet wrote:
On 08/02/2019 15:54, Anna Noyd-Dryver wrote:
Marland wrote:

Or use twin conductors like a trolley bus.
There was aÂ* short section In Greenwich when the Royal Observatory was
still located there where stray current even from normal track would
have
affected some instrumentation.
They were rare though and I don’t immediately recall another UK
installation.
Having gone to the trouble of avoiding overhead returning a few years
later
and putting up twice as much would hardly be popular.

That would necessitate use of trolley poles, where pantographs are the
current standard fitment for new tramways.

No, trolley poles were needed because trolley buses wander over the
road. A tram could use dual pantographs similar to those sported by
trains using three-phase electrification.


Sorry for snipping out the bit where you said exactly that... not sure
where my brain was there.

--
Basil Jet - Current favourite song...
What by Bruce
https://www.youtube.com/watch?v=RtJEAud9vao

On Fri, 8 Feb 2019 15:54:19 -0000 (UTC)
Anna Noyd-Dryver wrote:
Marland wrote:
Or use twin conductors like a trolley bus.
There was a short section In Greenwich when the Royal Observatory was
still located there where stray current even from normal track would have
affected some instrumentation.
They were rare though and I don’t immediately recall another UK
installation.
Having gone to the trouble of avoiding overhead returning a few years later
and putting up twice as much would hardly be popular.


That would necessitate use of trolley poles, where pantographs are the
current standard fitment for new tramways.

I suppose you could have twin pantographs as fitted for 3-phase on certain
mountain railways, though you might get polarity issues on single track

Install a bridge rectifier in the trams. Problem solved.

On 08/02/2019 16:58, Roland Perry wrote:
In message

, at 16:53:44 on Fri, 8 Feb 2019, Jeremy Double
remarked:

Based on schemes like Sheffield Supertram, the most disruptive and
expensive part of construction is re-routeing all of the underground
utilities to allow the tracks to be laid...

And of course the extension of the Edinburgh tram to Leith.

iirc they diverted most of the utilities and then cancelled the extension.

How *is* that project going today?

There are no shovels in the ground. The council insists that it is
happening, whilst putting up notices on lampposts asking for suggestions
as to how they can save money to balance their budget.