Marland wrote:
bob 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.

It is provided you’ve done the work to properly isolate the track return
current to prevent electrolytic corrosion problems. If not, it probably
means ripping the whole lot up again.


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
sections, plus I suspect the OLE then needs to be aligned more accurately,
thus making it more intrusive.


Anna Noyd-Dryver