I was standing at farringdon today and watched a Thameslink train come into the
platform. Under the footbridge the 25KV wire looked like it was mere inches
above the roof of the train.

Given that EMUs seem to be around 6 inches lower than most locos in the UK
what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
60 headed down there? I presume certain stock must be banned from the route
for this reason.

On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
wrote:

>I was standing at farringdon today and watched a Thameslink train come into the
>platform. Under the footbridge the 25KV wire looked like it was mere inches
>above the roof of the train.
>
>Given that EMUs seem to be around 6 inches lower than most locos in the UK
>what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
>60 headed down there? I presume certain stock must be banned from the route
>for this reason.

We have a line here (Glasgow to Paisley Canal) where I believe the
procedure is to turn off the power if a diesel locomotive is to
traverse the route.

On Mon, 04 Dec 2023 17:01:50 +0000
Scott <newsgroups@gefion.myzen.co.uk> wrote:
>On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>wrote:
>
>>I was standing at farringdon today and watched a Thameslink train come into
>the
>>platform. Under the footbridge the 25KV wire looked like it was mere inches
>>above the roof of the train.
>>
>>Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
>>60 headed down there? I presume certain stock must be banned from the route
>>for this reason.
>
>We have a line here (Glasgow to Paisley Canal) where I believe the
>procedure is to turn off the power if a diesel locomotive is to
>traverse the route.

Makes sense. Though I'm thinking at farringdon the wire could be scraping the
roof of the loco. Perhaps during maintenance they raise it somehow as well
as switching power off.

On 04/12/2023 15:57, Muttley@dastardlyhq.com wrote:
> I was standing at farringdon today and watched a Thameslink train come into the
> platform. Under the footbridge the 25KV wire looked like it was mere inches
> above the roof of the train.
>
> Given that EMUs seem to be around 6 inches lower than most locos in the UK
> what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
> 60 headed down there? I presume certain stock must be banned from the route
> for this reason.
>

From another group:

Only class 31 , 33/2 and class 73 are route cleared due to a height
restriction ( minimum overhead line clearance ) mark 1 and 2 coaching
stock also cleared. The overhead line must be isolated (but not earthed)
15 mph speed restriction opening windows should be closed.

--
Remove the '+' and replace with 'plus' to reply by email

<Muttley@dastardlyhq.com> wrote:
> On Mon, 04 Dec 2023 17:01:50 +0000
> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>> On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>> wrote:
>>
>>> I was standing at farringdon today and watched a Thameslink train come into
>> the
>>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>>> above the roof of the train.
>>>
>>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
>>> 60 headed down there? I presume certain stock must be banned from the route
>>> for this reason.
>>
>> We have a line here (Glasgow to Paisley Canal) where I believe the
>> procedure is to turn off the power if a diesel locomotive is to
>> traverse the route.
>
> Makes sense. Though I'm thinking at farringdon the wire could be scraping the
> roof of the loco. Perhaps during maintenance they raise it somehow as well
> as switching power off.

This photo indicates that it's a conductor bar, rather than a wire, and the
gap seems a little more than you thought (not my photo):

https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox/

Recliner <recliner.usenet@gmail.com> wrote:
> <Muttley@dastardlyhq.com> wrote:
>> On Mon, 04 Dec 2023 17:01:50 +0000
>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>> On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>>> wrote:
>>>
>>>> I was standing at farringdon today and watched a Thameslink train come into
>>> the
>>>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>>>> above the roof of the train.
>>>>
>>>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
>>>> 60 headed down there? I presume certain stock must be banned from the route
>>>> for this reason.
>>>
>>> We have a line here (Glasgow to Paisley Canal) where I believe the
>>> procedure is to turn off the power if a diesel locomotive is to
>>> traverse the route.
>>
>> Makes sense. Though I'm thinking at farringdon the wire could be scraping the
>> roof of the loco. Perhaps during maintenance they raise it somehow as well
>> as switching power off.
>
> This photo indicates that it's a conductor bar, rather than a wire, and the
> gap seems a little more than you thought (not my photo):
>
> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox/

Or is that actually St Pancras?

Alan Lee <alan@darkroom.plus.com> wrote:
> On 04/12/2023 15:57, Muttley@dastardlyhq.com wrote:
>> I was standing at farringdon today and watched a Thameslink train come into the
>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>> above the roof of the train.
>>
>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
>> 60 headed down there? I presume certain stock must be banned from the route
>> for this reason.
>>
>
> From another group:
>
> Only class 31 , 33/2 and class 73 are route cleared due to a height
> restriction ( minimum overhead line clearance ) mark 1 and 2 coaching
> stock also cleared. The overhead line must be isolated (but not earthed)
> 15 mph speed restriction opening windows should be closed.

I wonder what traction is used for maintenance trains? Perhaps they hire
in GBRf 73s?

Recliner <recliner.usenet@gmail.com> wrote:
> Recliner <recliner.usenet@gmail.com> wrote:
>> <Muttley@dastardlyhq.com> wrote:
>>> On Mon, 04 Dec 2023 17:01:50 +0000
>>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>>> On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>>>> wrote:
>>>>
>>>>> I was standing at farringdon today and watched a Thameslink train come into
>>>> the
>>>>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>>>>> above the roof of the train.
>>>>>
>>>>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>>>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
>>>>> 60 headed down there? I presume certain stock must be banned from the route
>>>>> for this reason.
>>>>
>>>> We have a line here (Glasgow to Paisley Canal) where I believe the
>>>> procedure is to turn off the power if a diesel locomotive is to
>>>> traverse the route.
>>>
>>> Makes sense. Though I'm thinking at farringdon the wire could be scraping the
>>> roof of the loco. Perhaps during maintenance they raise it somehow as well
>>> as switching power off.
>>
>> This photo indicates that it's a conductor bar, rather than a wire, and the
>> gap seems a little more than you thought (not my photo):
>>
>> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox/
>
> Or is that actually St Pancras?

I thought for a moment that I could see a TVM430 block marker (I’m sure
there’s another name which I can’t recall just now) so it must be StP.
Then I realised it wasn’t - the yellow is an arrow not a triangle - and
anyway e* trains don’t run through SPILL. So it could be anywhere as far
as I’m concerned!

Sam

--
The entity formerly known as Sam.Wilson@ed.ac.uk
Spit the dummy to reply

Sam Wilson wrote:

> Recliner <recliner.usenet@gmail.com> wrote:
>> Recliner <recliner.usenet@gmail.com> wrote:
>>
>>> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox/
>>
>> Or is that actually St Pancras?
>
> I thought for a moment that I could see a TVM430 block marker (I’m sure
> there’s another name which I can’t recall just now) so it must be StP.
> Then I realised it wasn’t - the yellow is an arrow not a triangle - and
> anyway e* trains don’t run through SPILL. So it could be anywhere as far
> as I’m concerned!

The page that images appears to come from, says it is StP

<https://www.modernrailways.com/article/signalling-tomorrows-railway>

"ETCS L2 with ATO overlay: a Class 700 passes an ETCS marker board in
the six foot at St Pancras International low level"

Sam Wilson <ukr@dummy.wislons.fastmail.co.uk> wrote:
> Recliner <recliner.usenet@gmail.com> wrote:
>> Recliner <recliner.usenet@gmail.com> wrote:
>>> <Muttley@dastardlyhq.com> wrote:
>>>> On Mon, 04 Dec 2023 17:01:50 +0000
>>>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>>>> On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>>>>> wrote:
>>>>>
>>>>>> I was standing at farringdon today and watched a Thameslink train come into
>>>>> the
>>>>>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>>>>>> above the roof of the train.
>>>>>>
>>>>>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>>>>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
>>>>>> 60 headed down there? I presume certain stock must be banned from the route
>>>>>> for this reason.
>>>>>
>>>>> We have a line here (Glasgow to Paisley Canal) where I believe the
>>>>> procedure is to turn off the power if a diesel locomotive is to
>>>>> traverse the route.
>>>>
>>>> Makes sense. Though I'm thinking at farringdon the wire could be scraping the
>>>> roof of the loco. Perhaps during maintenance they raise it somehow as well
>>>> as switching power off.
>>>
>>> This photo indicates that it's a conductor bar, rather than a wire, and the
>>> gap seems a little more than you thought (not my photo):
>>>
>>> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox/
>>
>> Or is that actually St Pancras?
>
> I thought for a moment that I could see a TVM430 block marker (I’m sure
> there’s another name which I can’t recall just now) so it must be StP.

Yes, it's definitely SPILL — you can just see the last few letters of
'International' to the right of the train. I'd missed that before posting.

> Then I realised it wasn’t - the yellow is an arrow not a triangle - and
> anyway e* trains don’t run through SPILL.

It's a block section marker for the in-cab automated signalling through the
TL core, so nothing to do with the HS1 route upstairs.

On 04.12.23 18:24, Recliner wrote:
> <Muttley@dastardlyhq.com> wrote:
>> On Mon, 04 Dec 2023 17:01:50 +0000
>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>> On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>>> wrote:
>>>
>>>> I was standing at farringdon today and watched a Thameslink train come into
>>> the
>>>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>>>> above the roof of the train.
>>>>
>>>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high class
>>>> 60 headed down there? I presume certain stock must be banned from the route
>>>> for this reason.
>>>
>>> We have a line here (Glasgow to Paisley Canal) where I believe the
>>> procedure is to turn off the power if a diesel locomotive is to
>>> traverse the route.
>>
>> Makes sense. Though I'm thinking at farringdon the wire could be scraping the
>> roof of the loco. Perhaps during maintenance they raise it somehow as well
>> as switching power off.
>
> This photo indicates that it's a conductor bar, rather than a wire, and the
> gap seems a little more than you thought (not my photo):
>
> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox/

That's SPILL. Farringdon has conventional OHLE while SPILL has bar
conductors. The sign on the far right has Underground, National Rail and
International Trains as its three labels, and the station name sign just
behind the cab ends "ational".

Looking at a few photos, my perception is the OHLE height in Farringdon
is higher than at the old King's Cross Thameslink, which was very low
indeed.

Robin

On Mon, 04 Dec 2023 17:24:29 GMT
Recliner <recliner.usenet@gmail.com> wrote:
><Muttley@dastardlyhq.com> wrote:
>> On Mon, 04 Dec 2023 17:01:50 +0000
>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>> On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>>> wrote:
>>>
>>>> I was standing at farringdon today and watched a Thameslink train come into
>
>>> the
>>>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>
>>>> above the roof of the train.
>>>>
>>>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high
>class
>>>> 60 headed down there? I presume certain stock must be banned from the route
>
>>>> for this reason.
>>>
>>> We have a line here (Glasgow to Paisley Canal) where I believe the
>>> procedure is to turn off the power if a diesel locomotive is to
>>> traverse the route.
>>
>> Makes sense. Though I'm thinking at farringdon the wire could be scraping the
>
>> roof of the loco. Perhaps during maintenance they raise it somehow as well
>> as switching power off.
>
>This photo indicates that it's a conductor bar, rather than a wire, and the
>gap seems a little more than you thought (not my photo):
>
>https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox
>/

I said farringdon, not St P.

On Tue, 5 Dec 2023 08:57:31 +0100
Bob <bob@domain.com> wrote:
>On 04.12.23 18:24, Recliner wrote:
>> This photo indicates that it's a conductor bar, rather than a wire, and the
>> gap seems a little more than you thought (not my photo):
>>
>>
>https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox
>/
>
>That's SPILL. Farringdon has conventional OHLE while SPILL has bar
>conductors. The sign on the far right has Underground, National Rail and
>International Trains as its three labels, and the station name sign just
>behind the cab ends "ational".
>
>Looking at a few photos, my perception is the OHLE height in Farringdon
>is higher than at the old King's Cross Thameslink, which was very low
>indeed.

It seems to be low pretty much everywhere on that part of the line. I'm
impressed they managed to squeeze it in at all with sufficient clearance.

<Muttley@dastardlyhq.com> wrote:
> On Mon, 04 Dec 2023 17:24:29 GMT
> Recliner <recliner.usenet@gmail.com> wrote:
>> <Muttley@dastardlyhq.com> wrote:
>>> On Mon, 04 Dec 2023 17:01:50 +0000
>>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>>> On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>>>> wrote:
>>>>
>>>>> I was standing at farringdon today and watched a Thameslink train come into
>>
>>>> the
>>>>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>>
>>>>> above the roof of the train.
>>>>>
>>>>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>>>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high
>> class
>>>>> 60 headed down there? I presume certain stock must be banned from the route
>>
>>>>> for this reason.
>>>>
>>>> We have a line here (Glasgow to Paisley Canal) where I believe the
>>>> procedure is to turn off the power if a diesel locomotive is to
>>>> traverse the route.
>>>
>>> Makes sense. Though I'm thinking at farringdon the wire could be scraping the
>>
>>> roof of the loco. Perhaps during maintenance they raise it somehow as well
>>> as switching power off.
>>
>> This photo indicates that it's a conductor bar, rather than a wire, and the
>> gap seems a little more than you thought (not my photo):
>>
>> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox
>> /
>
> I said farringdon, not St P.

Yes, I seached for images of class 700s at Farringdon, and that one came
up. Only after posting did I realise that it was taken at St Pancras. I
promptly posted a correction.

On 05/12/2023 10:29, Recliner wrote:
> <Muttley@dastardlyhq.com> wrote:
>> On Mon, 04 Dec 2023 17:24:29 GMT
>> Recliner <recliner.usenet@gmail.com> wrote:
>>> <Muttley@dastardlyhq.com> wrote:
>>>> On Mon, 04 Dec 2023 17:01:50 +0000
>>>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>>>> On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>>>>> wrote:
>>>>>
>>>>>> I was standing at farringdon today and watched a Thameslink train come into
>>>
>>>>> the
>>>>>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>>>
>>>>>> above the roof of the train.
>>>>>>
>>>>>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>>>>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high
>>> class
>>>>>> 60 headed down there? I presume certain stock must be banned from the route
>>>
>>>>>> for this reason.
>>>>>
>>>>> We have a line here (Glasgow to Paisley Canal) where I believe the
>>>>> procedure is to turn off the power if a diesel locomotive is to
>>>>> traverse the route.
>>>>
>>>> Makes sense. Though I'm thinking at farringdon the wire could be scraping the
>>>
>>>> roof of the loco. Perhaps during maintenance they raise it somehow as well
>>>> as switching power off.
>>>
>>> This photo indicates that it's a conductor bar, rather than a wire, and the
>>> gap seems a little more than you thought (not my photo):
>>>
>>> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox
>>> /
>>
>> I said farringdon, not St P.
>
> Yes, I seached for images of class 700s at Farringdon, and that one came
> up. Only after posting did I realise that it was taken at St Pancras. I
> promptly posted a correction.

That's the bane of my life.

Unfortunately search engines prioritise the most popular websites over
exactly what you search for. If you're searching for something a bit
obscure you can be stuffed.

Coffee <martin.coffee@round-midnight.org.uk> wrote:
> On 05/12/2023 10:29, Recliner wrote:
>> <Muttley@dastardlyhq.com> wrote:
>>> On Mon, 04 Dec 2023 17:24:29 GMT
>>> Recliner <recliner.usenet@gmail.com> wrote:
>>>> <Muttley@dastardlyhq.com> wrote:
>>>>> On Mon, 04 Dec 2023 17:01:50 +0000
>>>>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>>>>> On Mon, 4 Dec 2023 15:57:33 -0000 (UTC), Muttley@dastardlyhq.com
>>>>>> wrote:
>>>>>>
>>>>>>> I was standing at farringdon today and watched a Thameslink train come into
>>>>
>>>>>> the
>>>>>>> platform. Under the footbridge the 25KV wire looked like it was mere inches
>>>>
>>>>>>> above the roof of the train.
>>>>>>>
>>>>>>> Given that EMUs seem to be around 6 inches lower than most locos in the UK
>>>>>>> what on earth would happen if say a 12'9 class 66 or worse a 13ft high
>>>> class
>>>>>>> 60 headed down there? I presume certain stock must be banned from the route
>>>>
>>>>>>> for this reason.
>>>>>>
>>>>>> We have a line here (Glasgow to Paisley Canal) where I believe the
>>>>>> procedure is to turn off the power if a diesel locomotive is to
>>>>>> traverse the route.
>>>>>
>>>>> Makes sense. Though I'm thinking at farringdon the wire could be scraping the
>>>>
>>>>> roof of the loco. Perhaps during maintenance they raise it somehow as well
>>>>> as switching power off.
>>>>
>>>> This photo indicates that it's a conductor bar, rather than a wire, and the
>>>> gap seems a little more than you thought (not my photo):
>>>>
>>>> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox
>>>> /
>>>
>>> I said farringdon, not St P.
>>
>> Yes, I seached for images of class 700s at Farringdon, and that one came
>> up. Only after posting did I realise that it was taken at St Pancras. I
>> promptly posted a correction.
>
> That's the bane of my life.
>
> Unfortunately search engines prioritise the most popular websites over
> exactly what you search for. If you're searching for something a bit
> obscure you can be stuffed.

I think it found a page featuring that line, with pictures taken at both
(and possibly other) stations, but the individual images don't always show
where they were taken. I was too focused on looking at the OHLE height to
notice the platform differences.

On Mon, 4 Dec 2023 17:48:57 +0000, Andy Burns <usenet@andyburns.uk> wrote:

>Sam Wilson wrote:
>
>> Recliner <recliner.usenet@gmail.com> wrote:
>>> Recliner <recliner.usenet@gmail.com> wrote:
>>>
>>>> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox/
>>>
>>> Or is that actually St Pancras?
>>
>> I thought for a moment that I could see a TVM430 block marker (I’m sure
>> there’s another name which I can’t recall just now) so it must be StP.
>> Then I realised it wasn’t - the yellow is an arrow not a triangle - and
>> anyway e* trains don’t run through SPILL. So it could be anywhere as far
>> as I’m concerned!
>
>The page that images appears to come from, says it is StP
>
><https://www.modernrailways.com/article/signalling-tomorrows-railway>
>
>"ETCS L2 with ATO overlay: a Class 700 passes an ETCS marker board in
>the six foot at St Pancras International low level"

Yes, my mistake.

<Muttley@dastardlyhq.com> wrote:
> On Tue, 5 Dec 2023 08:57:31 +0100
> Bob <bob@domain.com> wrote:
>> On 04.12.23 18:24, Recliner wrote:
>>> This photo indicates that it's a conductor bar, rather than a wire, and the
>>> gap seems a little more than you thought (not my photo):
>>>
>>>
>> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox
>> /
>>
>> That's SPILL. Farringdon has conventional OHLE while SPILL has bar
>> conductors. The sign on the far right has Underground, National Rail and
>> International Trains as its three labels, and the station name sign just
>> behind the cab ends "ational".
>>
>> Looking at a few photos, my perception is the OHLE height in Farringdon
>> is higher than at the old King's Cross Thameslink, which was very low
>> indeed.
>
> It seems to be low pretty much everywhere on that part of the line. I'm
> impressed they managed to squeeze it in at all with sufficient clearance.
>
>

Although the voltage would have been lower I have wondered at how the
subsurface lines would have looked if the Met had got its way and the Ganz
3 phase system with its two overhead wires had been installed. Junctions
would have looked quite complicated because of the need to have large
neutral sections where one phase crossed another, trolley buses have them
as well where + and - wires cross but they only need a few inches for a
trolley head whereas pantographs are a lot wider.
Maybe Trolley poles were planned for the Met scheme bit I don’t know if
planning to that level of detail was done before before the Met was forced
to adopt the DC system .

GH

On 5 Dec 2023 14:54:45 GMT
Marland <gemehabal@btinternet.co.uk> wrote:
><Muttley@dastardlyhq.com> wrote:
>> On Tue, 5 Dec 2023 08:57:31 +0100
>> Bob <bob@domain.com> wrote:
>>> On 04.12.23 18:24, Recliner wrote:
>>>> This photo indicates that it's a conductor bar, rather than a wire, and the
>
>>>> gap seems a little more than you thought (not my photo):
>>>>
>>>>
>>>
>https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox
>
>>> /
>>>
>>> That's SPILL. Farringdon has conventional OHLE while SPILL has bar
>>> conductors. The sign on the far right has Underground, National Rail and
>>> International Trains as its three labels, and the station name sign just
>>> behind the cab ends "ational".
>>>
>>> Looking at a few photos, my perception is the OHLE height in Farringdon
>>> is higher than at the old King's Cross Thameslink, which was very low
>>> indeed.
>>
>> It seems to be low pretty much everywhere on that part of the line. I'm
>> impressed they managed to squeeze it in at all with sufficient clearance.
>>
>>
>
>Although the voltage would have been lower I have wondered at how the
>subsurface lines would have looked if the Met had got its way and the Ganz
>3 phase system with its two overhead wires had been installed. Junctions

Good thing they didn't. For a metro system in tunnel without any level
crossings and relatively low speeds 3rd/4th rail is probably a better choice
than overhead.

>would have looked quite complicated because of the need to have large
>neutral sections where one phase crossed another, trolley buses have them
>as well where + and - wires cross but they only need a few inches for a
>trolley head whereas pantographs are a lot wider.

Problem with trolley wires is they need their own little points to guide the
pole onto the correct wire which I imagine makes route setting as complex as
any tram system. Perhaps today with smarter AI systems the bus could move the
pole appropriately itself.

<Muttley@dastardlyhq.com> wrote:
> On 5 Dec 2023 14:54:45 GMT
> Marland <gemehabal@btinternet.co.uk> wrote:
>> <Muttley@dastardlyhq.com> wrote:
>>> On Tue, 5 Dec 2023 08:57:31 +0100
>>> Bob <bob@domain.com> wrote:
>>>> On 04.12.23 18:24, Recliner wrote:
>>>>> This photo indicates that it's a conductor bar, rather than a wire, and the
>>
>>>>> gap seems a little more than you thought (not my photo):
>>>>>
>>>>>
>>>>
>> https://www.flickr.com/photos/136510631@N08/30294141508/in/photostream/lightbox
>>
>>>> /
>>>>
>>>> That's SPILL. Farringdon has conventional OHLE while SPILL has bar
>>>> conductors. The sign on the far right has Underground, National Rail and
>>>> International Trains as its three labels, and the station name sign just
>>>> behind the cab ends "ational".
>>>>
>>>> Looking at a few photos, my perception is the OHLE height in Farringdon
>>>> is higher than at the old King's Cross Thameslink, which was very low
>>>> indeed.
>>>
>>> It seems to be low pretty much everywhere on that part of the line. I'm
>>> impressed they managed to squeeze it in at all with sufficient clearance.
>>>
>>>
>>
>> Although the voltage would have been lower I have wondered at how the
>> subsurface lines would have looked if the Met had got its way and the Ganz
>> 3 phase system with its two overhead wires had been installed. Junctions
>
> Good thing they didn't. For a metro system in tunnel without any level
> crossings and relatively low speeds 3rd/4th rail is probably a better choice
> than overhead.

The 3-phase system would have been really hard to squeeze into a tunnel,
though, of course, the Jungfraubahn does exactly that:

<https://www.flickr.com/photos/recliner/7683489358/in/album-72157630773147320/lightbox/>

On Tue, 05 Dec 2023 16:24:36 GMT
Recliner <recliner.usenet@gmail.com> wrote:
>The 3-phase system would have been really hard to squeeze into a tunnel,
>though, of course, the Jungfraubahn does exactly that:
>
><https://www.flickr.com/photos/recliner/7683489358/in/album-72157630773147320/l
>ightbox/>

I wonder what the reasoning was that this was a better solution than a single
wire with DC or single phase AC.

On 05.12.23 17:42, Muttley@dastardlyhq.com wrote:
> On Tue, 05 Dec 2023 16:24:36 GMT
> Recliner <recliner.usenet@gmail.com> wrote:
>> The 3-phase system would have been really hard to squeeze into a tunnel,
>> though, of course, the Jungfraubahn does exactly that:
>>
>> <https://www.flickr.com/photos/recliner/7683489358/in/album-72157630773147320/l
>> ightbox/>
>
> I wonder what the reasoning was that this was a better solution than a single
> wire with DC or single phase AC.

At the time of construction of the Jungraubahn (and other 3 phase
systems like that proposed for the Met), single phase AC was difficult
to work with in a railway environment due to the lack of rail compatible
rectifiers at that time. DC has its own limitations that were, and
remain, quite restrictive.

Robin

On Tue, 5 Dec 2023 17:53:55 +0100
Bob <bob@domain.com> wrote:
>On 05.12.23 17:42, Muttley@dastardlyhq.com wrote:
>> On Tue, 05 Dec 2023 16:24:36 GMT
>> Recliner <recliner.usenet@gmail.com> wrote:
>>> The 3-phase system would have been really hard to squeeze into a tunnel,
>>> though, of course, the Jungfraubahn does exactly that:
>>>
>>>
><https://www.flickr.com/photos/recliner/7683489358/in/album-72157630773147320/l
>
>>> ightbox/>
>>
>> I wonder what the reasoning was that this was a better solution than a single
>
>> wire with DC or single phase AC.
>
>At the time of construction of the Jungraubahn (and other 3 phase
>systems like that proposed for the Met), single phase AC was difficult
>to work with in a railway environment due to the lack of rail compatible
>rectifiers at that time. DC has its own limitations that were, and
>remain, quite restrictive.

Could they not just tap a single phase?

On Tue, 05 Dec 2023 17:03:29 +0000, Muttley wrote:

> On Tue, 5 Dec 2023 17:53:55 +0100 Bob <bob@domain.com> wrote:
>>On 05.12.23 17:42, Muttley@dastardlyhq.com wrote:
>>> On Tue, 05 Dec 2023 16:24:36 GMT Recliner <recliner.usenet@gmail.com>
>>> wrote:
>>>> The 3-phase system would have been really hard to squeeze into a
>>>> tunnel,
>>>> though, of course, the Jungfraubahn does exactly that:
>>>>
>>>>
>><https://www.flickr.com/photos/recliner/7683489358/in/
album-72157630773147320/l
>>
>>>> ightbox/>
>>>
>>> I wonder what the reasoning was that this was a better solution than a
>>> single
>>
>>> wire with DC or single phase AC.
>>
>>At the time of construction of the Jungraubahn (and other 3 phase
>>systems like that proposed for the Met), single phase AC was difficult
>>to work with in a railway environment due to the lack of rail compatible
>>rectifiers at that time. DC has its own limitations that were, and
>>remain, quite restrictive.
>
> Could they not just tap a single phase?

I suspect that single-phase AC motors were not up to the job - possibly
still aren't!

Single-phase is rectified to DC and either used as per DC traction or
inverted back up to variable-frequency-variable-current to drive 3-phase
traction motors.

nib

On 05.12.23 18:03, Muttley@dastardlyhq.com wrote:
> On Tue, 5 Dec 2023 17:53:55 +0100
> Bob <bob@domain.com> wrote:
>> On 05.12.23 17:42, Muttley@dastardlyhq.com wrote:
>>> On Tue, 05 Dec 2023 16:24:36 GMT
>>> Recliner <recliner.usenet@gmail.com> wrote:
>>>> The 3-phase system would have been really hard to squeeze into a tunnel,
>>>> though, of course, the Jungfraubahn does exactly that:
>>>>
>>>>
>> <https://www.flickr.com/photos/recliner/7683489358/in/album-72157630773147320/l
>>
>>>> ightbox/>
>>>
>>> I wonder what the reasoning was that this was a better solution than a single
>>
>>> wire with DC or single phase AC.
>>
>> At the time of construction of the Jungraubahn (and other 3 phase
>> systems like that proposed for the Met), single phase AC was difficult
>> to work with in a railway environment due to the lack of rail compatible
>> rectifiers at that time. DC has its own limitations that were, and
>> remain, quite restrictive.
>
> Could they not just tap a single phase?

The problem wasn't getting a single phase supply, the problem was
driving a train with a single phase supply. Single phase AC is
challenging to do useful things with when it comes to motors.

Robin