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Author Topic: Great Western Main Line electrification - ongoing discussion  (Read 103227 times)
Adrian
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« Reply #840 on: August 12, 2019, 08:29:46 pm »

There is also the question of why a whole class of emus seemed to have a problem re-starting after the power came back on again.  Fitting trains with a backup battery or diesel engine might not help if they shut down and need a technician to come a couple of hours later to persuade them to work again.  I think there was a suggestion that it was the drop in AC frequency that tripped the trains' systems out?

National Grid were saying that they need to consider carefully about what to disconnect to minimise disruption - but when a main railway line presents such a variable and asymmetric load on the grid, is it not one of the first they would choose to shed when trying to stabilise the supply?
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broadgage
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« Reply #841 on: August 12, 2019, 09:07:31 pm »

AFAIK it was the new Thameslink EMUs that could not be re-started after the failure without an engineer.
Some reports suggest that these units trip out on low line frequency so as to prevent the potential generation of harmonics that might interfere with the signalling.
The traction package was probably only tested over a narrow range of line frequency, and then someone decided that "you cant have too much safety" and that everything should stop if the line frequency was outside of the limit.

Although other electric trains work without this feature, it might be a struggle to convince the health and safety industry that this "safety feature" can be removed.
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A proper intercity train has a minimum of 8 coaches, gangwayed throughout, with first at one end, and a full sized buffet car between first and standard.
It has space for cycles, surfboards,luggage etc.
A 5 car DMU is not a proper inter-city train. The 5+5 and 9 car DMUs are almost as bad.
TonyK
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« Reply #842 on: August 12, 2019, 09:31:20 pm »

They were also a great aid to visual navigation when I used to fly in the local area. Could be seen from 30-40 miles away in all directions when visibility was good.

For me as well. It was particularly useful because of everything around it that needed special treatment by the private pilot, such as RAF Lyneham and Benson, Harwell nuclear research facility, now no longer prohibited airspace, and the run into the airspace minefield that is London. Some landmarks don't look so big from the air - flying to Dunkeswell for the first time, my instructor told me to turn south over the Wellington monument, and I was 7 or 8 minutes away, but I never saw the monument, relying on the turning triangle for the WSR to check position. As TC says, though, the Didcot towers were a very easy spot on a clear day, certainly from 2500 feet, east of Bath.

Decontamination will be a big job. The small purifier house at the old Canons marsh gas works in Bristol took ages - but that was Bristol. Even given the closer proximity to London, it won't be a quick job to start building on a former power station AND ordnance factory.
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ellendune
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« Reply #843 on: August 12, 2019, 09:40:58 pm »

Decontamination will be a big job. The small purifier house at the old Canons marsh gas works in Bristol took ages - but that was Bristol. Even given the closer proximity to London, it won't be a quick job to start building on a former power station AND ordnance factory.

I am not sure, gas works sites are renowned for being some of the most contaminated around.  When it was used for car storage you may have noticed that not many weeds grew on the old Acton Gas Works site!
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TonyK
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« Reply #844 on: August 12, 2019, 09:50:18 pm »

Decontamination will be a big job. The small purifier house at the old Canons marsh gas works in Bristol took ages - but that was Bristol. Even given the closer proximity to London, it won't be a quick job to start building on a former power station AND ordnance factory.

I am not sure, gas works sites are renowned for being some of the most contaminated around.  When it was used for car storage you may have noticed that not many weeds grew on the old Acton Gas Works site!

Reading up, I see your point now. The towers themselves were used only for cooling excess hot water, so shouldn't be so bad. I should think remediation, to use the posh term, is still likely to be a big job, though, given our modern standards.
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didcotdean
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« Reply #845 on: August 12, 2019, 10:02:45 pm »

It was an ordnance depot rather than a factory, although I speculated earlier that you can never be sure what is on a brown field site. Having used the overlay facility of old and modern maps at the National Library of Scotland shows that actually quite a bit of the power station site earlier was not built on but was a recreation ground. There were several ranks of buildings on the southern edge each flanked by railway sidings on both sides, ultimately connected to the West Curve.
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Thatcham Crossing
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« Reply #846 on: August 13, 2019, 08:14:16 am »

Quote
It was an ordnance depot rather than a factory

....as was the depot in Thatcham (just west of the Station) that is now a housing estate.
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Electric train
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« Reply #847 on: August 13, 2019, 05:14:53 pm »

Decontamination will be a big job. The small purifier house at the old Canons marsh gas works in Bristol took ages - but that was Bristol. Even given the closer proximity to London, it won't be a quick job to start building on a former power station AND ordnance factory.

I am not sure, gas works sites are renowned for being some of the most contaminated around.  When it was used for car storage you may have noticed that not many weeds grew on the old Acton Gas Works site!

Reading up, I see your point now. The towers themselves were used only for cooling excess hot water, so shouldn't be so bad. I should think remediation, to use the posh term, is still likely to be a big job, though, given our modern standards.

Don't forget there was a vast quantity of coal used and stored on the site, plus all the ash all of which needs decontamination.

The towers would become a liability, I doubt future owners of the site, local authorities, English Heritage would want take them on and the current own has no business case to continue with the lability
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« Reply #848 on: August 30, 2019, 11:47:46 am »

Reported elsewhere that from September 15th IETs will be able to pass through Steventon on electric at a limit of 110mph so will no longer need to switch to diesel at Didcot or Wantage Road. Not sure if 387s to/from Swindon will still be limited to 60mph.

Apparently Network Rail plan to lower the wire height over Stocks Lane crossing and will impose a height restriction on the road which will allow full 125mph running some time next year.

Reading the minutes of Steventon Parish Council on their meeting with Network Rail it appears unlikely that the High Street bridge will now need to be demolished.

(I do wonder why all this wasn't worked out years ago!)
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« Reply #849 on: August 31, 2019, 07:10:08 am »

Reported elsewhere that from September 15th IETs will be able to pass through Steventon on electric at a limit of 110mph so will no longer need to switch to diesel at Didcot or Wantage Road. Not sure if 387s to/from Swindon will still be limited to 60mph.

Apparently Network Rail plan to lower the wire height over Stocks Lane crossing and will impose a height restriction on the road which will allow full 125mph running some time next year.

Reading the minutes of Steventon Parish Council on their meeting with Network Rail it appears unlikely that the High Street bridge will now need to be demolished.

(I do wonder why all this wasn't worked out years ago!)

The directive from the DfT was for the electrification to be fully TSI compliant for 140 mph running and reduced level of maintenance compared to Mk3.

This posed a problem at Steventon a low road over bridge closely followed by the 2 level crossing the wire heights did not work out the solution driven by the above was to replace the bridge.  It has taken the project team a lot of testing, design changes and I suspect many long meetings with DfT to convince them to compromise on their original spec
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Mark Carne 26 June 2015 - "The challenges of delivering myriad improvement projects while still running a railway seven days a week were simply overwhelming".
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« Reply #850 on: September 01, 2019, 02:09:44 pm »

I will be interested to see how they will enforce the vehicle height restriction.  A wire-strike or flash-over with 25kV OHL is somewhat more serious than a simple bridge strike.
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stuving
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« Reply #851 on: September 01, 2019, 02:46:36 pm »

I will be interested to see how they will enforce the vehicle height restriction.  A wire-strike or flash-over with 25kV OHL is somewhat more serious than a simple bridge strike.

According to the ORR's "Level Crossings: A guide for managers, designers and operators", you do this:

Quote
Related to electrified lines

2.305 Where the railway is electrified with overhead conductors, signs to Diagram 779 should be provided with an appropriate plate (Diagram 780A). At user worked crossings, suitable signs warning of the danger from bare electrical conductors such as ‘Danger, overhead live wires’ should be provided and face towards the user approaching the decision point.

2.306 Overhead conductors at level crossings should be at the greatest height practicable. Signs to Diagram 780A should show a safe height which allows for suitable safe clearance under the overhead conductors.

2.307 Where currently overhead conductors at level crossings are not at maximum practicable height, steps should be taken to remedy this situation, so far as is reasonably practicable. In the interim, signs to Diagrams 779 and 780A should be provided at the last available alternative route before the crossing.

2.308 At any crossing where, currently, overhead conductors are not at the maximum practicable height, a height gauge to Diagram 781 should be erected at the ‘safe height’. Signs to Diagram 780.2A should show a safe height which allows for suitable safe clearance under the overhead conductors. At user worked crossings suitable warning signs should be displayed.

2.309 In calculating the ‘safe height’, allowance should be made for the effect of the vertical profile of the carriageway on a road vehicle and its load.

2.310 At crossings where the gradient of the approaches is such that vehicles with large overhangs or conveying a large overhanging load could touch or come dangerously close to the overhead line equipment, even though they are lower than the ‘safe height’ shown on the sign to Diagram 780A or 780.2A, an additional sign depicting the hazard, such as ‘Danger, overhanging load may foul live wires’ should also be provided.
(I'm sure you can guess what the signs referred to are. )

Now, is blowing up that bridge suddenly at night when no-one is expecting it "reasonably practicable"?

But anyway, I'd prefer to see a chunky steel portal.
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SandTEngineer
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« Reply #852 on: September 01, 2019, 03:39:07 pm »

The Bath problem (and a few other similar places).  Now, after the end of October, when we can choose to no longer comply with TSIs (well, isn't that what B****T is supposed to be about) how about this: Yesterday I was travelling under/looking at the tramway style of 25kV electrification leading into the Depot at Soho in Birmingham.  It appears to use a single wire (so not actually catenary) and simple MK1 structures (quite slim and unobtrusive).  If view of the low speeds and the fact most trains stop at Bath, why not use it there?  Now where is ET when you need him Wink
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Noggin
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« Reply #853 on: September 01, 2019, 09:43:45 pm »

The Bath problem (and a few other similar places).  Now, after the end of October, when we can choose to no longer comply with TSIs (well, isn't that what B****T is supposed to be about) how about this: Yesterday I was travelling under/looking at the tramway style of 25kV electrification leading into the Depot at Soho in Birmingham.  It appears to use a single wire (so not actually catenary) and simple MK1 structures (quite slim and unobtrusive).  If view of the low speeds and the fact most trains stop at Bath, why not use it there?  Now where is ET when you need him Wink

Does https://twitter.com/25kV/ ever visit here? Quite literally wrote the book on OHLE.

But if you look at this pic from Durham you can see that it's certainly possible to have something very visually unobtrusive without resorting to extreme measures. 





 
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IndustryInsider
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« Reply #854 on: September 02, 2019, 10:07:02 am »

But if you look at this pic from Durham you can see that it's certainly possible to have something very visually unobtrusive without resorting to extreme measures.

As long as you don’t mind it all getting blown down when the wind picks up...  Wink
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To view my GWML Electrification cab video 'before and after' video comparison, as well as other videos of the new layout at Reading and 'before and after' comparisons of the Cotswold Line Redoubling scheme, see: http://www.dailymotion.com/user/IndustryInsider/
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