Great Western Main Line electrification - ongoing discussion

[whole diary]

[Bmblbzzz]

Very interesting write up and photos.

As for a picture.....

Ah a blue hat ........... that tells a tale 

UN peacekeepers separating the armies of Offa and Tewdric? 

[TonyK]

UN peacekeepers separating the armies of Offa and Tewdric? 

Bloody Corbynistas getting in everywhere.

[onthecushions]

At last! The OLE^▸ (Overhead Line Equipment, more often "OHLE") fairy has blessed Reading station with some dangly bits. Though you might quibble that chunks of steel rigidly bolted on like those don't so much dangle as stick out awkwardly.

And aren't they awkward? Series One has been criticised for being so chunky, but that's mainly the supporting structures (portals, posts, and cantilevers). The OLE stuff that gets attached looks - well at least it looks like it was designed. This looks like whatever was around in the steelyard when the job needed to be done.

As I recall it, Reading was to be fitted out for OLE within RSAR, but the design work started before it was decided to electrify the GWML^▸ (Great Western Main Line) (or for Crossrail to come all the way). Series One was designed for the GW^» (Great Western - used as an abbreviation for the area / lines under the Great Western franchise, as opposed to FGW which includes "First", the company operating them too. For tickets - about), from 2011 to 2015.

I wonder what's going to fix onto the end of those skyhooks? I don't think Series One will fit. Perhaps Series two, or the design Furrer and Frey did for the GE (which must be similar to Series Two)?

Perhaps my artistic judgement isn't up to much but I think the appearance of the supports pictured is much better than the Series 1 plonked (illegally?) in the Goring Gap AONB^▸ (Area of Outstanding Natural Beauty)'s. The diagonal latticework is quite elegant - it's the same as BR^▸ (British Rail(ways)) Mark 1 I believe and must be a more efficient material design than the crude square cut-outs of NR^» (Network Rail - home page) Series 1. Also, the solid I sections at least meet at the ends rather than overlapping like temporary scaffolding. The various risers and droppers don't show so much in the distance and are at least functionally necessary. I do though wonder why the prominent ATF feed needs to be run above the portal as it has to drop down to troughers for bridges etc frequently. A neater solution would have been to run it at ground level like the 33kV feed for 750V dc substations.

OLE Nerd,

OTC

[Thatcham Crossing]

I've been for a ride into PAD^» (Paddington (London) - next trains) this morning from THA, and more and more OLE^▸ (Overhead Line Equipment, more often "OHLE") uprights are appearing on the B&H^▸ (Berks and Hants - railway line from Reading to Taunton via Westbury) (aside from between Theale and Reading where I only noted a couple).

What I also noticed is that some of the uprights look quite thin/lightweight in nature, and don't look like they would support the heavy lattice-type crossbeams that seem to predominate between RDG^▸ (Rail Delivery Group, or Reading station, depending on context) and PAD.

Does this mean that lighter-weight OHLE^▸ (Over-Head Line Equipment (electrification via catenary)) is being installed on the B&H?

[paul7575]

I do though wonder why the prominent ATF feed needs to be run above the portal as it has to drop down to troughers for bridges etc frequently. A neater solution would have been to run it at ground level like the 33kV feed for 750V dc substations.

Running a bare cable at a height will cost a small fraction of a replacement 25kV insulated cable to go into troughs.  AIUI^▸ ('as I understand it') the insulated cable has to have a greater cross-section for the same current, because it will not radiate heat into free air.

Paul

[John R]

Typically on double track lines there is no span across the whole width, with each track having completely independent structures.  So yes, they would be lighter, but it's completely normal.

[paul7575]

Typically on double track lines there is no span across the whole width, with each track having completely independent structures.  So yes, they would be lighter, but it's completely normal.

The top picture on page 4 of the Furrer and Frey Series 1 pamphlet (link below) shows the typical set up for a two track railway, they mention that they would use a twin track cantilever on one side if they needed to provide a gap for signal sighting.

http://www.furrerfrey.ch/dam/jcr:98f3522c-51ff-4d89-9fd7-dc16601d1db3/140918_F%20F_Series1_pamphlet_onlinePub.pdf

Paul

[Electric train]

I do though wonder why the prominent ATF feed needs to be run above the portal as it has to drop down to troughers for bridges etc frequently. A neater solution would have been to run it at ground level like the 33kV feed for 750V dc substations.

Running a bare cable at a height will cost a small fraction of a replacement 25kV insulated cable to go into troughs.  AIUI^▸ ('as I understand it') the insulated cable has to have a greater cross-section for the same current, because it will not radiate heat into free air.

Paul

As Pauls said.  The cable used for ground level is 400mm² has to be placed in troughing, general rule is at lease 1m from other cables all of which makes it an expensive option.  Also its screening effect is less effective when run as a cable.

[Oxonhutch]

The cable used for ground level is 400mm² has to be placed in [t]roughing...

So that is nearly an inch in diameter.  How thick is the insulation wrapped around that for a 25kV service?

Me thinks that this will become a mighty cable - worthy of its own trough!

[Thatcham Crossing]

Thanks to JohnR and Paul7755 for the explanations, supported by documentation. Guess I was forgetting that this is a 2 track railway (in the main) which will have independent structures over each side of it.

[chrisr_75]

There was a bi-lingual crew from BBC^» (British Broadcasting Corporation - home page) Wales so I suspect there will be something from them on screen later in the week.

This popped up this morning:

http://www.bbc.co.uk/news/uk-wales-south-east-wales-37553620

There could well be something related on the BBC Wales/S4C news this evening

[TonyK]

Intersting. I looked at the flights from Cardiff to London City - there are three daily, operated by Flybe. The aircraft is a Bombardier Dash 8 Q400. If you don't want the sparrowfart flight, you can do the return for under £100, with a journey time today of 33 minutes. The early (8.00am) plane costs £115 to LCY with hand luggage only, which seems rather competitive for the busy executive. Shame then that the flights are only for the duration of the tunnel closure.

Stats etc here on Flightradar24. I love the routing into London City - that is nothing unusual. I have seen flights from Dublin taken almost to France to fit in with the traffic. The approach from the east is almost the same as Heathrow.

[ChrisB]

I suispect that the margins on those prices wouldn't stand up for any length of time....

[TonyK]

I suispect that the margins on those prices wouldn't stand up for any length of time....

Possibly there is a contract with the Welsh government. Margins on aircraft are tiny compared to the capital cost of the kit. I once had the privilege of the jump seat in the cockpit of a 737 flying into Stanstead. After we landed, the pilot switched to ground power before shutting the engines down. He told me that cost £16 per hour, whereas running the auxilliary power unit cost £36 per hour. The turnround time was 40 minutes, and the difference in the two costs could be the difference between profit and loss on a flight.

If Flybe haven't anything else for a Dash 8 and a crew to do, this would seem a good idea in the long term, but I reckon they have put special measures into place, maybe cancelling a bit of leave and chartering an aircraft - although they own the one used on the flights yesterday.

[Surrey 455]

I suispect that the margins on those prices wouldn't stand up for any length of time....

Possibly there is a contract with the Welsh government. Margins on aircraft are tiny compared to the capital cost of the kit. I once had the privilege of the jump seat in the cockpit of a 737 flying into Stanstead. After we landed, the pilot switched to ground power before shutting the engines down. He told me that cost £16 per hour, whereas running the auxilliary power unit cost £36 per hour. The turnround time was 40 minutes, and the difference in the two costs could be the difference between profit and loss on a flight.

If Flybe haven't anything else for a Dash 8 and a crew to do, this would seem a good idea in the long term, but I reckon they have put special measures into place, maybe cancelling a bit of leave and chartering an aircraft - although they own the one used on the flights yesterday.

It's curious that an aircraft shuts it's engines down when stationery but an HST^▸ (High Speed Train (Inter City class 43 125 units)) (and sometimes 165/6) keep theirs running. Knowing that there are issues starting up an HST engine, I wonder what the financial cost of keeping those engines on are.