I am an electrification Engineer to us a buffer section is a section of electrification traction power contact system that is bonded to the traction return system ........... for OLE section of the contact wire (typically a wire run) is Earthed by a cable bolted to the contact wire and Earthed structure for Third rail the conrail has a cable bolted to the conrail and to the traction return rail typically the section is longer than the length of the normal train set in the area.

The purpose of the buffer section is to allow for the equipment under construction past it not to be "under rules" ie permits to work are not required to work on it, usually a stage is reached where the construction area is declared as under rules but has yet to be energised this is to provide a safety margin for the construction teams.

On a progress point I noticed Monday that there are still wire runs to be completed in Acton Yard, whis also means there are still registration, hights and stager checks to be done and the final step is section proving

 

In what context is the word 'buffer' used here please? Rail dead-end siding or electrical?

 
This is the official version of the "narrative" in the "Enhancements Delivery Plan England and Wales / Entry Into Service (EIS) schedule / September 2025". That document is in this page. Of course, quite what the status of that "narrative" is, and how it relates to be the justification that was accepted by the funders, is hard to tell if you weren't in the room.

 

Stuving is correct, the Acton Wells branch electrification was discussed at the time of construction of HEX in 1996 as a possible Freight into Acton Yard, the FOC's principally EWS did not want to fund it as the CEO of EWS was heavily invested in diesel locomotives.  BAA did consider it as a potential future option for a Heathrow - St Pancras service to link to the proposed HS1 and Eurostar.

The prime mover today I suspect is the GWR diversions into Euston over the Christmas Paddington blockades for the next few years, also the attitude of the FOCs has changed with the move to de-carbonise their operation which has been made easier in the way that Network Rail is now allowed to charge for electrified track access

 

I do not know when the Yard will be done, I would guess when the next weekend Isolation of the Reliefs is planned; final connections to done, any buffer sections having permeant Earths removed and then the section proving.

 
For those who missed the action over the last 2 nights, you will be glad to know that it is running again tonight (2/10/2025) and tomorrow (3/10/2025).
This time it is using 99001, 99002 and 69010

Timings are
Thursday https://www.realtimetrains.co.uk/service/gb-nr:R15439/2025-10-02/detailed#allox_id=0
Friday https://www.realtimetrains.co.uk/service/gb-nr:R15478/2025-10-03/detailed

To give you an idea of the timings it is passing through Didcot on the outward service at 23:32 tonight and on the return 20:51 tomorrow.

 
Once energised could in theory get from Cardiff via Acton to Dunblane/Alloa on electric.

Or as far east as Ipswich/Norwich/Harwich (but not Felixstowe)

Not sure if it's possible to join HS1 (without a reversal) on 25kv and (if traction type was allowed) continue through Channel tunnel.

I think there are gaps in 25kv so can't go beyond Cardiff towards the Welsh valleys.  And cannot take Mendip stone on electric as 25kv ends at Newbury.  But maybe in a few years it might be possible.

 
Photos show the two class 99s at Newport both with pantographs up

 

If by that you mean why was it not decided to do it earlier, I think that's due to the process for funding decisions. Filling in electric gaps for goods use of for some unspecified future diversion does not have a budget held by someone who would sign off the work. And that isn't why it's being done now.

The justification that got the work signed off is to allow 345s to get from the western side of the Old Oak blockades to and from Ilford for R&R. (So I guess that means it's probably HS2 money that's paying for it.) That is first required in December 2026, and it's on schedule to be ready for that (so it's not late in that sense).

 

I am surprised this short non-electrified link has taken so long TBH. Was it the tight clearances of the road over bridge near the bottom of the bank that held it up?

 

Quite common when testing new traction, to have a backup locomotive (or 2) because if you are seeing if it can pull train up hills etc, and it doesn't, then have a problem.  Much easier to then fire up the extra loco and move it.

Surprised that all the wagons were empty, as normally trying to confirm it can meet the theoretical timings for heavy loads.  Often the tests are run few percent over 100% normal weight to give some margin in case not all locos in a batch are exactly same performance

 

Yes, indeed.

I think the Class 99s will be a big success story with their much beefier diesel engines than the earlier Class 88s.  There's also the 'tri-mode' Class 93s very much on the horizon as well.  Both types could well be seen on the GWML when this electrification is completed.

First of two sections to be energised is from Acton Wells Junction to a neutral section near the bottom of the bank from 3rd November, with the remaining bit through Acton Yard to follow.  Do you know when that's scheduled for 'Electric train'?

 

With the Acton - Wells branch (Acton Yard to Acton Wells Jcn) being electrified I feel electric hauled fright will be a more common sight on the GWML

 
There seemed to be a class 66 as a back up. Three locomotives seems over the top although in fairness it what was a long train of empty wagons.

 
The first electrically hauled freight train on the GWML ran last night (30/9/2025) using the new bi-mode class 99's owned by GBRF

It worked from Wellingborough on the MML to Acton then down the GWML to Pengam https://www.realtimetrains.co.uk/service/gb-nr:R15444/2025-09-30/detailed#allox_id=0

For those who didn't see it last night, the return journey is today and slightly earlier than last night's journey https://www.realtimetrains.co.uk/service/gb-nr:R15441/2025-10-01/detailed

There are various videos available on YouTube including this one taken at 23:30 at Didcot Parkway https://www.youtube.com/watch?v=SeV03cGosOs.

Let's hope this the first of many.