Chiltern Mainline Upgrades post TPE Mk5As

[D365]

However, everything running into Liverpool Street at a low level all day reduces conflicts and improves reliability. As you said, the non-core parts are the issue. Network Rail is currently working on upgrades like resignalling with ETCS and OLE improvements.

I’m not aware of any active ETCS resignalling programmes other than ECML (EDCP), Transpennine (TRU) or WCML (Trilink). Of which none apply to this thread.

 

[BerkshireRails]

I’m not aware of any active ETCS resignalling programmes other than ECML (EDCP), Transpennine (TRU) or WCML (Trilink). Of which none apply to this thread.

The Great Western Mainline between Ealing Broadway and Stockley Bridge Junction gained ETCS L2 to replace BR-APT on Heathrow Express and Elizabeth Line services.

 

[D365]

The Great Western Mainline between Ealing Broadway and Stockley Bridge Junction gained ETCS L2 to replace BR-APT on Heathrow Express and Elizabeth Line services.

Fair enough, but that is not relevant to Chiltern mainline operations.

 

[BerkshireRails]

Fair enough, but that is not relevant to Chiltern mainline operations.

It is as JonathanH said Elizabeth Line Shenfield is unreliable outside the Core and so shouldn't be extended to Aylesbury. I was just using ETCS on the GWML as an example of the upgrades Network Rail have been making for Elizabeth Line reliability improvement, in addition there is already 2tph of Shenfield to Heathrow T5 services.

 

[sad1e]

Neasden Junction to Sudbury Hill Harrow, South to West Ruislip, Denham, Gerrards Cross, Beaconsfield, High Wycombe, Princess, Bicester North and Hatton to Birmingham Moor Street, were all at one time four tracked. They had planned to join up Denham to the South to West Ruislip quadrack section which was never finished, in the 1930s.

They were never quad tracked , the station's were on loops , there is quite a big operational difference between the two.

However reinstalling the loops fully at station's like Sudbury hill Harrow , Northolt Park and South Ruislip would be advantageous as it would allow a metro like operation for inner suburban Chiltern stations , however it would require narrowing the Down platform at every platform the Loops have been removed at.

 

[Bald Rick]

If other platforms need extending, the BNP building has to go, to enable platforms 3-6 to be extended.

That building is worth something in the region of half a billion pounds.

 

[Railwaysceptic]

That building is worth something in the region of half a billion pounds.

You were correct to describe this thread as a fantasy and not a speculative thread. The idea that extremely valuable new buildings should be knocked down and that expensive 9-coach 345s should be sent up a non-electrified minor railway with mainly short platforms is bizarre.

 

[BerkshireRails]

You were correct to describe this thread as a fantasy and not a speculative thread. The idea that extremely valuable new buildings should be knocked down and that expensive 9-coach 345s should be sent up a non-electrified minor railway with mainly short platforms is bizarre.

The chiltern mainline would be electrified for the 345s and platform extensions would be the logical solution to short platforms.

However reinstalling the loops fully at station's like Sudbury hill Harrow , Northolt Park and South Ruislip would be advantageous as it would allow a metro like operation for inner suburban Chiltern stations , however it would require narrowing the Down platform at every platform the Loops have been removed at.

At Sudbury & Harrow Road it makes logical sense to move the platforms onto the outside of the alignment to enable the fast lines to be laid in the middle. At Sudbury Hill Harrow the platforms would need pushing back to fit four tracks. Then you can 2 mile long passing loop, or with some pushing you could get a 3 1/2 mile loop between Sudbury Tunnel and Neasden Junction, it would require new retaining walls and bridge spans.

 

[sad1e]

The chiltern mainline would be electrified for the 345s and platform extensions would be the logical solution to short platforms.

At Sudbury & Harrow Road it makes logical sense to move the platforms onto the outside of the alignment to enable the fast lines to be laid in the middle. At Sudbury Hill Harrow the platforms would need pushing back to fit four tracks.

That couldn't be done at Sudbury and Harrow road due to subsidence issues , it had side platforms until the early 90s , when they had to be removed due to subsidence of the land on the side and the poor condition of the platforms.

Sudbury and Harrow hill could easily have it's platforms knocked back to put t in loops however.

It would probably be more cost effective to close harrow road and upgrade harrow hill instead.

 

[NCT]

The chiltern mainline would be electrified for the 345s and platform extensions would be the logical solution to short platforms.

At Sudbury & Harrow Road it makes logical sense to move the platforms onto the outside of the alignment to enable the fast lines to be laid in the middle. At Sudbury Hill Harrow the platforms would need pushing back to fit four tracks. Then you can 2 mile long passing loop, or with some pushing you could get a 3 1/2 mile loop between Sudbury Tunnel and Neasden Junction, it would require new retaining walls and bridge spans.

You be on the phone to Rachel Reeves for it sure ain't gonna be the rest of us!

 

[BerkshireRails]

That couldn't be done at Sudbury and Harrow road due to subsidence issues , it had side platforms until the early 90s , when they had to be removed due to subsidence of the land on the side and the poor condition of the platforms.

Sudbury and Harrow hill could easily have it's platforms knocked back to put t in loops however.

It would probably be more cost effective to close harrow road and upgrade harrow hill instead.

Retaining walls would be used to combat the subsidence issues at Sudbury & Harrow Road. A well designed retaining wall can almost if not completely remove subsidence. Plus I wouldn't be surprised if British Rail did that to save money rather than fixing the embankment.

 

[BlueLeanie]

Whats underneath Marylebone?

There is the Bakerloo that runs beneath Melvombe Place, and I think the Jubilee sweeps under there somewhere, but is there potentially space for new electric platforms beneath the current platforms?

Does MYB have the vaults and multiple levels beneath it that the other major termini did when built?

 

[sad1e]

Retaining walls would be used to combat the subsidence issues at Sudbury & Harrow Road. A well designed retaining wall can almost if not completely remove subsidence. Plus I wouldn't be surprised if British Rail did that to save money rather than fixing the embankment.

BR probably did it for a good reason, a retaining wall on the embankment simply isn't worth the cost of the meagre passenger numbers the station gets.

 

[BerkshireRails]

BR probably did it for a good reason, a retaining wall on the embankment simply isn't worth the cost of the meagre passenger numbers the station gets.

The low passenger numbers are a symptom of insufficient capacity to run more stoppers, hence the 4 trains per day per direction service. Which leads to the cycle of managened decline.

 

[cle]

There is no demand there. It is low density, there is the tube and many work locally.

Best to close ‘Harrow Road’ and see if that enables anything. If not then the other one too.

 

[BerkshireRails]

There is no demand there. It is low density, there is the tube and many work locally.

Best to close ‘Harrow Road’ and see if that enables anything. If not then the other one too.

When I suggested closing Sudbury & Harrow Road that didn't go down well on this thread.

 

[Railwaysceptic]

There is no demand there. It is low density, there is the tube and many work locally.

That fundamental point is being wilfully ignored by many contributors to this thread.

== Doublepost prevention - post automatically merged: 17 Aug 2025 ==

The chiltern mainline would be electrified for the 345s and platform extensions would be the logical solution to short platforms.

Again, the numbers of passenger currently and the numbers potentially are far too low to justify electrification and platform lengthening.

 

[mr_jrt]

How are the numbers of potential passengers being determined? I don't have the data for current loadings to hand, but I would strongly suspect that were North Acton-High Wycombe/Princes Risborough/Aylesbury to gain a fast direct and frequent Crossrail service through to central London, demand and density would absolutely shoot up.

As a side point, it still boggles the mind how platform extensions can be so expensive they cannot be countenanced in many cases. I get that sometimes there are expensive obstructions at both ends, or signalling alterations that would be needed (particularly at a terminus), but seriously, in many cases it's just a glorified lump of concrete, and if the stopping positions and the track aren't changing, then it's little more than that. How they end up costing so much defies belief. In the days of old, I suspect you'd get weather-treated wooden extensions thrown up over a weekend to test longer services for a couple of years before more permanent structures would be put in place if things worked out...

 

[BerkshireRails]

How are the numbers of potential passengers being determined? I don't have the data for current loadings to hand, but I would strongly suspect that were North Acton-High Wycombe/Princes Risborough/Aylesbury to gain a fast direct and frequent Crossrail service through to central London, demand and density would absolutely shoot up.

As a side point, it still boggles the mind how platform extensions can be so expensive they cannot be countenanced in many cases. I get that sometimes there are expensive obstructions at both ends, or signalling alterations that would be needed (particularly at a terminus), but seriously, in many cases it's just a glorified lump of concrete, and if the stopping positions and the track aren't changing, then it's little more than that. How they end up costing so much defies belief. In the days of old, I suspect you'd get weather-treated wooden extensions thrown up over a weekend to test longer services for a couple of years before more permanent structures would be put in place if things worked out...

Based on cost for Leeds platform 17 extension being around £1 million for 20 metres I think this is a good estimate for cost to extend all platforms to be able to fit 9 cars of 345s rather than 6 cars at the shortest platform.

 

[brad465]

The latest RAIL magazine issue has a spread article about Chiltern looking at discontinuous electrification as part of its 2030 vision, based on Richard Allan's (Chiltern Managing Director) speaking at the Mk5 launch event. Final specifics haven't been confirmed, but currently include Marylebone station, then High Wycombe-Banbury/Oxford, with something possibly south of Birmingham Snow Hill as well.

 

[The Planner]

The latest RAIL magazine issue has a spread article about Chiltern looking at discontinuous electrification as part of its 2030 vision, based on Richard Allan's (Chiltern Managing Director) speaking at the Mk5 launch event. Final specifics haven't been confirmed, but currently include Marylebone station, then High Wycombe-Banbury/Oxford, with something possibly south of Birmingham Snow Hill as well.

That is the opposite to what I have heard. Neasden/South Ruislip to Wycombe with nothing else

 

[Class15]

That is the opposite to what I have heard. Neasden/South Ruislip to Wycombe with nothing else

I would personally do:

Marylebone
Finchley Road - Harrow-on-the-Hill/Ruislip
Wycombe - Banbury/Oxford
Birmingham Moor St

 

[brad465]

That is the opposite to what I have heard. Neasden/South Ruislip to Wycombe with nothing else

This is the relevant article text:

Speaking at the Mk 5A launch event, Chiltern Managing Director Richard Allan said precise locations had not been finalised, but noted: "We think Marylebone station, north of High Wycombe, and then wiring potentially towards Oxford or Banbury, and then look at new trains, infrastructure and power supply. We've done the Strategic Business Case. We now need to move to the Outline Business Case. As part of that, we want to go and talk to train manufacturers and say, 'can you provide a price for a package for power supply, infrastructure and trains to achieve an outcome that we will specify.'"

Electrification south from Snow Hill is also a possibility. Reiterating that final locations are yet to be decided, Allan added that "relatively small" amounts of electrification would be enough to bring in battery-electric trains.

 

[SynthD]

Towards Banbury and Oxford sounds like it would end at Aynho and New North junctions respectively, avoiding disruption to the XC route.

 

[Zomboid]

Given the likelihood of XC acquiring bi-modes of some sort in the medium term, Aynho to Leamington would seem like an ideal section to look at electrifying first.

Combine with Didcot to Bletchley and something like Wycombe to Ruislip and there's a decent amount to keep batteries topped up for Chiltern and XC, allow GWR to serve Oxford with EMUs, and some relatively small sections to infill for completing Didcot to Coventry.

Not sure what the answer for Aylesbury would be, maybe wiring Marylebone plus upgrading the Metropolitan line supplies to allow the trains to charge on DC as well. And something might be needed in Birmingham, too. Tyseley to Moor St could ultimately benefit WMT as well.

 

[Crosslinker]

That building is worth something in the region of half a billion pounds.

Network Rail looked at this as a possible option in the West Midlands & Chilterns Route Study 2017: "Further work has been undertaken to identify the scope and scale of works associated with the wider redevelopment of Marylebone station required to accomodate forecast passenger demand. This option would provide additional platforms and associated passenger facilities for the operation of additional trains. However, this would include the acquisition of additional land, not currently within the ownership of the rail industry. A high level assessment has indicated this would cost in excess of £700m." See Network Rail West Midlands & Chilterns Route Study 2017 - Page 80.

It looks like the preference is to route a number of services to Chiltern platforms at Old Oak Common - See Network Rail - Chiltern and East West Strategy Summary 2025

 

[MattRat]

Given the likelihood of XC acquiring bi-modes of some sort in the medium term, Aynho to Leamington would seem like an ideal section to look at electrifying first.

The DaFT and Treasury wouldn't even let them spend the money to get all the available Voyagers from Avanti. What makes you think they'd open the purse for bi modes? Especially since XC don't serve London, which puts them down the pecking order in the eyes of the DaFT and Treasury.

Building on from that, any true upgrades to services will likely come from TFL, so Metropolitan or Elizabeth line services as others have mentioned. They still have to get funding, but there is much more political will to actually spend any funding they have or get