125mph Chiltern Mainline - Possible?

[ChilternHenry]

A compulsory land purchase i'm sure could be made in the case of Haddenham & Thame Pway, especially if its only a few houses. Although i know loop lines at stations would undoubtedly increase capacity, if there is a fast train behind a slow entering the loop line to the platform of a station, and the fast is reasonably close to the slow service ahead, how much time would the fast services loose by being checked by an amber or yellow signal due to the slow entering the loop? I'd say it could actually be a significant amount of time if it were to happen more than once a journey. If you want to run high frequency services, 4 lines are definitely needed, but to what extent is a high frequency service actually needed between London and High Wycombe. You could get away with 2tph at Beaconsfield and Gerrards Cross, 2/1tph at Denham and both Ruislip stations, and the others need 1tph or less, there doesn't actually seem to be much demand for other stations, apart from Wembley when an event is on. I'd argue a high frequency service isn't needed, and that you could get away with the following service pattern, feel free to alter, or point out inaccuracies. I should point out this would be an inspirational service pattern:

1tph Marylabone - Ayelsbury Vale Pway calling Wembley Stadium, Sudbury Hill Harrow, Northolt Park, West Ruislip, Denham, Gerrards Cross, Beaconsfield, High Wycombe, Saunderton, Princes Risborough, Monks Risborough, Little Kimble, Ayelsbury and Ayelsbury Vale Pway.

1tp2h all stations to HW.

1tph Marylabone - Oxford calling at High Wycombe, Biscester Town, Water Eaton Pway, Oxford.

1tp2h Marylabone - Oxford calling at Gerrards Cross, Beaconsfield, High Wycombe, Princes Risborugh, Haddenham & Thame Pway, Biscester Town, Islip, Water Eaton Pway, Oxford.

1tp2h Marylaybone - Banbury calling at Gerrards Cross, Beaconsfield, High Wycombe, Princes Risborough, Haddenham & Thame Pway, Biscester North, Banbury

1tph Marylabone - Birmingham Moor Street calling at (High Wycombe in peaks), Banbury, Warrick/Warrick Pway, Solihull, Moor Street.

1tph Marylabone - Birmingham Snow Hill (extending to Kidderminster in peaks) calling at High Wycombe, Haddenham & Thame Pway, Biscester North, Banbury, Leamington Spa, Warrick, Warrick Pway, Dorridge, Solihull, Olton, Acocks Green, Moor Street, Snow Hill.

That's 6 Trains Per Hour. More trains may be added in the peak, and stopping patterns may vary. Fasts are to be timetabled to leave immediately infront of slows, so they dont catch up with a possible slow train ahead that cant be put into a loop or 4 track section to be overtaken.

 

[corfield]

Swtpassenger So if you dont like the presence of the brick bridge it can be vanished & assumed away?
You should run the railways as I'm sure your approach would be cheap and effective.

It's actually a pretty substantial bridge/mini viaduct, not to mention the rest of the deep cutting (2 track width) with expansive and expensive properties along the top.

Still no evidence the tunnel is actually 4 track capable. And ref internet research - dont apply your standards to others. I've never found or seen anything authoritative regarding what has actually been built hence asking as someone else may. This seems a logical forum to hope there is someone better informed.

I'd suggest overall that 4 tracking around GX isnt a likely option.

Some passing loops reinstatement plus more track in Ruislip area is about the limit unless the vast HS2 funds were reallocated for a rebuilt vs new line (which Id disagree with as HS2 is a much better idea and use of the resources than a CML++). I agree a high intensity service to H.Wyc is OTT but I had thought the ideas for such a Metro service were more focussed closer to London anyway (Ruislip and the other inner stations). Although the Denham-H.Wycombe corridor is already busy (standing off peak today).

I personally would like to see the West Hampstead Interchange developed further as it would offset the poor connections at Marylebone and make for vastly easier access to North London without the time/hassle of going in and out via the centre. A connection to the WLL route would also be nice to be able to get down to South/West London areas similarly.

If the High Wycombe-Ruislip services (ie stopping in that section) were diverted down the New North Line as part of Crossrail as originally intended - could Marylebone handle the remaining CML and take the entire Lond-Aylesbury line services ?

 

[Cherry_Picker]

1tp2h all stations to HW.

1tph Marylabone - Oxford calling at High Wycombe, Biscester Town, Water Eaton Pway, Oxford.

1tp2h Marylabone - Oxford calling at Gerrards Cross, Beaconsfield, High Wycombe, Princes Risborugh, Haddenham & Thame Pway, Biscester Town, Islip, Water Eaton Pway, Oxford.

1tp2h Marylaybone - Banbury calling at Gerrards Cross, Beaconsfield, High Wycombe, Princes Risborough, Haddenham & Thame Pway, Biscester North, Banbury

1tph Marylabone - Birmingham Moor Street calling at (High Wycombe in peaks), Banbury, Warrick/Warrick Pway, Solihull, Moor Street.

1tph Marylabone - Birmingham Snow Hill (extending to Kidderminster in peaks) calling at High Wycombe, Haddenham & Thame Pway, Biscester North, Banbury, Leamington Spa, Warrick, Warrick Pway, Dorridge, Solihull, Olton, Acocks Green, Moor Street, Snow Hill.

That's 6 Trains Per Hour. More trains may be added in the peak, and stopping patterns may vary. Fasts are to be timetabled to leave immediately infront of slows, so they dont catch up with a possible slow train ahead that cant be put into a loop or 4 track section to be overtaken.

With due respect, that is bonkers.

 

[ChilternHenry]

With due respect, that is bonkers.

I admit, its not perfect, probably overlooked a few things, but tell me where i'm bonkers rather than saying it is just bonkers. With investment, I don't see why the line could not handle 6tph in each direction.

 

[Clip]

To start with haddenham, its not do much the compulsory purchase of the land going through there its the before and after too, just how far back do you go so you keep a decent embankment ttoo and how much will that cost!

Quick glance at your diagrams and there's no need for a stopper to Oxford, keep people changing a hwy IMO,

 

[RPM]

As Cherry Picker has already said, replacement of the 75mph class 165 fleet would bring about immediate speed improvements without additional infrastructure work. I can certainly see this happening within the next decade.
In terms of four tracking, the vast majority of overbridges between Northolt and Ashendon are already four track width but the underbridges are not, except for the River Colne viaduct at Denham. Gerrards Cross tunnel is a very generous four track width plus sufficient height for electrification.
--- old post above --- --- new post below ---
You also need to consider what the rolling stock is capable of. 168s are fairly underpowered. On the up road the line speed changes to 100 by Wembley depot but you don't reach 100 until Northolt Junction. Similarly once you pass Denham and the gradient starts to rise your speeds starts dropping off even under full power. By Gerrards Cross it is normally down to at least 95. A 125 line speed would be largely irrelevant.

 

[cle]

As Cherry Picker has already said, replacement of the 75mph class 165 fleet would bring about immediate speed improvements without additional infrastructure work. I can certainly see this happening within the next decade.
In terms of four tracking, the vast majority of overbridges between Northolt and Ashendon are already four track width but the underbridges are not, except for the River Colne viaduct at Denham. Gerrards Cross tunnel is a very generous four track width plus sufficient height for electrification.
--- old post above --- --- new post below ---
You also need to consider what the rolling stock is capable of. 168s are fairly underpowered. On the up road the line speed changes to 100 by Wembley depot but you don't reach 100 until Northolt Junction. Similarly once you pass Denham and the gradient starts to rise your speeds starts dropping off even under full power. By Gerrards Cross it is normally down to at least 95. A 125 line speed would be largely irrelevant.

165s could go to replace pacers somewhere - or at least could go on the Amersham branch. But they shouldn't run on the mainline any more.

 

[swt_passenger]

Swtpassenger So if you dont like the presence of the brick bridge it can be vanished & assumed away?

I didn't say that did I? Widening bridges from 2 to 4 track is not a difficult problem. Do you recall the Trent Valley four tracking? 30 odd bridges were widened, and so were a few miles of cutting - the latter was done generally within the railway boundary by altering the cutting face angle.

Altering overbridges to allow for gauge clearance is also a commonplace matter, they have done a significant number in recent years and this is ongoing for the GW electrification. Timescales vary but the main structure is usually replaced in only a few weeks - removal and replacement of underground utilities normally cause the longest closures.

It's actually a pretty substantial bridge/mini viaduct, not to mention the rest of the deep cutting (2 track width) with expansive and expensive properties along the top.

Another poster has just suggested that the overbridges are already wide enough for four track, and he also points out that the Tesco Tunnel is a 'generous four track' size...

This latter point also appears pretty clear from a website dedicated to the saga of the Gerrards Cross tunnel collapse, a number of photos show how massive the span is compared to the DMU passing through, and as far as I can make out it is wider than the four track arch at the station end of the site:

Edit cos I forgot to paste the URL... http://www.meadwaypark.co.uk/TescoTunnel/

So maybe if the main arch at Marsham Lane is the same design as the (now partially hidden) Packhorse Rd bridge, most of your Gerrards Cross issues are solved...

 

[joeykins82]

Presumably following the GWML & Thames Valley branch electrification the 165/1 and 166 fleet might be cascaded to Chiltern which would at least give them 90mph until such time as electrification finally happens.

 

[kylemore]

There hasn't been much discussion of why people travel Chiltern as opposed to VT.

A very successful "Niche" market has been built up where there was little or none before and it is now a very big "Niche" indeed.

Would spending £100ms on infrastructure improvements to approach VT WCML timings be the best use of available funds especially with HS2 in the offing?

I'm not an expert in this area but I would suggest that people are attracted by a combination of keenly priced fares, customer service and connections not available when travelling WCML and an extra 20mins or so is neither here nor there to these travellers.

Steady but well thought out incremental improvements to journey times with fairly modest infrastructure projects and the removal of the slower stock (as suggested by the driver above) I feel would be more sensible than "Big Bang" developments.

Keeping the prices keen by steadily adding extra cars to trains in order to keep unit costs down or even reduce them and a concentration on customer service is I reckon more important than knocking say 15 mins off journey times which would have to be paid for by increased fares.

 

[HSTEd]

Longer trains run into problems with stabling of stock and the platform capacity at Marylebone unfortunately.

If the NMML was not being pulled up for HS2 you might be able to run into Paddington once Crossrail takes away all the suburbans though....

 

[swt_passenger]

Presumably following the GWML & Thames Valley branch electrification the 165/1 and 166 fleet might be cascaded to Chiltern which would at least give them 90mph until such time as electrification finally happens.

The FGW DMU fleet is usually considered to be transferring to the Bristol area though, this has been fairly consistently proposed by DfT across a number of documents over the last few years...