How long will the Class 158 & 159 soldier on for?

[dk1]

Both the 158/9 and the 166s which came soon after were built as 90mph stock. Was there a reason why this top speed was chosen, rather than 100mph, which was standard for "express" EMUs like the 317s etc by that stage?

Not sure whether it was so much the case then but I was told that there is a lot of difference between a 90mph railway and a 100mph one cost wise.

 

[Zomboid]

Indeed. It's a shame the recession of the early 1990s forced Regional Railways to divest what should have been 158873-158894 to NSE.

Not for users of the SWML, they've given really good service over the years (at least until SWR, I haven't followed it since then).

Though what might have happened if the 158s hadn't been diverted is a whole other thread of speculation which may have been better or worse.

== Doublepost prevention - post automatically merged: 5 Oct 2025 ==

sure whether it was so much the case then but I was told that there is a lot of difference between a 90mph railway and a 100mph one cost wise.

That's not a rolling stock thing though, there's plenty of places where 100 could have been exploited by 158/9s if they'd been capable.

Might have meant that 400hp was required rather than 350 though, with implications for maintenance and fuel consumption.

 

[The exile]

The 158/159 fleet were not a great design and were conceived at a time when the Provincial Sector were trying to raise the quality of its long-distance operation while trying to cut costs. They've done a job they've had to do on the Regional Routes but that work has gone and they are coming to the end of their natural service life.

Some of that work has gone. They are about to make a return to one of their original routes (Portsmouth - Cardiff).

 

[dk1]

Not for users of the SWML, they've given really good service over the years (at least until SWR, I haven't followed it since then).

Though what might have happened if the 158s hadn't been diverted is a whole other thread of speculation which may have been better or worse.

== Doublepost prevention - post automatically merged: 5 Oct 2025 ==


That's not a rolling stock thing though, there's plenty of places where 100 could have been exploited by 158/9s if they'd been capable.

Might have meant that 400hp was required rather than 350 though, with implications for maintenance and fuel consumption.

I can only presume it was the optimum speed to achieve the required acceleration as well as the higher speed for longer distance services above the 75mph which was more commonplace in the first batch of second generation DMUs.

 

[KevinBrum12]

Not for users of the SWML, they've given really good service over the years (at least until SWR, I haven't followed it since then).

Though what might have happened if the 158s hadn't been diverted is a whole other thread of speculation which may have been better or worse.

Almost certainly if the SWML had not received the 159's when they did it would have made life a heck of a lot more difficult for the nascent South West Trains. SWT at the time already had the challenge along with SouthCentral and SouthEastern of eliminating the BR Mark 1 based third rail units and having another fleet replacement on top may have made SWT more difficult to let.

Regional Railways did pick up some of the MKii stock from Waterloo - Exeter and it ended up operating the North Wales services through the privatisation with Class 37/4's (which gave reliable service) until First North Western took over and the class 175's arrived.

 

[Brubulus]

Almost certainly if the SWML had not received the 159's when they did it would have made life a heck of a lot more difficult for the nascent South West Trains. SWT at the time already had the challenge along with SouthCentral and SouthEastern of eliminating the BR Mark 1 based third rail units and having another fleet replacement on top may have made SWT more difficult to let.

Regional Railways did pick up some of the MKii stock from Waterloo - Exeter and it ended up operating the North Wales services through the privatisation with Class 37/4's (which gave reliable service) until First North Western took over and the class 175's arrived.

Wouldn't NSE have simply ordered more Networkers and Waterloo-Exeter would likely have been operated with 166s?

 

[Zomboid]

I think there was a proposal for a specific type of 16x based unit as an alternative, though it might have needed cab end gangways, so wouldn't have been a straight 166. Electrification and some type of HST were also on the table IIRC.

But 159s have ended up serving the route very well, and as a passenger don't feel anything like as decrepit as the slightly older 150/156s did last time I used them.

 

[KevinBrum12]

Wouldn't NSE have simply ordered more Networkers and Waterloo-Exeter would likely have been operated with 166s?

They'd have to have got approval from HMT, which would have been tough given the privatisation plans. The 365's from memory were only ordered after a competition with InterCity who wanted another batch of Class 91's and Mark 4's for the WCML. The 365's of course were the very last new trains ordered by BR pre-privatisation and there was the three year gap before the 168's were ordered by Chiltern.

 

[JonathanH]

They'd have to have got approval from HMT, which would have been tough given the privatisation plans.

The approval to remove locomotive hauled trains on Waterloo to Exeter would almost certainly have been forthcoming regardless of the solution, given the cost of that operation. 159s worked when it did because Regional Railways had already ordered them, and needed to cut costs, and Network South East had to remove the locomotive hauled trains to similarly cut costs.

See https://www.railforums.co.uk/thread...ramming-in-general.256240/page-6#post-6470907 and https://www.railforums.co.uk/thread...he-network-southeast-era.286229/#post-7286334

 

[dk1]

The approval to remove locomotive hauled trains on Waterloo to Exeter would almost certainly have been forthcoming regardless of the solution, given the cost of that operation. 159s worked when it did because Regional Railways had already ordered them, and needed to cut costs, and Network South East had to remove the locomotive hauled trains to similarly cut costs.

See https://www.railforums.co.uk/thread...ramming-in-general.256240/page-6#post-6470907 and https://www.railforums.co.uk/thread...he-network-southeast-era.286229/#post-7286334

Those 158s diverted to NSE were the reason Swindon-Peterborough never got off the ground even though a trial run had taken place.

 

[Big Jumby 74]

Might have meant that 400hp was required rather than 350 though, with implications for maintenance and fuel consumption.

The 159/0 fleet as delivered in original format came with Perkins 400hp units, the second batch (159/1) arrived with Cummins 350hp units. Have a feeling from memory that the Cummins units replaced the Perkins ones after some time, although questions were asked (in house) about possible effects on timetable performance with said reduction in horses, particularly in relation to East of Basingstoke, but any such concerns proved groundless at that time.

 

[43096]

I think there was a proposal for a specific type of 16x based unit as an alternative, though it might have needed cab end gangways, so wouldn't have been a straight 166. Electrification and some type of HST were also on the table IIRC.

The HST idea was apparently floated around the time of East Coast electrification. In reality there was never a chance of InterCity releasing any of their premium trains for use on a secondary route.

 

[Clarence Yard]

The Waterloo-Exeter service in NSE days was going to be operated by the end door version of the Turbos, the class 171. A few 165 units were also due to be built for SW duties. The Turbos were to be an NSE standard and built in greater numbers than they actually were. At one time the 166 units were to be 4 coaches per set and both these and the 171 units were to be maintained in the HST shed at OOC.

What happened was the 1989/1990 public sector squeeze, not privatisation. The 5 year BR “Railplan” was constantly revised during 1990, future fleet totals being reduced with each iteration and, to save money, RR/NSE did the deal that created the 159 fleet.

The biggest issue for any aluminium build stock is degradation of the aluminium with age, principally through cracking.

 

[61653 HTAFC]

The 159/0 fleet as delivered in original format came with Perkins 400hp units, the second batch (159/1) arrived with Cummins 350hp units. Have a feeling from memory that the Cummins units replaced the Perkins ones after some time, although questions were asked (in house) about possible effects on timetable performance with said reduction in horses, particularly in relation to East of Basingstoke, but any such concerns proved groundless at that time.

I thought it was the Cummins engines that came in 350hp & 400hp varieties, with the Perkins engines all being 350hp?

 

[bramling]

The approval to remove locomotive hauled trains on Waterloo to Exeter would almost certainly have been forthcoming regardless of the solution, given the cost of that operation. 159s worked when it did because Regional Railways had already ordered them, and needed to cut costs, and Network South East had to remove the locomotive hauled trains to similarly cut costs.

See https://www.railforums.co.uk/thread...ramming-in-general.256240/page-6#post-6470907 and https://www.railforums.co.uk/thread...he-network-southeast-era.286229/#post-7286334

This is a fascinating “what might have been”. I guess there would have been some kind of 166-based order, though interesting to surmise how it might have been funded. Agree the loco hauled operation probably wouldn’t have survived the NSE era. Had it done so then presumably we’d probably have seen a Turbostar variation.

Alternatively, perhaps NSE might actually have managed to electrify all the way down to Exeter, or to at least Salisbury, with Salisbury-Exeter split off and handed to RR. One presumes the cost of 3rd rail to Exeter would have been quite prohibitive, so had it happened we’d probably have ended up with a “lightweight” scheme that might ultimately have proved restrictive.

 

[Big Jumby 74]

I thought it was the Cummins engines that came in 350hp & 400hp varieties, with the Perkins engines all being 350hp?

It was a long time ago and my memory is far from infallible, but the name 'Cummins' I am certain was a new name in engines (to me) at the time, and as said, there definitely were concerns raised about the timekeeping of the units fitted with the smaller (power) units. Minutes of meetings have long since gone of course, so can't be any more certain that that?

PS: a bit of digging: yes, the Cummins came in both 350 & 400 variants, so would seem the 400 version replaced (over time) the 400 Perkins in the 159/0s. The 159/1's (AFAIK) have always retained their 350 lumps?

Anyway, this is straying in to the historic theme!

 

[Clarence Yard]

This is a fascinating “what might have been”. I guess there would have been some kind of 166-based order, though interesting to surmise how it might have been funded. Agree the loco hauled operation probably wouldn’t have survived the NSE era. Had it done so then presumably we’d probably have seen a Turbostar variation.

Alternatively, perhaps NSE might actually have managed to electrify all the way down to Exeter, or to at least Salisbury, with Salisbury-Exeter split off and handed to RR. One presumes the cost of 3rd rail to Exeter would have been quite prohibitive, so had it happened we’d probably have ended up with a “lightweight” scheme that might ultimately have proved restrictive.

Did you read #103? The detail is below.

The March 1990 version of the BR NSE Railplan had the SW fleet as 78 cars of cl.171 and 6 cars of cl.165, full fleet being reached in May 1992, when the LHCS would finally be withdrawn. The proposed LHCS run down was 81 vehicles in Oct 1991, 24 in March 1992 and none in May 1992.

Electrification of the Waterloo-Exeter route wasn’t going to happen, hence the proposed cl.171 order.

Funding for new stock in 1990 would be via the usual manner, BRB borrowing off the Treasury. The privatisation constraints came in a couple of years later.

 

[Zomboid]

What would 6 x 165 have done in the SW area (I assume those are 3 x 2 car). The Romsey line was RR at the time wasn't it?

 

[Xavi]

What would 6 x 165 have done in the SW area (I assume those are 3 x 2 car). The Romsey line was RR at the time wasn't it?

Reading - Basingstoke possibly which was SR DEMU operated.

 

[Helvellyn]

Reading - Basingstoke possibly which was SR DEMU operated.

That would be my guess, as there were a handful of Salisbury-Basingstoke-Reading services with the DMUs as well. Likely just based at Reading with the other 165s if the 171s were to be Old Oak based.

== Doublepost prevention - post automatically merged: 5 Oct 2025 ==

It was a long time ago and my memory is far from infallible, but the name 'Cummins' I am certain was a new name in engines (to me) at the time, and as said, there definitely were concerns raised about the timekeeping of the units fitted with the smaller (power) units. Minutes of meetings have long since gone of course, so can't be any more certain that that?

PS: a bit of digging: yes, the Cummins came in both 350 & 400 variants, so would seem the 400 version replaced (over time) the 400 Perkins in the 159/0s. The 159/1's (AFAIK) have always retained their 350 lumps?

Anyway, this is straying in to the historic theme!

The 159/0s were never fitted with Perkins engines. Just 158815-158862 got those.

 

[JonathanH]

That would be my guess, as there were a handful of Salisbury-Basingstoke-Reading services with the DMUs as well. Likely just based at Reading with the other 165s if the 171s were to be Old Oak based.

The final 2-car 165 in the Thames build was nominally for the Reading to Basingstoke line according to information at the time.

As you say there had been Salisbury-Basingstoke-Reading services in reaction to the poor reliability of the locomotive hauled trains, but they got restored to Waterloo as part of the 159 introduction.

 

[tfw756rider]

PS: a bit of digging: yes, the Cummins came in both 350 & 400 variants, so would seem the 400 version replaced (over time) the 400 Perkins in the 159/0s. The 159/1's (AFAIK) have always retained their 350 lumps?

No 400hp Perkins.

350hp 14-litre Cummins, 350hp 12.2-litre Perkins and 400hp 14-litre Cummins.

 

[Snow1964]

What would 6 x 165 have done in the SW area (I assume those are 3 x 2 car). The Romsey line was RR at the time wasn't it?

Reading-Basingstoke was main one, but until the Solent lines were electrified in 1990, the DEMUs (and some 33/1 + 4TC) did some odd first train and late evening workings too.

From memory there were workings in early 1990s to Woking, Eastleigh etc, possibly to allow power to be off for few hours overnight if required.

Going back to the main thread topic, the youngest of the 158, 159, 165, 166 fleet is now 33 years old, and some are now around 37 years old. An aluminium bodied carriage on a steel underframe is not the easiest type to weld in a bit if it is rusting, even harder if got corroded aluminium joined to steel.

It is already proving difficult to source enough spares to keep the whole fleet going. Can probably keep 90-93% of each fleet going 4 or 5 years (with others as spare parts donors).

I suspect the overhauls and maintenance costs are already close to point where adding in extra repairs for life extension is worst financially (on a 30-35 whole life basis) than replacing them asap. Actually I would not be surprised if already beyond that point and the cost of not being able to withdraw a few for spares (which can't yet be done due to lack of alternatives for each line) is making keeping 100% in service a very expensive short term option.

 

[JonathanH]

Actually I would not be surprised if already beyond that point and the cost of not being able to withdraw a few for spares (which can't yet be done due to lack of alternatives for each line) is making keeping 100% in service a very expensive short term option.

Even if it is, it is just a factor hidden away in the general 'subsidy is too expensive' bucket, rather than money being paid to rolling stock providers for higher lease costs.

 

[Farnborough]

Reading - Basingstoke possibly which was SR DEMU operated.

Which is quite interesting, given that this route *is* 165 operated!

 

[JonathanH]

Which is quite interesting, given that this route *is* 165 operated!

I think Reading to Basingstoke explicitly added one 2-car 165 to the Thames order. It never needed 6, nor indeed any 158s or 159s, even though SWT managed to identify some slack in diagrams to free up 159s for Reading to Brighton before the 170s arrived.

 

[martin butler]

These have now been operating for quite some time, alongside a few 158's Even with life extensions, eventually they will need replacing, but with what? what's the options?
1 Cascade other newer units, such as 800's or voyagers, assuming they can operate without danger of interfacing with the 3rd rail
2 purpose-built 3rd rail/ demu/ battery units, that can operate over both 3rd rail, and non-electrified tracks,
3 nothing run existing stock until overhead electrification of the line from Basingstoke

 

[3141]

I read some years ago that the bid for the franchise by Stagecoach in 2017 included bi-mode trains for the West of England line. I don't know if they would have been from Hitachi or Stadler.

A more recent suggestion has been to fit batteries to some class 450s, with some discontinuous electrification - I don't know whether it would be third rail or overhead. And with 2+2 seating, I would hope. Perhaps class 458/4 could be used instead.

As there are other areas where bi-modes will be needed, perhaps GBR could place an order for stock to meet all such requirements.

As class 170s become surplus in areas where electrification happens, transfer them to SWR. But I don't know if there are areas which would release a sufficient number of class 170s.

As for running the existing stock till overhead electrification takes place west of Basingstoke, the example of class 483 on the Isle of Wight, reaching 80 years old, provides a precedent of what would be necessary!!!

 

[martin butler]

I read some years ago that the bid for the franchise by Stagecoach in 2017 included bi-mode trains for the West of England line. I don't know if they would have been from Hitachi or Stadler.

A more recent suggestion has been to fit batteries to some class 450s, with some discontinuous electrification - I don't know whether it would be third rail or overhead. And with 2+2 seating, I would hope. Perhaps class 458/4 could be used instead.

As there are other areas where bi-modes will be needed, perhaps GBR could place an order for stock to meet all such requirements.

As class 170s become surplus in areas where electrification happens, transfer them to SWR. But I don't know if there are areas which would release a sufficient number of class 170s.

As for running the existing stock till overhead electrification takes place west of Basingstoke, the example of class 483 on the Isle of Wight, reaching 80 years old, provides a precedent of what would be necessary!!!

Could Hitachi 800's be adapted to operate off of 3rd rail? and use diesel for the non-electrified sections, or even a tri mode o/h, 3rd rail, and diesel, assuming they are cleared for operation over 3rd rail areas, have short swing bogies etc,

 

[gabrielhj07]

3 nothing run existing stock until overhead electrification of the line from Basingstoke

I think electrification of any kind west of Basingstoke should be preceded by doubling the majority of the line from Salisbury.

I‘d happily keep the 159s until the end of time.