What exactly is a coherent cascade plan?

[Kremlin Stooge]

Prompted by this comment in the Class 455 thread:

I'm not sure that we should celebrate unnecessary waste. A coherent cascade plan would make far more sense and avoid situations like the 455s and 458s getting withdrawn not long after serious money was spent on them, and 350/2s with no home to go to.

...what exactly is a “coherent cascade plan”?

I’m well aware that BR used to cascade stock that was deemed expired for ‘main line’ use to ‘secondary’ routes, because they had no real choice under the gimlet eye of the Treasury. Arguably one of the benefits of privatisation is that the operators and rolling-stock lessors could provide stock optimised for the routes in question. Equally arguably, this process started under Sectorisation, with (IIRC John Edmonds) the Director of Provincial Services holding out for 23m-bodied air-conditioned aluminium-body DMUs for the Sector’s key trunk routes. This gave us the Class 158. Now, considering a route close to my heart, the South Wales/South Coast services, under the BR regime of a “coherent cascade plan” this service was infested with fly-blown ex-mainline MK1s. A policy of procuring stock optimised for the route gave a vastly improved customer experience.

I dread to think what a “coherent cascade plan” would be offering up on this route today. Life-expired MK4s hauled by overweight Class 67s perhaps? A consist that would not be able to maintain current DMU-permissible speeds, particularly on the twisting sections of the route between Bath and Southampton.

{Routes that don’t go to London != Heritage routes}

Be careful what you wish for...

 

[Mat17]

Life expired MK4s are still a mark up on 150s, 153s or the recently culled Pacers mind.

 

[norbitonflyer]

Life expired MK4s are still a mark up on 150s, 153s or the recently culled Pacers mind.

TfW is snapping up Mark 4s for both the Holyhead - Cardiff and Manchester - Swansea routes. According to "Modern Railways", not having a diesel engine throbbing away under your seat for several hours is seen as an improvement (which is hardly a surprise to the travelling public, even if it is to whoever procured Voyagers, IEPs, etc) It will be interesting to see if the improved environment on the "Marches" line attracts people away from the Cross Country services between the NW and SW

 

[Roast Veg]

Running older stock at slower speeds signifcantly improves its working life. Where the stock is able to fulfill the requirements of the passengers, including fleet size, loadings, timings, boarding speed, etc - that is a "coherent cascade". The HSTs to the South West and Scotland, for instance, are capable of meeting the requirements set out by the stakeholders.

We use the term "life expired" a lot. The reality is that nothing is ever "life expired", just "more expensive today than the cost of a replacement".

 

[InTheEastMids]

what exactly is a “coherent cascade plan”?

The first place to start is identifying the changes or needs around rolling stock e.g.
- you have new infrastructure and that means new stock that's going to create a surplus (e.g. Crossrail, TL)
- pressing need to increase capacity
- requirement to retire old stock

and look at the match between where you have surplus/supply, where you have demand and then thinking through the infrastructure issues around matching supply to demand.

I think it's not worked all that well recently for 3 reasons.

Firstly, there is a mismatch between supply (i.e. what is available for cascade) and demand for passenger stock - e.g. a lot of what's been freed up is IC125s and 25kV EMUs. However the pressing demand has been to replace 14x and 15x DMUs that are inadequate for multiple reasons. The 769 is a comparatively low-capex bodge to address this mismatch (because the alternative cascade is electrification and using all the redundant 365s).

Secondly, a lot of the stock becoming available is getting towards end of life anyway. Growing up on the WCML I saw 20-25yo 310s replaced by <10yo 317s and then 321s. This approach is based on stock with significant life left being able to be redeployed to broadly similar duties - i.e. low risk. However, a lot of what has been freed up is not mid-life 10-20 yo, but 25+ yo and has needed substantial investment to produce a modern passenger experience - these forums are strewn with discussion on projects that have generally under-delivered (HSTs, 769s) or failed entirely (442s).

So perhaps we should challenge this idea that cascading is a Good Thing - i.e. maybe it only works well if the deployment is to a broadly similar usage (e.g. 360s to EMR). If there's a lot of engineering to make it work, then that looks set up to fail. It doesn't bode well for those talking up further hybrid, battery or fuel cell conversions.

Industry-level indecision is the third issue, particularly a failure to grasp the nettle on electrification, which would have leveled up supply and demand by increasing DMUs available, whilst also increasing demand for 25kV EMUs

 

[Mat17]

The pressing demand has been to replace 14x and 15x DMUs that are inadequate for multiple reasons.

It's always the way though isn't it? The provincial services always get the cast offs... Not very glamorous the leafy diesel lines.

Only 1st gen DMUs, then sprinters/Pacers and now class 195 were new.

 

[bramling]

Prompted by this comment in the Class 455 thread:

...what exactly is a “coherent cascade plan”?

I’m well aware that BR used to cascade stock that was deemed expired for ‘main line’ use to ‘secondary’ routes, because they had no real choice under the gimlet eye of the Treasury. Arguably one of the benefits of privatisation is that the operators and rolling-stock lessors could provide stock optimised for the routes in question. Equally arguably, this process started under Sectorisation, with (IIRC John Edmonds) the Director of Provincial Services holding out for 23m-bodied air-conditioned aluminium-body DMUs for the Sector’s key trunk routes. This gave us the Class 158. Now, considering a route close to my heart, the South Wales/South Coast services, under the BR regime of a “coherent cascade plan” this service was infested with fly-blown ex-mainline MK1s. A policy of procuring stock optimised for the route gave a vastly improved customer experience.

I dread to think what a “coherent cascade plan” would be offering up on this route today. Life-expired MK4s hauled by overweight Class 67s perhaps? A consist that would not be able to maintain current DMU-permissible speeds, particularly on the twisting sections of the route between Bath and Southampton.

{Routes that don’t go to London != Heritage routes}

Be careful what you wish for...

I’d say a rolling stock strategy decided by what the industry feels is necessary and sensible, rather than essentially dictated by the franchising cycle / process.

Also not replacing half-life stock without a definite plan for how it will be gainfully utilised for the remainder of its life. “It’s the leasing company’s problem” isn’t really good enough (IMO).

 

[daikilo]

It's always the way though isn't it? The provincial services always get the cast offs... Not very glamorous the leafy diesel lines.

Only 1st gen DMUs, then sprinters/Pacers and now class 195 were new.

And 150-159, 170, 175, 185, 331 ...

The question is currently what to do with the sometimes specific stock being replaced after say 20 years by new more flexible or faster stock. The 158/159s and 170s have shown how suitable they are for varied front-line jobs and possibly more so than the newer 175 and 185s.

Another case in point is the cl68+mk5 which really are odd-balls selected more for urgency than suitability for cascading.

 

[Dr Hoo]

It's always the way though isn't it? The provincial services always get the cast offs... Not very glamorous the leafy diesel lines.

Only 1st gen DMUs, then sprinters/Pacers and now class 195 were new.

Am I misunderstanding your (possibly ironic) post?

You seem to be pointing out, quite correctly, that many 'provincial' lines have had three successive generations of purpose-designed brand new stock that have largely worked out their lives on the lines for which they were intended.

Viz 1st generation DMUs in the 1950s-1980s; Pacers and Sprinters in 1980s-2010s; and finally Class 195s (and other third generation designs e.g. in South Wales) for the next thirty years.

No cascades involved. No cast-offs.

We can agree that previous generations of stock got a bit shabby and dated towards their demise but that isn't a cascade issue.

 

[mmh]

Am I misunderstanding your (possibly ironic) post?

You seem to be pointing out, quite correctly, that many 'provincial' lines have had three successive generations of purpose-designed brand new stock that have largely worked out their lives on the lines for which they were intended.

Viz 1st generation DMUs in the 1950s-1980s; Pacers and Sprinters in 1980s-2010s; and finally Class 195s (and other third generation designs e.g. in South Wales) for the next thirty years.

No cascades involved. No cast-offs.

We can agree that previous generations of stock got a bit shabby and dated towards their demise but that isn't a cascade issue.

No cascades or cast-offs? Really? As you mention South Wales, even a cursory think of the past decade shows that to not be the case there.

Class 153, 121, Mk3 and Mk4 coaches and class 769? All very much cast-offs.

 

[daikilo]

No cascades or cast-offs? Really? As you mention South Wales, even a cursory think of the past decade shows that to not be the case there.

Class 153, 121, Mk3 and Mk4 coaches and class 769? All very much cast-offs.

All of these could have been part of a cascade plan except there wasn't one. All except the 769 are suitable for the job with the jury being out on the latter which anyway should be relatively short lived on the currently planned operation.

It would however be fair to say that the mk4s were replaced by the 80x without apparently any thought as to what the leaseco would do with them. Maybe they are fully ammortised?

The current use of HSTs in Scotland and on GWR are an example of a practical cascade even if unplanned whereas the transfer of the 170s to TfW only to have them taken away again is a lack of a real plan given the time and cost of wasted training.

 

[Mollman]

A coherent cascade plan should go arm in arm with the 30 year vision and retendering plan so that when route X gets upgraded it can receive stock cascaded from route Y which has just had newer trains. Unfortunately for the new look railway any comprehensive cascade plan will have to do battle with increased regional influence. For example further electrification in the North West can be planned to go arm in arm with mid-life EMUs being released elsewhere however a certain Mayor will turn up on the telly demanding brand new stock and not 'London cast-offs' even though that will increase subsidy levels.

 

[30907]

No cascades or cast-offs? Really? As you mention South Wales, even a cursory think of the past decade shows that to not be the case there.

Class 153, 121, Mk3 and Mk4 coaches and class 769? All very much cast-offs.

Yes, but apart from the 153s (newer than 150s anyway) that's a handful of vehicles out of the total fleet - until the 769s as stopgaps.

 

[Doomotron]

There are very few circumstances where a 'coherent cascade plan' can happen; most of the time it can't work properly. For example, with Southern's 171s, the only fleets that could realistically replace them were the 156s, 158s and 185s. Not one of them is acceptable for Southern, the passengers, or both. In that case, any swap is a downgrade, but now the 171s aren't required it's no longer an issue, but plenty of these issues exist in other cases. While many seem to really want the Class 350/2 for SWR, the fact is that they're AC units (needing heavy modifications to work on the DC network), with 3+2 seating, which SWR are trying to get rid of on the PDL. Of course, they could refurbish them, but then the seats will probably be worse than what they have now and in the 444s, and there's the AC issue still...