How many?

[AberdeenBill]

HI all,

 

Hopefully not a stupid question.    Let's say that rolling stock on a certain route is having a major update and the timetable is being 'transformed'.   How are the required number of locomotives, multiple units and carriages worked out?   Obviously enough to cover a certain number of 'daily diagrams' but also presumably some for maintenance, works overhaul and 'spare'...     As an example, the 1967 Bournemouth electrification  (+ diesel power to Weymouth)needed 11 4-Reps., 28 4-TCs. 3 3-TCs, 20 4-Veps and 19 multiple-unit Cromptons (class 33/1).   The number of 33/1s seems significantly more than needed for the Bournemouth-Weymouth portion?     Why 11 Reps and not 10 or 12... ?       Or what about the nice round number of 50 ETH fitted 45/1s + an unknown numbers of air-conditioned Mk2s for the Midland main line upgrade. 

 

Thanks,

Bill

 

 

[slilley]

HI all,

 

Hopefully not a stupid question.    Let's say that rolling stock on a certain route is having a major update and the timetable is being 'transformed'.   How are the required number of locomotives, multiple units and carriages worked out?   Obviously enough to cover a certain number of 'daily diagrams' but also presumably some for maintenance, works overhaul and 'spare'...     As an example, the 1967 Bournemouth electrification  (+ diesel power to Weymouth)needed 11 4-Reps., 28 4-TCs. 3 3-TCs, 20 4-Veps and 19 multiple-unit Cromptons (class 33/1).   The number of 33/1s seems significantly more than needed for the Bournemouth-Weymouth portion?     Why 11 Reps and not 10 or 12... ?       Or what about the nice round number of 50 ETH fitted 45/1s + an unknown numbers of air-conditioned Mk2s for the Midland main line upgrade. 

 

Thanks,

Bill

 

Bill

 

I have been looking at the 33s a bit recently, and the Southern's early plans for the Bournemouth electrification scheme included 50 of them being converted to push-pull working. Similarly the number of big electro-diesels started out at 21 and gradually reduced as the scheme was refined. That story is told in some detail in my book on the 71s and 74s published late last year.

 

Best wishes

 

Simon

[The Johnster]

This is one of the drivers of shorter journey times and increased speed; it releases stock for cascading or disposal.

 

Timetabling is a dark art, though, practiced in gothic subterranean halls by men in hooded cloaks which are not so much black as an absence of light, their gaunt and haunted faces hidden from view but their eyes glowing, and the screams of tortured sacrificial victims in the background, just on the limit of your hearing.

 

It's true, I tells ya!

[Zomboid]

I don't know if it was part of the initial plan, but 33/1s and TC sets were also used on the Salisbury line, and could have been used a lot more widely than the REPs.

[HillsideDepot]

Timetabling is a dark art, though, practiced in gothic subterranean halls by men in hooded cloaks which are not so much black as an absence of light, their gaunt and haunted faces hidden from view but their eyes glowing, and the screams of tortured sacrificial victims in the background, just on the limit of your hearing.

 

It's true, I tells ya!

 

If my experience of scheduling in the bus industry is anything to go by you're pretty close to the mark! I was part of the team which introduced computer aided scheduling across First Bus, and whilst the Schedulers themselves were a great bunch, some companies had, if not hidden them in gothic subterranean halls, put them in a variety of "broom cupboard" type offices. And some of the subsidiary company Managing Directors were quite happy to admit that they had no real idea of what schedulers do, but they knew they had to have them - however if they could be hidden away, so much the better. Then again, there were a few Schedulers whose attitudes and language was, shall we say, out of step with the ethos of the modern open plan office. Their work though, was top notch.

 

But back on the topic, 308 class 37s, 512 class 47s, 31 class 91s looks like someone ordered enough (ok in batches in the case of 37s and 47s) for the work, including spares to cover works attention, but 50 class 50s, 58s or 90s, 100 class 60s looks rather like a neat round number than a defined need. And what about 101 Hymeks? Was that a round hundred based on someone thinking that was where the number D7100 left it, forgetting D7000?

 

Not exactly a numbers question, but it has long puzzled me why BR built 56s and 58s at the same time, especially as 56 production had to move from Doncaster to Crewe to allow Donny to build the 58s. Why not keep 56s at Doncaster and build 58s at Crewe, or indeed why not increase the order for either 56s or 58s to have a Type 5 fleet of just one type. If the 58 was an advance, why build more 56s? The only thing I can think is that BR needed two production lines to meet demand (or spend the funding before Government found a "better" use for it), but the question remains, why 2 types at the same time?

 

As for maintenance spares, presumably the manufacturer offers some sort of figure there. First bus used to work on 10% spare, which was great if you had a standardised fleet, but the depot I worked at had a very mixed fleet of types, big, small and low floor single deck buses, tall and low double deck buses, National Express coaches, open top tour buses, etc etc where 10% spare on the overall depot allocation caused some problems with the less numerous types.

 

I await, with interest, replies from those more knowledgeable than I.

[luckymucklebackit]

If my experience of scheduling in the bus industry is anything to go by you're pretty close to the mark! I was part of the team which introduced computer aided scheduling across First Bus, and whilst the Schedulers themselves were a great bunch, some companies had, if not hidden them in gothic subterranean halls, put them in a variety of "broom cupboard" type offices. And some of the subsidiary company Managing Directors were quite happy to admit that they had no real idea of what schedulers do, but they knew they had to have them - however if they could be hidden away, so much the better. Then again, there were a few Schedulers whose attitudes and language was, shall we say, out of step with the ethos of the modern open plan office. Their work though, was top notch.

 

But back on the topic, 308 class 37s, 512 class 47s, 31 class 91s looks like someone ordered enough (ok in batches in the case of 37s and 47s) for the work, including spares to cover works attention, but 50 class 50s, 58s or 90s, 100 class 60s looks rather like a neat round number than a defined need. And what about 101 Hymeks? Was that a round hundred based on someone thinking that was where the number D7100 left it, forgetting D7000?

 

Not exactly a numbers question, but it has long puzzled me why BR built 56s and 58s at the same time, especially as 56 production had to move from Doncaster to Crewe to allow Donny to build the 58s. Why not keep 56s at Doncaster and build 58s at Crewe, or indeed why not increase the order for either 56s or 58s to have a Type 5 fleet of just one type. If the 58 was an advance, why build more 56s? The only thing I can think is that BR needed two production lines to meet demand (or spend the funding before Government found a "better" use for it), but the question remains, why 2 types at the same time?

 

As for maintenance spares, presumably the manufacturer offers some sort of figure there. First bus used to work on 10% spare, which was great if you had a standardised fleet, but the depot I worked at had a very mixed fleet of types, big, small and low floor single deck buses, tall and low double deck buses, National Express coaches, open top tour buses, etc etc where 10% spare on the overall depot allocation caused some problems with the less numerous types.

 

I await, with interest, replies from those more knowledgeable than I.

 

If my memory serves me right from reading the magazines of the day, the class 56 filled an urgent need for locomotives to haul MGR trains following the oil crisis of the early 70s and were only ever intended for that purpose in the UK. The class 58 was for a similar purpose in the UK, but was designed for easy maintenance aimed at foreign (3rd world?) buyers, in the hope that the UK locomotive building industry could get back into the export market, unfortunately that aspiration was never fulfilled.

 

Jim

[Rivercider]

I suspect that with an ever changing railway network those in charge of providing resources for for future traffic flows

are trying to aim at a continually moving target. I don't know much in detail about the Bournemouth electrification scheme

but I would hazard a guess that in the time between the initial planning and the final introduction of the total scheme that

traffic levels had altered and the timetable had changed.

 

Another example that I had been thinking about recently was the Western Region decision to use hydraulic traction

and the numbers of locos built, particularly classes 22, 42 and 43. Imagine that the regional boundary changes of 1963 had not happened

and the Western had not taken over Southern lines in the far west, or taken over responsibility of traction for the Waterloo-Exeter route?

At a rough guess perhaps 10 class 22s and 10 Warships ended up working on former SR routes, and had they not done so those classes

might have become extinct a year or two earlier,

 

cheers 

[rodent279]

IIRC, 56 production was at Doncaster because Crewe, being tied up with HST production, couldn't handle it. When HST production started to ramp down, 56 production was moved to Crewe, allowing Doncaster to focus on the class 58's.

Regarding our locomotive building industry, I can't help thinking that really, come the 1980's/1990's, it was a bit of a cottage industry compared to the continental manufacturers. Yes we could and did build quality products, the HST being the shining example in my view, but the volume was never there, there was never the capacity that foreign plants had.

Doncaster & Crewe were rather slow in fulfilling the class 56 orders. It took something like 6 yrs to build 85 56's at Doncaster, Crewe did the last 20 in around 20 months. Doncaster then took 5 yrs to build all 50 class 58's, that's less than 1 per month.

 

Edit:-don't forget that the first 30 build was sub-contracted out to Romania because Doncaster had to tool up for production, not having built any locos in quantity for over a decade, & BR needed the locos urgently.

Edited January 10, 2018 by rodent279

[Ray H]

You work out the schedule requirement, add on the spares for the more regular maintenance (but not part life rebuilds, which wouldn't be known about) and then you submit for funding. Everything gets heavily scrutinised and paired back to the bare minimum and (if your lucky and minds haven't been changed) the order gets placed. You then keep your fingers crossed that nothing gets written off in a prang or such like as that eats into the part of the fleet number that were bought to cover maintenance.

 

Signed

Railway modeller who is an ex scheduler - is there any hope for me?

[rodent279]

 

Not exactly a numbers question, but it has long puzzled me why BR built 56s and 58s at the same time, especially as 56 production had to move from Doncaster to Crewe to allow Donny to build the 58s. Why not keep 56s at Doncaster and build 58s at Crewe, or indeed why not increase the order for either 56s or 58s to have a Type 5 fleet of just one type. If the 58 was an advance, why build more 56s? The only thing I can think is that BR needed two production lines to meet demand (or spend the funding before Government found a "better" use for it), but the question remains, why 2 types at the same time?

 

 

If I'm not mistaken, I think the original plan was for 150 class 56's. That was revised to 135, with the last 15 ending up as class 58's, which were intended to be more general purpose than 56's.

 

56's themselves were done on the cheap really, in that they were basically a class 47 body with a revised, uprated & modernised EE engine driving an alternator, mounted on flexicoil suspension derived from the HST & class 87 bogies. Not that I'm knocking them, they seem to have given good service.

Edited January 10, 2018 by rodent279

[Pete the Elaner]

You work out the schedule requirement, add on the spares for the more regular maintenance (but not part life rebuilds, which wouldn't be known about) and then you submit for funding. Everything gets heavily scrutinised and paired back to the bare minimum and (if your lucky and minds haven't been changed) the order gets placed. You then keep your fingers crossed that nothing gets written off in a prang or such like as that eats into the part of the fleet number that were bought to cover maintenance.

 

Signed

Railway modeller who is an ex scheduler - is there any hope for me?

I think you've just about hit the mark there.

These are not £3 lengths of flexi track for the layout, they are £1 000 000+ locos built for companies wanting to make every penny of profit they can.

It may have been different in BR days when it was all public money, but before then it was similar. Back in LMS days, there were 12 Princesses (+ the turbo), 38 Duchesses, all ordered in smaller batches to cope with increasing demand.

It is the same in most industries. Most companies start off deciding how many of something they want then, once the cost is worked out, this is reduced by those who sign off the spending.

[The Stationmaster]

HI all,

 

Hopefully not a stupid question.    Let's say that rolling stock on a certain route is having a major update and the timetable is being 'transformed'.   How are the required number of locomotives, multiple units and carriages worked out?   Obviously enough to cover a certain number of 'daily diagrams' but also presumably some for maintenance, works overhaul and 'spare'...     As an example, the 1967 Bournemouth electrification  (+ diesel power to Weymouth)needed 11 4-Reps., 28 4-TCs. 3 3-TCs, 20 4-Veps and 19 multiple-unit Cromptons (class 33/1).   The number of 33/1s seems significantly more than needed for the Bournemouth-Weymouth portion?     Why 11 Reps and not 10 or 12... ?       Or what about the nice round number of 50 ETH fitted 45/1s + an unknown numbers of air-conditioned Mk2s for the Midland main line upgrade. 

 

Thanks,

Bill

 

It can be a simple or complex as you care to make it.

 

The first things you need to decide are whether you are going to have a resource led timetable or a commercial specification led timetable - in practice for the last three or four decades UK practice has been a mixture of the two,  In contrast SNCF for example concentrate, for Grandes Lignes in particular, work very much on a commercial specification timetable although the result tends to lead to very inefficient use of resources (but that's typical of much of SNCF I'm afraid).

 

Resource led effectively means we can afford (or are prepared to pay for) X number of trains and crews to work our service and we will have to build the timetable from that.  The matter of timings, number of intermediate stops and so on then comes into play to calculate the frequency you can achieve with those resources.

 

If you do it the other way round the commercial specification decides the frequency and then using journey time and any restrictions relating to traincrew etc you calculate the resources needed to run that timetable.  During development - from either starting point - any decent trainplanner will be looking for ways to get an improvement in the overall efficiency of a timetable which can mean looking at potential for reducing the cycle times of trains and crews.  The cycle time can be constructed from various starting points but will include journey time and turn round time at both ends of the journey and is the critical element whatever your starting point.  Cycle times can be reduced by eliminating intermediate stops, by improvements in train and or line speeds, and by reviewing pathing to reduce potential conflicts.  Turnround times at stations can be altered by the amount of time needed to discharge and load passengers, to clean the train, to add or remove catering stores and label seats for reservations.  For exa,ple once the full electronic reservation system is working on the Class 800 trains there will be a potential time saving on seat labelling at turnrounds.

 

Putting the whole lot together into a workable and hopefully resilient trainplan which meets the final commercial specification - or gets as close to it as the commercial folk will accept is the aim in the British way of tackling the job.

 

In terms of traction and rolling stock fleets the process is basically very simple - you calculate how many things you need to run your service and then add a percentage to meet maintenance needs - the levels of maintenance which takes trains out of service.  Equally you can work to a pre-planned availability level and tell your traction and rolling stock engineers to meet it but the system is usually iterative.  (Although some years ago when i was doing a major timetable risk assessment process - which I widened to include the essential element of timetable development - on the suburban network of a major overseas operator I discovered there were no agreed availability figures for any part of their very large fleet.  The traction engineer simply had the traffic requirement dumped on him at each change of timetable; utterly unbelievable in the 21st century and hardly surprising that timetable reliability suffered because in some cases the required availability was impossible to achieve.

 

In practice of course the iteration and interaction between the various elements can get very complicated but having spent over a decade running both freight and passenger planning teams it can be immensely satisfying to see something your past mental gymnastics and fiddling around (sorry detailed planning) out on the real railway running about as rail trains and the plan working perfectly.   And sometimes it can be extremely interesting - back in the early '90s OI had the pleasure, and brain ache, of developing a major freight scheme literally from the ground up doing not just a trainplan but planning infrastructure alterations to handle the service I need to handle the specified tonnages and planning a loading terminal to load it, great fun and i even 'borrowed' a Class 60 and a loaded train to check out various shunting timings where I need full information to help me decide the best way to do part of the job - not many planners got that sort of chance.

 

PS Enough of broom cupboards and gothic subterranean holes - in two of my train planning jobs on BR (and into privatisation in the latter one) my office windows looked out directly on the very services my team and I were planning although I did have to turn round to look out of the window .

Edited January 10, 2018 by The Stationmaster

[caradoc]

When the route from Paisley to Ayr and Ardrossan was electrified in the 1980s BR calculated the number of Class 318 sets required to provide the specified service level as 20; Initially Ardrossan South Beach/Largs was not to be wired, being served by a diesel shuttle instead. When it was subsequently decided to wire through to Largs, one (1) additional Class 318 set was required. The effect of this can still be seen, in that the vehicle numbers of the additional set (318270) do not follow on directly from the first 20.

 

As an aside, showing how tight BR was for resources; Part of my job was recording the daily availability of Corkerhill Depot's DMUs. Corkerhill was on top of things and regularly had a spare 156, however we were advised not to show this in our returns as otherwise a Class 156 would get transferred away to another depot !

[Southernman46]

This is one of the drivers of shorter journey times and increased speed; it releases stock for cascading or disposal.

 

Timetabling is a dark art, though, practiced in gothic subterranean halls by men in hooded cloaks which are not so much black as an absence of light, their gaunt and haunted faces hidden from view but their eyes glowing, and the screams of tortured sacrificial victims in the background, just on the limit of your hearing.

 

ISTR at Waterloo (Lovingly??) referred to as "The Cardigans" by we Visgoths at the sharper end of things ......................................

[The Stationmaster]

ISTR at Waterloo (Lovingly??) referred to as "The Cardigans" by we Visgoths at the sharper end of things ......................................

 

Knowing those responsible in Railtrack days for the possession programme on South Zone I would say that the term Visigoths should have been more rightly applied to them - they were never my flavour of any month.

[Bedders]

As an aside, showing how tight BR was for resources; Part of my job was recording the daily availability of Corkerhill Depot's DMUs. Corkerhill was on top of things and regularly had a spare 156, however we were advised not to show this in our returns as otherwise a Class 156 would get transferred away to another depot !

 

I therefore blame you for inflicting pacers on me between Sheffield and Scunthorpe!