How are diagrams "built"?

Discussion in 'Allocations, Diagrams & Timetables' started by robert7111a, 9 Oct 2019.

  1. robert7111a

    robert7111a Established Member

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    With lots of interest around unit/loco diagrams etc, I am very curious as to how a diagram is actually conceptualised, worked out and built?
     
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  3. 306024

    306024 Established Member

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    Good question! I’ll try to give a concise answer but there are lots of factors involved.

    It all starts with the design of the timetable. The timetable will be planned to take account not only of the journey time, stops, etc, but most importantly the platform capacity at terminal stations. It is this which determines how long trains can wait before forming their next working. At some locations where there is lots of platform capacity and many trains the diagrammer could have a choice of what to do, where as a location where platform capacity is at a premium the diagrammer may have no choice.

    So you set off linking individual schedules together to start to build a diagram. Electric fleets are easier as you don’t have to consider fuel range. Once you have covered every schedule you will have a set of diagrams. Now it is important that these balance, that is to say the same number of trains finish at each location as are required to start the next day. If they don’t you may need to request an additional empty movement, or perhaps run an additional passenger train, of if possible couple units together.

    You will then have to consider how these diagrams work for maintenance requirements, including watering, emptying toilet tanks, fuel as already mentioned and links to maintenance depots. You may need to go back and change something you have already diagrammed to make it work.

    You will also have to match capacity to demand. Easier said than done as information on passenger loadings will be a year out of date by the time your timetable starts. Off peak demand has increased on many routes where trains used to be reduced in length between the peaks but now remain the same length all day.

    That’s the basics for diagramming the units. Similar principles for locomotives, but it’s a lot easier these days with push-pull working. Individual locomotive diagramming on passenger trains where the locomotives had to be attached / detached at terminals was a fascinating logistical puzzle. Pleased to say I did this job for many years.

    And then there is traincrew diagramming. You don’t want to diagram a train to a route where the traincrew don’t know the traction. Sounds obvious but has to be taken into consideration.

    I could go on but that’s the gist of it. Hope it provides some insight.
     
    Last edited: 9 Oct 2019
  4. Brissle Girl

    Brissle Girl Member

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    Which all could explain why when at very short notice Northern and Thameslink has to redo theirs for May 2018 it all collapsed in a heap. Northern as a result of Network Rail’s failure to electrify both the Blackpool and Bolton lines in the timescales promised and Thameslink because the SoS made some ill advised decisions regarding the scope of changes at (in timetabling terms) very short notice. So both were the responsibility of government in its various guises, but of course it was the TOCs that for the bashing.
     
  5. 156420

    156420 Member

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    From a controllers perspective (not in terms of train planning in the way the diagrams are built) in terms of allocating units to their diagrams for an EMU fleet, I’m looking at the miles and the days since the last exam and looking forward days in advance to make sure a unit is on the correct diagram cycle so it gets an exam without running out of miles or days.

    Say I have Unit 1 which has 400 miles left before it’s next exam:

    It’s next diagram on one day might be 250 miles but then the next day it will end on a diagram that is 300 miles, I know I will need to swap the unit over, or allocate it to a shorter/different diagram on my stabling and start of day plan, so that it goes for an exam within the mileage threshold. This is a common reason why we have unit swaps.

    That’s a very simplified example, diagram cycles can work if everything is running as booked, but throw in service disruption and train faults and that’s when you earn your money in making sure units don’t run out of miles before exam.
     
  6. edwin_m

    edwin_m Veteran Member

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    Also trains aren't usually subject to maximum working hours or mandatory rest breaks, and can't travel to different locations inside other trains or taxis. So there are a lot more variables to play with in crew diagramming.
     
  7. robert7111a

    robert7111a Established Member

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    Ah yes but I have heard of trains being "out of miles" where exams, overhauls fall due
     
  8. robert7111a

    robert7111a Established Member

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    Thanks for explaining. I know diagramming is very complex and has to take account of many factors
     
  9. 306024

    306024 Established Member

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    You’re welcome. It is that complexity that makes it a fascinating job / career if you have a logical mind and a thirst for problem solving.
     
  10. 6Gman

    6Gman Established Member

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    I was also a diagrammer. Had the pleasure of working with a guy whose name I've sadly forgotten who was phenomenal at creating capacity within diagrams.

    For example, we needed a loco working from Derby at 0830, returning to Derby at 1800.

    I could find a loco from 0715 to 1400, and from 1630 to 2359 - but that isn't a lot of use!

    I'd take it to this guy, leave the problem with him, and twenty minutes later he'd be back with fingers in several pages of the diagrams.

    "Use Toton 25 to cover Toton 42 from 0620 to 1300; then use Toton 42 to cover Crewe 80 until 1225; Crewe 80 can then work vice [in place of] Toton 12 all day, releasing Toton 12 to cover your job. But you will need to send Toton 42 light to Burton at the end."

    And he never got it wrong. Brilliant!
     
  11. 6Gman

    6Gman Established Member

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    On the other hand, you can "create" extra traincrews if people are willing to work overtime or Rest Days.

    You can't use a unit on its Rest Day!

    (Though you can sometimes tweak the number of available units by tweaking maintenance.)
     
  12. Whisky Papa

    Whisky Papa Member

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    The Long Term Plan (LTP) diagrams should allow for exams to be taken at the right intervals. All things being equal, a unit should follow through the full cycle of diagrams for its class, which will include days allocated for exams.

    Two things (at least) can upset this, however. The LTP diagrams are regularly changed to allow for engineering work, which is the Short Term Plan (STP). With a mixed fleet of DMUs, multiple stabling locations and regular midweek overnight closures in the North West, Northern's LTP exists only as a theoritical starting point. There will be staff in Control who will keep tabs on where the units are and will try and allocate them to a suitable diagram to ensure they are back on depot for the exam at the required mileage.

    On top of that, there may be occasions during disruption when units are "stepped up" at terminal stations to form a different service to that diagrammed, which may affect where they end service that day. Sometimes they can be swapped back to their original diagram, sometimes not. A combination of these two circumstances may also occasionally result in units having to be swapped out because they are low on fuel, or even actually running out. The STP planner will ensure that the changes they make do not result in fuel shortage, but it is possible that a subsequent "step-up" that one worked fine the week before no longer does because the unit hasn't been fuelled overnight due to an STP change. Class 142s with only half the range of 15x units are the worst offenders, with overnight closures sometimes resulting in more units being stabled at Chester and not fuelled.
     
  13. ComUtoR

    ComUtoR Established Member

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    What percentage of a fleet is required to run a set of diagrams. As in how much slack is there built in ? There must be some allowance for units running as MO (Multiple Only) and units with various faults etc.

    Cheers in advance as always.
     
  14. 306024

    306024 Established Member

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    Fleet availability will vary by the type of train, but typically somewhere between 85% and 95% to give a rough figure. For example the Great Eastern 360 fleet have run on the basis of 20 diagrams from a fleet of 21 units most of the time (95.2%) on Monday to Friday, which is very high, although with provision for off peak maintenance built into the diagrams.

    The fleet team usually like a diagram that starts and finishes at the maintenance depot each day so they can get units back quickly for any work that may not have been completed. This is easy(ish) to plan on a railway that has a big peak demand but a lower requirement off peak. But they will also require links from all (or most) other stabling locations into the depot and sometimes you can’t achieve everything. Burying cab faults can usually be accommodated on some diagrams, or the opposite problem of non multiple working, but for a long term planner these are secondary considerations to the basics of fuel, water and toilet tank emptying.

    And then as stated above the long term base plan gets altered for a whole host of reasons, both planned and unplanned.
     
  15. 717001

    717001 Member

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    Lack of platform capacity at Moorgate (2) and required frequencies Mon-Fri means that weekday diagrams have to be mainly V shaped. Trains alternate between Welwyn Garden City and Hertford North routes. This has the result of quickly transferring any problems from one line to the other. Believe 25 trains are currently operating 21 diagrams - will rise to 23 in due course).
     
  16. Goofle

    Goofle Member

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    So on average how often does a unit (142, 15x, class 67 on passenger work) need to fuelled? I presume that it's not exactly a speedy evolution either?

    please ignore - Mr Google has provided the answer!
     
    Last edited: 10 Oct 2019
  17. Tom Quinne

    Tom Quinne Established Member

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    Poorly in most cases !
     
  18. Andy1673

    Andy1673 Member

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    "Building" of diagrams depends on many additional conditions most of them can be referred to train operating company`s or Network Rail`s requirements, particular features of timetable, character of flows in the TOC network or in its part(s). Platform capacity at termini, major stations, manner ot turnround (at platform, via siding, etc), size of depots and stabling points, trains` lenght, demand of splitting and attaching units during the day. Depending on all those and many others features diagramms can be planned and built either as "cycle" (number of units of particular type or different types working on one particular service or group of services repeteadly during the day, including or excluding peaks, early morning and late night variations) or "all works all" (number of units of definite type or different types working any services the TOC operates).
    For example Southern has different EMU types and one small DMU type. Things very vary.
    16 of 19 class 313 EMUs diagrammed on weekdays. It`s clear example of the "cycle" diagramming method. Almost every units have particular service pattern - Brighton to Lewes, Brighton to Seaford, others appearing more complicated - units operate Brighton to Hove or Brighton to Portsmouth almost all day but they can serve part of Brighton to West Worthing (plus peak services Brighton to Littlehampton) or Brighton to Hove services. Some units serve "complex cycle" - Littlehampton to Bognor, Bognor to Barnham and return, Bognor to Littlehampton, Littlehampton to Portsmouth (Southsea) and return and again in that order. Only 7 of 16 start and finish daily diagrams at various stabling points, others 9 start and finish at Lovers Walk depot. All 16 working all day and no midday depot stabling. All 16 working as single sets with no splitting and attaching.

    42 of 46 class 455s diagrammed daily on weekdays. Almost similiar but all working in pairs (21x2) and serve dedicated London`s metro routes (Victoria to Sutton (only one pair; others are 2x377/6), Victoria to Epsom Downs, London Bridge to Beckenham Junction, London Bridge to Caterham (crooked :)), London Bridge to Coulsdon Town, some others all days or peak-only). Majority of units start and finish daily diagram at depots (Selhurst, Stewarts Lane, Streatham Hill shed or sidings), only 8 (2x4) of 42 stabled overnight (all at London Bridge). Almost all working all day, only 3 pairs have midday depot stabling. No attaching or splitting.

    27 of 29 3-car class 377/3 diagrammed on weekdays. 3 of 27 run as single units on Redhill to Tonbridge route. Other 24 run in pairs and serve dedicated London`s metro routes with 1 377/1/4 as 10-car sets (Victoria to London Bridge, Victoria to West Croydon - these two interworked as "cycle", London Bridge to Epsom, Victoria to Epsom and Dorking). Only 7 of 24 London`s units stabled overnight at stations and sidings, other at depots (Selhurst, Stewarts Lane, Streatham Hill). No splitting and attaching during the day, only one ot 3 Redhill to Tonbridge stabled midday at Tonbridge sidings, others have no midday stabling.

    Huge class 377/1 and /4 comprises 136 units, 123 diagrammed on weekdays. Majority of units diagrammed for "cycle" working with early morning, peaks, late evening variations. Units operate
    as single, double or triple sets. Numerous splitting and attaching take place all day en route (for some services) or for capacity purposes (peaks) but 12 coupled with the pairs of 377/3 (see above) and have no splitting and attaching. Some units work all day at coastal services off Brighton (to Southampton, Hastings, Ore) and do not split too. Only 30 of 123 start or finish diagrams at major depots (Lovers Walk, Selhurst, Stewarts Lane or Streatham Hill), others stabled overnight at various stations and sidings including Victoria, Littlehampton, Bognor, Eastbourne, Horsham, Three Bridges and some others. Only 27 of 123 stabled at depots or sidings midday. None stabled overnight at another`s TOC lands (Southampton, Portsmouth (s), Ashford (for DMU 171s of course) though Southern serves these stations hourly or half-hourly all day.

    Relatively small class of dual-voltage 377/2 comprises 15 units, 14 of them diagrammed on weekdays (all as pairs). One pair operate Victoria to London Bridge and return, Victoria to West Croydon and return and so on, 6 other on East Croydon/Selhurst/Clapham Jn to Milton Keynes route demanding AC/DC. But one of these make one evening peak Victoria - Caterham/Tattenham Corner dividing at Purley, return working is empty to depot, both sets attached at Purley. All 14 diagrammed start and finish at Selhurst depot or Streatham Hill, only 4 stabled midday, no splitting and attaching except of above stated.

    31 of 34 class 377/6 and /7 diagrammed on weekdays. These EMUs operate dedicated London metro routes (London Bridge to Caterham/Tattenham Corner dividing at Purley, Victoria to Sutton except one pair of 455s, Victoria to Epsom/Dorking/Horsham, one pair Victoria to London Bridge and return, Victoria to West Croydon and return and so on, peak Victoria to Caterham. Almost all units dividing and attaching many times during the day. 8 of 31 stabled at depot midday. Only 7 of 31 start and finish at depots, others stabled overnight at various stations and sidings. Classes 377/6 and 377/7 diagrammed together as one class, 377/7 is dual-voltage class, it isn`t serving West London route though earlier was.

    Class 387 diagramming similiar as class 377/1/4 but easier because of fleet`s size (27 387/2s +387105; 25 diagrammed on weekdays) and there are only two possible routes - Victoria to Gatwick or Victoria to Brighton. There are numerous splitting and dividing. 17 of 25 units start and finish at depots (Stewarts Lane and Lovers Walk), 8 stabled overnight at Victoria and Hove. 7 units stabled at depots midday.

    DMUs class 171 also similiar as class 377/1/4 but again easier because of fleet`s size (8 4-car, 6 diagrammed; 12 2-car, 10 diagrammed) and only two routes - Ashord to Eastbourne and London Bridge to Uckfield. First ot them only 2-car units and no splitting and attaching; Uckfield route has a number of different formed sets (2 to 10 cars; 2 and 4-car units used) and there are numerous splitting and attaching. 4 of 6 four-car units stabled at depot midday and only 2 of 10 two-car units + one of Eastbourne to Ashford stabled midday at St Leonard`s shed. Almost all start and finish at Selhurst depot (only 3 two-car set stabled overnight at Eastbourne and St Leonards shed and one four-car set at Oxted).
     
    Last edited: 11 Oct 2019
  19. Cricketer8for9

    Cricketer8for9 Member

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    Thanks for this. There is also a 2x4 car am Caterham/Tattenham, forming the 07:19 from Purley to Victoria (07:22) at my station Purley Oaks.

    Actually more than thanks: a wonderful post.
     
  20. Andy1673

    Andy1673 Member

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    You are welcome!
    Cat/Tat to Victoria 07:19 at Purley is a part of two class 377/1/4 diagrams. They then form Victoria to Portsmouth and Bognor splitting at Horsham.
     
  21. Whisky Papa

    Whisky Papa Member

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    From memory, 14x units are given a nominal planning range of 800 miles and 15x 1500 miles, which I assume coincides with what you found?

    The standard train planning software shows the cumulative miles run since last the refuelling, and will link successive days diagrams together to show a running total. This is fine for the LTP, but when STP changes are made, the diagrams may no longer link from one day to the next in numerical order. This would mean either starting to renumber even more unit diagrams, which then requires more crew diagrams to be altered to show the revised unit numbers, or just link them with non-consecutive numbers. A footnote might be provided to tell Control that, say, diagram 404 on Monday evening which now stables at Chester must work diagram 422 from Chester on Tuesday morning so it will finish up at Newton Heath on Tuesday evening to be fuelled; the software will allow the cumulative mileage to still be shown in such cases. Obviously the stabling order must also be correct - no use specifying such a link if the required unit is blocked in at the buffer-stops in the platform in Chester by two others on Tuesday morning!
     
  22. whoosh

    whoosh Member

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  23. robert7111a

    robert7111a Established Member

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    Thank you for this and your personal insight/experience on the matter. I didn't realise just how many people were involved let alone all the intricacies etc etc... I know South Eastern is complex, but... I shall allow more thought to those planners when I have to travel on a day of engineering work
     
  24. Bikeman78

    Bikeman78 Member

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    Pre Thameslink the GN fleets at Hornsey were as follows.
    313 - 41 out of 44 (93%)
    317 - 10 out of 12 (83%)
    321 - 12 out of 13 (92%)
    365 - 38 out of 40 (95%)
    The three main line fleets often cross covered. There were two pairs of 365s that didn't split or join all day. One pair started at Horney and finished at Peterborough, the other pair did the opposite. However, both pairs stabled at Cambridge off peak and worked the 1415/1515 back up to King's Cross so there was scope to swap them over. The spare pair of 317s sometimes covered one of these pairs. Alternatively a 317 or 365 might cover the single 321 diagram and then all 13 321s would run with one pair covering a pair of 365s. There were 12 car 365s on the Peterborough line in the peaks. These were favourites for 365s with faults. Some of them spent weeks on those diagrams.

    As a comparison the AGA 317 fleet only requires 44 diagrams from 55 units which is only 80%. Admittedly they often have a pair on the Stansted express which bumps it up to 83%.
     
  25. ComUtoR

    ComUtoR Established Member

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    Cheers for the replies I'm still a little confused with how Maintenance and faults are dealt with.

    If you have 41/44 units needed to cover the diagrams then you have a potential 3 allowed for maintenance. However, if you have units running around in multiple or with faults that require them to be out of service, how is that dealt with ? Is it a case of cancellations ? I would be surprised if there was no allowance for faults and additional maintenance. With leaffall coming up; there will be a few units that will no doubt require the use of the lathe :)

    Cheers in advance again.
     
  26. northernchris

    northernchris Member

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    Really interesting thread, I hadn't considered all of the factors control have to deal with. Are there procedures which are followed when short formed occurs? For example are there some diagrams which are the first to drop a unit and some where every effort is made to run correct formation?
     
  27. 306024

    306024 Established Member

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    Routine preventative maintenance is usually built into the down time of the units. Southeastern like a lot of South-East TOCs presumably have quite a few diagrams where the trains sit in the depot between the peaks when exams can take place, or overnight. The extra 3 units (in the case of 41/44) are for more major exams that take days / weeks. Faults that are safe to run with simply wait until there is time to repair them.

    Leaffall usually results in short formations or cancellations if there a queue of units waiting for the wheel lathe. Only alternative is having more units, which don’t come cheap, assuming you’ve somewhere to park them.
     
  28. 717001

    717001 Member

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    Most GN Moorgate trains used to be run with 2 x 313, which meant that short-forming was an option or splitting one train to cover 2 services. Now the new 717s (like the TL 700s) are fixed formation, so there won't be any short forms but are likely to be an increased number of cancellations of at least part of a diagram.

    The fact the frequencies are largely maintained through the day M-F also reduces depot time.
     
  29. Bikeman78

    Bikeman78 Member

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    I have no specific inside knowledge about Hornsey but I do know that a few 313s parked up between the peaks; probably long enough to do an A exam. Back in the day when they worked peak hour trains from King's Cross to Royston there would be the odd unit with an AC only restriction. I remember 313026 was restricted to those for quite a while and it failed on me completely one evening, not long before the Royston workings finished. As it happens, it was the first to be withdrawn.

    For the mainline fleet, there were far more units stabled at Hornsey during the day than overnight so I expect most A exams were done on day shift. Generally they did a good job of turning out the required 60 units. It became challenging if a 365 had collision damage at the same time as overhauls were due. That meant both the spares were gone before anything else went wrong so the spare 317/321 were out almost every day.
     
  30. 156420

    156420 Member

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    Not specific to your area, but I operate a similar fleet and any units that are semi-permanently coupled due to motor restrictions etc, or non-multi due to coupler defects, I try and put on short diagrams, ie: ones that only do the AM/PM peaks, and I usually just have to keep swapping them over on certain diagrams, to keep them on these short workings.

    Just to complicate matters, I’ve got a unit that is only allowed to work a certain route, so I have to manipulate the train plan to keep it on there each day!
     
  31. nickw1

    nickw1 Member

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    Have said this in another (SWT/SWR) thread, but I always found that the SWT diagramming circa 1997 or thereabouts was quite ingenious and allowed the 'best available' (from a comfort POV) units to be used on off-peak services, thus presumably encouraging people to use off-peak.

    Off-peak, they would use 442s on as many services as possible (usually single 5WES) - not just the Weymouth/Bournemouth core route but also most of the Portsmouth Direct fasts and some of the Waterloo-Southampton 'shuttles'. Also, perhaps more than half the Basingstoke and Alton locals, and even one Waterloo-Haslemere stopper diagram out of three (called at Surbiton, Walton, Weybridge, West Byfleet, Worplesdon) would be operated by CIGs off peak, rather than the VEPs more typically associated with such routes. Presumably the rationale there was to encourage off peak travel by using the 'best available' 442 and CIG units.

    Then as peak approached a cascade would gradually take place. CIGs would move off the 'class 2' services above onto workings such as some Portsmouth fasts, with the 442s thus displaced being used to double up 442 workings towards Bournemouth and Weymouth. VEPs out of the sidings would then take the place of the CIGs on the 'class 2' services, which of course would be more appropriate stock for the peak on such services, being higher density.

    All very intricately done - though there were some oddities such as 159s being used on some Waterloo-Southampton off peaks. Not sure why that was, given there were CIGs available off peak to cover such duties.

    ISTR the South Eastern using a similar philosophy around 1986/87; for example 2 out of the 3 Tunbridge Wells locals during the day would be '1066 Electrics' CEPs, which were used to double up Hastings services in the peaks, the Tunbridge Wells locals then going over to VEPs (often 8VEP+2EPB).

    You also had more in the way of interworking at that time; the Waterloo Portsmouth via Eastleigh ('80') would typically interwork with the Solent stopper ('85') meaning shorter layovers at Portsmouth. Presumably this was dropped when the 444s and 450s came in, as it would have meant 444s on some Solent stoppers, which would have overshot many of the platforms.
     

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