Islineclear3_1
Established Member
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?
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.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.
Also trains aren't usually subject to maximum working hours or mandatory rest breaks
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.
Thanks for explaining. I know diagramming is very complex and has to take account of many factors
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.
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.
Ah yes but I have heard of trains being "out of miles" where exams, overhauls fall due
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.
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!
I know this isn't the question you asked, but I once posted about the Short Term Planning timetable planning, which is related, and hopefully gives an idea of how complex it is with the considerations that need to be thought of:
https://www.railforums.co.uk/threads/train-planners.59171/#post-963312
Pre Thameslink the GN fleets at Hornsey were as follows.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.
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.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?
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.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.
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.