Draft graph for TT 4.1.4

Right I've had a brief opportunity this evening to look at the trips you are querying.

I've now ensured that all trains are at least 2 minutes apart at Brixton, in both directions. Most changes were +/-30sec, a few slightly more than that.

I now have about 18 Walthamstow, 8 Brixton and 22 Seven Sisters potential instances of platforms being scheduled for two trains simultaneously.

For Walthamstow 1, Walthamstow 2, Brixton 1 and Brixton 2, and Seven 4, how would I go about calculating the minimum time between departure and next arrival in the same road, taking into account signal spacing, point throw time etc all under ARS? Or would it be easiest to just signal a few trains at half-speed simulation, note the times and use those measured values?

If there's a train every 90 second do you actually need a timetable? To what extent do the trains keep to the timetable in reality?

Peter

If there's a train every 90 second do you actually need a timetable? To what extent do the trains keep to the timetable in reality?

Peter

Peter Bennet in post 158651 said:

If there's a train every 90 second do you actually need a timetable? To what extent do the trains keep to the timetable in reality?

Peter

For customers no - it is why apart from on the Metropolitan Line only first and last trains are published. The system is meant to be "turn up and go" though obviously there are many exceptions to this. The Circle Line runs at 10-minute frequencies, which is way outside of people's perceptions of a frequent service when compared to the Victoria Line.

In reality yes most definitely. It is one of the Line Controller's main responsibilities to keep the line running on time to the timetable. You have to have a timetable or you would very quickly have disorder. It governs when a driver should depart a station. It relates to each driver's duty and where they should be and when. It might all seem like a random shovelling of trains down the pipe (and sometimes such lines as the Vic can certainly seem it even to those in control) but the timetable has all sorts of things relating to it that keep everything moving as it should.

For historical technical reasons LU trains are numbered in octal (base 8, no 8 or 9). Pointless using another 'bit' for that.

Train numbering for all LU timetables starts off initially with everything running in order and sequentially. Service patterns may then shuffle this ordering. Some lines have "self-contained" numbering systems for each service that is run.

Then, over time, this numbering is further revised when a timetable is reviewed etc. The question of why certain numbers are used can be down to many reasons. It may be that a train starting out in the evening peak ends up stabling that night in a certain place, and the number makes it stand out. It may also have a different number because, for instance, it actually only runs for a few hours then stables back in the depot.

Not only does the use of different numbers assist those trying to recover the service (as a controller it's handy to have those numbers that stand out) but from a rolling stock / depot perspective it can also dictate which physical trains are allocated to which number at the start of the day. As an example, a train due an exam on Tuesday morning, may start on Monday morning as a train which stables that night in the depot. If it is allocated to a train which "out-stables" at Brixton or Walthamstow, then by Tuesday morning it could be overdue exam and not able to run in customer service.

So the numbering may look random and it may look like certain numbers could be re-used, but there is always another reason in the background why the number itself is chosen.

metcontrol in post 158762 said:

Train numbering for all LU timetables starts off initially with everything running in order and sequentially. Service patterns may then shuffle this ordering. Some lines have "self-contained" numbering systems for each service that is run.

Then, over time, this numbering is further revised when a timetable is reviewed etc. The question of why certain numbers are used can be down to many reasons. It may be that a train starting out in the evening peak ends up stabling that night in a certain place, and the number makes it stand out. It may also have a different number because, for instance, it actually only runs for a few hours then stables back in the depot.

Not only does the use of different numbers assist those trying to recover the service (as a controller it's handy to have those numbers that stand out) but from a rolling stock / depot perspective it can also dictate which physical trains are allocated to which number at the start of the day. As an example, a train due an exam on Tuesday morning, may start on Monday morning as a train which stables that night in the depot. If it is allocated to a train which "out-stables" at Brixton or Walthamstow, then by Tuesday morning it could be overdue exam and not able to run in customer service.

So the numbering may look random and it may look like certain numbers could be re-used, but there is always another reason in the background why the number itself is chosen.

Hmm. When you developed V4.1.3, did you take the run numbers from the WTT or were they created fresh for Simsig?

Sets 201, 202, 203, 205 and 206 all start and end at the exact same locations, so for operational/maintenance requirements they'd need to be swapped over adhoc when those sets visit Northumberland on crew shuttles during the interpeak period; that rules out the flagging of sets for multi-day maintenance purposes. The AM/PM or short run explanations don't match the rosters as provided, since V247 and V250 are PM-only but V271, V272, V273 are mixed in with the others. If V227, 247 and V250 had unique number sequences and the others were consecutive it'd make sense. Maybe they were planned that way originally, and the form/formbys got shuffled around sometime between when the schedule was initially written and the 2009 version you'd used? i.e. perhaps V250 was the AM peak only roster, and V271, V272, V273 were PM peak only rosters? That could also explain the lack of V260-V267.

The only other reason I can think of is that perhaps it's related to which road/s the sets start or end at, at Northumberland? e.g. normal sequence roads 48-49, others 50-51 or something like that. I'd need to check if that matches the data, and it would need to be explained by specific facilities available in different parts of the yard e.g. light or heavy maintenance, wash facilities etc. distinct from regular stabling.

The reason I'm asking is because the software I have for generating graphs needs a specific number of rosters in order to display them properly. Ideally it'd be a multiple of 12, but 13 is the next-best option, so I'm trying to reduce the roster of 40 sets to 39. (38 sets, though theoretically possible, would be significantly worse for me to model.)

The general reasons have been given in some considerable detail by metcontrol, but specifics of the kind you are after may very well be lost in time and may come down to little more that a holdover from an even earlier time or simple whim.

However if you want an accurate timetable that reflects the real timetable that did run and which metcontrol does have access to you can't play around with the numbering and will have to accept it for what it is. If you want to write a fantasy timetable very closely modelled on the real thing but made perfectly regular according to your graphing tastes you should probably commence that project at once.

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The general reasons have been given in some considerable detail by metcontrol, but specifics of the kind you are after may very well be lost in time and may come down to little more that a holdover from an even earlier time or simple whim.
<snip>

I'll be honest I still don't really get the point of this graph malarky.

I just enjoy the original tt, that is probably 99.9% accurate of what was at the time the timetable is based on. I'm always grateful for the knowledge of @MetControl that enabled it to be produced.

At the end of the day LU like many companies in various sectors around the world, have things for a reason. It may not make sense to those on the outside world, but is fundamental to the logistical smooth running of the company on a day to day basis.

I'll be honest I still don't really get the point of this graph malarky.