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TT rule idea

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TT rule idea 19/02/2021 at 16:30 #137351
DaveHarries
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Hi all,

Not so much a wish but more of an idea.

At the moment there are 2 TT rules regarding how long before a train leaving the sim returns as its next working. They are that a train:-

- "Must appear X minutes after Y leaves the area"
- "Must appear X minutes after Y arrives or passes Z".

However it is, of course, possible for the next working to start back on time even if its previous working runs late. So, for example, on Three Bridges sim and in the current real-life WTTs:

- Train 2A46 (1630 Redhill - Tonbridge, due 1701), hereafter referred to as "Train A"
- Train 2A51 (1717 Tonbridge - Redhill, due 1750), hereafter referred to as "Train B"

Let us say that 2A46 runs 7 minutes late and arrives at Tonbridge at 1708. Under either of the two above rules, if you say that 2A51 must not appear until 16 minutes after 2A46 arrives at Tonbridge then you cause a delay of 7 minutes to 2A51's entry into the sim area when (or so I would have thought) it would be possible for 2A51 to depart Tonbridge on time after a 9-minute turnaround despite 2A46's late arrival there.

Bearing this in mind I would like to make a suggestion that a new TT rule be added which would be this:

- "Train V must not appear until X minutes after Y arrives or passes Z if train U runs more than W minutes late".

In that instance:
- U is the headcode of train B
- V is the headcode of the train A
- W is the length of the delay (ie. 7 minutes in the above example)
- X, Y and Z are as present on SimSig

Any thoughts on that or am I being silly?
Dave
Dave

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TT rule idea 19/02/2021 at 16:45 #137353
NicholasN
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What I did, with the Hereford timetable I am writing currently, is to program in the absolute minimum time needed for a realistic turn round. On Hereford that time is basically the time it would take for a driver to change ends and mobilise the train, I've allowed 5 minutes.

So in your example, the timetable writer would be better to calculate the actual minimum time needed for the train to get from the exit point (leaving the area) into Tonbridge station, a quick change ends, and back to the entry point. Which is less than the timetabled amount of time - but crucially, if it is less and the train is on time, it won't result in an early entry. So in other words the rule could just be for, say, 8-9 minutes in your example, and this would allow for a quicker turn round, but wouldn't affect the entry time if the train is on time.

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TT rule idea 19/02/2021 at 16:47 #137354
jc92
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say I'm sending a train from location A to off sim location C, via the fringe entry/exit point at B.

section times are 5 minutes A to B, 5 minutes B to C, and min turnaround time is 2 minutes.

It will therefore take a train a minimim of 12 minutes to get from B to B via C. (5+5+2). rule "train 1Z01 must not enter until 12 minutes after 1Z00 leaves the area" already covers this.

If 1Z00 had a 10 min layover at C, it will still run on time if its up to 8 minutes late as these can be recovered in its minumum 2 min layover I've worked into the rule.

no new rule is required

Last edited: 19/02/2021 at 16:48 by jc92
Reason: None given

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TT rule idea 19/02/2021 at 16:49 #137355
GeoffM
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On the rare occasion I write a TT, I put the minimum reversal time, not the scheduled time. So if a train had a 10 minute booked turnaround but can achieve it in 5 then 5 is the figure I use. But even then, this kind of rule should only be used where a single train can come back: for a big terminus with multiple possible set swaps and/or standby units, I would not use it.

[Edit] The above posts came after I started writing this!

SimSig Boss
Last edited: 19/02/2021 at 16:50 by GeoffM
Reason: None given

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TT rule idea 19/02/2021 at 18:03 #137356
phil1044
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When I write my timetables, I incorporate terminating station dwell as per the NR rules of the route document, as well as recovery time in the TT on the outward and return legs of the trains involved to work out the mimimum time for the return train to enter back onto the sim. This takes a bit longer to work out but is more accurate for each train as opposed to listing the same mins turnaround for every train on the same route.
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The following user said thank you: TimTamToe
TT rule idea 19/02/2021 at 18:38 #137357
Dionysusnu
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This confusion might be from the slightly awkward wording of the rule.
"Must appear X minutes after Y leaves the area"
actually accomplishes
"Will appear at least X minutes after Y leaves the area"
It will not force passenger trains to enter early, if that is what Dave is worried about.

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TT rule idea 20/02/2021 at 10:52 #137362
TimTamToe
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Think you're overcomplicating things Dave (is it because you hadn't had your dinner yet )

When I write my tt's, I do as JC92 and Phil have said, and works perfectly fine with the current rules.

I use Must not enter until x min after y has left area or whatever it is. Add together the time from edge of area to destination and back again and add in the min dwell according to NR - varies for which station involved to whether that is location dwell or stock :)

Gareth

Last edited: 20/02/2021 at 10:53 by TimTamToe
Reason: None given

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TT rule idea 20/02/2021 at 12:34 #137365
bill_gensheet
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A cautionary note regarding use of either of these rules .....

"Must appear X minutes after Y leaves the area"

This has a flaw in that trains leaving elsewhere than intended (say by user error or extreme measures) will still trigger the correct return train.
_________

"Must appear X minutes after Y arrives or passes Z".

This has a flaw in that not all sims report arrivals or passes at the final exit locations. As of today for example Edinburgh does, but Kings Cross does not. You can move back a location but are then open to any delay betweeen there and the actual exit.
Mantis 29685 has more about dealing with it for Kings Cross (1964 timetable).

Do I recall there was a reason that some sims could not report at exit ?

Bill

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The following user said thank you: Soton_Speed
TT rule idea 20/02/2021 at 13:50 #137369
Soton_Speed
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TimTamToe in post 137362 said:

I use Must not enter until x min after y has left area or whatever it is. Add together the time from edge of area to destination and back again and add in the min dwell according to NR - varies for which station involved to whether that is location dwell or stock
Further to this, some TTs have rules designed to model late runners being turned short of their final destination where appropriate, eg. Coventry sim where rules, similar to above, allow late running LM New Street - Northampton stoppers (2Yxx?) to be turned short (off sim) at Rugby rather than continuing to Northampton.

In Zone 6, no one can hear you scream...
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The following user said thank you: TimTamToe
TT rule idea 20/02/2021 at 14:19 #137371
TimTamToe
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Soton_Speed in post 137369 said:
TimTamToe in post 137362 said:

I use Must not enter until x min after y has left area or whatever it is. Add together the time from edge of area to destination and back again and add in the min dwell according to NR - varies for which station involved to whether that is location dwell or stock
Further to this, some TTs have rules designed to model late runners being turned short of their final destination where appropriate, eg. Coventry sim where rules, similar to above, allow late running LM New Street - Northampton stoppers (2Yxx?) to be turned short (off sim) at Rugby rather than continuing to Northampton.
Thanks Soton_Speed... I also do that for some of them. Thanks for the nudging reminder!

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TT rule idea 20/02/2021 at 14:50 #137372
postal
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TimTamToe in post 137371 said:
Soton_Speed in post 137369 said:
TimTamToe in post 137362 said:

I use Must not enter until x min after y has left area or whatever it is. Add together the time from edge of area to destination and back again and add in the min dwell according to NR - varies for which station involved to whether that is location dwell or stock
Further to this, some TTs have rules designed to model late runners being turned short of their final destination where appropriate, eg. Coventry sim where rules, similar to above, allow late running LM New Street - Northampton stoppers (2Yxx?) to be turned short (off sim) at Rugby rather than continuing to Northampton.
Thanks Soton_Speed... I also do that for some of them. Thanks for the nudging reminder!
Now if you could make rules respect decisions (rather than decisions being restricted to train TTs and actions) you could really start to have some fun!

“In life, there is always someone out there, who won’t like you, for whatever reason, don’t let the insecurities in their lives affect yours.” – Rashida Rowe
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TT rule idea 20/02/2021 at 17:45 #137380
Splodge
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Soton_Speed in post 137369 said:
TimTamToe in post 137362 said:

I use Must not enter until x min after y has left area or whatever it is. Add together the time from edge of area to destination and back again and add in the min dwell according to NR - varies for which station involved to whether that is location dwell or stock
Further to this, some TTs have rules designed to model late runners being turned short of their final destination where appropriate, eg. Coventry sim where rules, similar to above, allow late running LM New Street - Northampton stoppers (2Yxx?) to be turned short (off sim) at Rugby rather than continuing to Northampton.
That's partly why I didn't put rules in for my Piccadilly 2020 TT - most stuff going off sim would have a wide variety of options to turn round short if need be, or have recovery time at their terminus (and believe me, in the case of Northern, we can change ends and get going very quickly if we need to!)

There's the right way, the wrong way and the railway.
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TT rule idea 20/02/2021 at 18:04 #137381
headshot119
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Splodge in post 137380 said:
Soton_Speed in post 137369 said:
TimTamToe in post 137362 said:

I use Must not enter until x min after y has left area or whatever it is. Add together the time from edge of area to destination and back again and add in the min dwell according to NR - varies for which station involved to whether that is location dwell or stock
Further to this, some TTs have rules designed to model late runners being turned short of their final destination where appropriate, eg. Coventry sim where rules, similar to above, allow late running LM New Street - Northampton stoppers (2Yxx?) to be turned short (off sim) at Rugby rather than continuing to Northampton.
That's partly why I didn't put rules in for my Piccadilly 2020 TT - most stuff going off sim would have a wide variety of options to turn round short if need be, or have recovery time at their terminus (and believe me, in the case of Northern, we can change ends and get going very quickly if we need to!)
Yes, yes you do!

"Passengers for New Lane, should be seated in the rear coach of the train " - Opinions are my own and not those of my employer
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TT rule idea 20/02/2021 at 18:12 #137382
GeoffM
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bill_gensheet in post 137365 said:
A cautionary note regarding use of either of these rules .....

"Must appear X minutes after Y leaves the area"

This has a flaw in that trains leaving elsewhere than intended (say by user error or extreme measures) will still trigger the correct return train.
The rule is not flawed. The fact that something unscheduled is happening should be a clue that other things may be adversely impacted, such as use of this rule.

_________

bill_gensheet in post 137365 said:
"Must appear X minutes after Y arrives or passes Z".

This has a flaw in that not all sims report arrivals or passes at the final exit locations. As of today for example Edinburgh does, but Kings Cross does not. You can move back a location but are then open to any delay betweeen there and the actual exit.
Mantis 29685 has more about dealing with it for Kings Cross (1964 timetable).

Do I recall there was a reason that some sims could not report at exit ?

Bill
Again, the rule is not flawed. Some sims have no benefit in simulating a station on the exit, or can be too complex to simulate off-screen in any meaningful way. KISS principle by design.

SimSig Boss
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TT rule idea 20/02/2021 at 18:28 #137383
Soton_Speed
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Splodge in post 137380 said:
That's partly why I didn't put rules in for my Piccadilly 2020 TT - most stuff going off sim would have a wide variety of options to turn round short if need be, or have recovery time at their terminus (and believe me, in the case of Northern, we can change ends and get going very quickly if we need to!)
Fair point, Splodge. My very general rule of thumb is that if you are putting in values of 'X' (from OP) greater than 60 minutes, the rule is probably limiting 'real life' flexibility.

@TimTamToe My comment wasn't aimed at you specifically, more of a general point to encourage good TT writing...

In Zone 6, no one can hear you scream...
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