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Entry delay is entrance is blocked

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Entry delay is entrance is blocked 06/10/2022 at 20:11 #148282
rfw
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I've experienced this phenomenon when writing a stupidly busy timetable, when an entrance is blocked by a previously entered train and another train is scheduled to enter before the entrance headway is clear the SimSig will 'park' the train for a period of time before re-trying to enter it.

Does anyone know what this delay is or if it is a random time in a range.
If there are multiple trains parked for entry from the same entrance, do they get retried in any particular order or is it whose park timer depletes first?


And I assume the area that is considered the entrance headway varies from sim entrance to sim entrance

The train now standing on platform 2, should be on the rails
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Entry delay is entrance is blocked 06/10/2022 at 20:51 #148283
GeoffM
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I'm not sure what you mean. There's certainly no "parking". Can you attach a save?
SimSig Boss
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Entry delay is entrance is blocked 07/10/2022 at 13:32 #148290
clive
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There's a lot of processing before a train is queued for entry (for example, there must be no rules holding the train back). Eventually the core code and the simulation data between them will have selected an actual entry point (not necessarily the one in the timetable) and an actual entry time (after allowing for things like delays).

Each entry point has three parameters that are important here: the headway time, the queue length time, and the entry route (a sequence of track circuits). The headway time is the minimum time between trains entering, no matter what. The entry route must all be unlocked and unoccupied for a train to enter.

The queue length time is perhaps the least obvious item. This is designed to simulate the fact that an entry point might be on plain track and so approaching trains can't be re-ordered. The value is decided by the simulation author. For something like a goods yard, it would be zero. But for an entry point that's 5 miles of plain track after the last loop or junction or other place to hold trains, it might be 200 or 300 or 400 seconds (depending on what the author thinks the average train speed will be).

Once the core code decides that a train is definitely going to enter, it's put at the end of the entry queue for that entry point. This queue is *never* reordered; trains always enter in the order they joined the queue.

The front train on the queue will enter as soon as:
* it's been on the queue for at least the queue length time;
* the entry route is clear;
* the previous train to enter did so at least the headway time earlier; and
* any sim-specific controls on the entry point allow it.

This is a simplified description, but it should give you the general idea.

(Any developers reading this; look at the ENT section of the manual for more details.)

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The following user said thank you: rfw
Entry delay is entrance is blocked 08/10/2022 at 14:51 #148299
rfw
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GeoffM in post 148283 said:
I'm not sure what you mean. There's certainly no "parking". Can you attach a save?
Save attached, and after reading what clive had said, I can now see that whilst trains are 40 minutes late entering because I'm sending them more frequently than can be supported by the entry conditions, they are entering in sequence and obeying.

Perhaps park was the wrong term, queue is better to describe what actually happens. But queue suggests that a strict first-in-first-out order and at the time of my original post I wasn't sure if this was the case or if the loader used some other method for entering trains from a pool of eligible entries.

Thankyou for putting up with & answering my annoying questions about obscure technical details

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The train now standing on platform 2, should be on the rails
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The following user said thank you: GeoffM
Entry delay is entrance is blocked 08/10/2022 at 22:38 #148306
clive
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Something I perhaps didn't make clear is that, when I wrote "There's a lot of processing before a train is queued for entry", this processing can alter the order of trains. Indeed, it can delay trains, cancel them, send them to different entry points ... all up to the diabolical ingenuity of the sim developer.

It's only when a train gets put in the entry queue that the order is fixed.

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The following user said thank you: rfw
Entry delay is entrance is blocked 09/10/2022 at 12:15 #148310
rfw
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That makes sense from what I've seen. You get the incident & rule delays on a train entering. The alternative entry also makes sense as in if your fast lines are blocked, they could enter on the slow. I've not seen the cancel functionality before, and I'm not sure when that'd actually get used, perhaps on a shuttle route into another (un-controlled) box, and delays on the outbound are such that you skip a trip to recover time. I understand why the to cancel option is there and also why you don't see it very often.


clive in post 148306 said:
diabolical ingenuity

The more I look, the more I see how many clever systems are in place to logically handle all the possible simulated troubles a could be seen. And the more I see that our wonderful sim & core developers indeed possess that diabolical ingenuity to keep us on our toes.

The train now standing on platform 2, should be on the rails
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