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Train speed after clearing signals.

You are here: Home > Forum > Simulations > Released > King's Cross > Train speed after clearing signals.

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Train speed after clearing signals. 28/03/2018 at 19:51 #107071
bugsy
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1766 posts
I would like to know if the circumstances that I describe below would actually occur in reality.

I have train 1H03 approaching signal 597 on the Down Fast at Welwyn Garden City. I am manually controlling this signal and the next two signals (607 and 619), but owing to other activities elsewhere in the sim, I have failed to clear them after the preceding train. I notice this and quickly clear them when 1H03 is travelling toward signal 597 at approximately 67 mph. To my disappointment, 1H03 continued to brake until it’s speed was 40 mph. This seems unnecessary to me. After all, it now has a clear path.
I would be interested in comments and an explanation.

Thanks
Bugsy

See attached a screenshot.


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Everything that you make will be useful - providing it's made of chocolate.
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Train speed after clearing signals. 28/03/2018 at 19:56 #107075
GeoffM
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6376 posts
The train won't accelerate / stop braking until it is in sight of the signal. Without in-cab signalling with continuous updates (certainly not here!), this is indeed how trains behave in real life.
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Train speed after clearing signals. 29/03/2018 at 08:46 #107083
kbarber
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I wonder if one of the issues is sighting distances.

Correct me if I'm wrong: doesn't Simsig assume a signal is visible at 200m but not before?

In real life, there are significant stretches of the ECML where it's possible to see the next two signals with ease; in that case a driver would, of course, start to accelerate as soon as the signal ahead steps up. But there are also places where curvature or obstructions limit visibility. Unless devs have full information on the sighting distance for every signal (and the time and inclination to input it... rather them than me on a big sim like this!) it is impossible, in practical terms, to offer perfect simulation of real life.

I guess it's one of the few compromises we have to put up with.

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Train speed after clearing signals. 29/03/2018 at 09:06 #107084
JamesN
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kbarber in post 107083 said:
I wonder if one of the issues is sighting distances.

Correct me if I'm wrong: doesn't Simsig assume a signal is visible at 200m but not before?

In real life, there are significant stretches of the ECML where it's possible to see the next two signals with ease; in that case a driver would, of course, start to accelerate as soon as the signal ahead steps up. But there are also places where curvature or obstructions limit visibility. Unless devs have full information on the sighting distance for every signal (and the time and inclination to input it... rather them than me on a big sim like this!) it is impossible, in practical terms, to offer perfect simulation of real life.

I guess it's one of the few compromises we have to put up with.
Default sighting distance is 300m - this is customisable by the sim developer where true values are known.

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Train speed after clearing signals. 29/03/2018 at 10:51 #107086
clive
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JamesN in post 107084 said:

Default sighting distance is 300m - this is customisable by the sim developer where true values are known.
To clarify: it can be overridden for any single signal or, independently, the default can be changed.

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Train speed after clearing signals. 29/03/2018 at 10:53 #107087
clive
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kbarber in post 107083 said:

In real life, there are significant stretches of the ECML where it's possible to see the next two signals with ease;
I learned about four-aspect signalling as a child by standing on the platform at Leigh-on-Sea and seeing about six signals ahead. (At least, it felt like six in memory; it may have been less.)

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Train speed after clearing signals. 30/03/2018 at 09:38 #107101
kbarber
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clive in post 107087 said:
kbarber in post 107083 said:

In real life, there are significant stretches of the ECML where it's possible to see the next two signals with ease;
I learned about four-aspect signalling as a child by standing on the platform at Leigh-on-Sea and seeing about six signals ahead. (At least, it felt like six in memory; it may have been less.)
Could well have been Clive. I recall when I became Station Supervisor at Barking, the Station Manager suggested I have a cab ride to get a feel for the patch. (The rigours of learning a new job :-) ) There were stretches where multiple signals were in sight. The really interesting stretch was Fenchurch - Stepney East (now renamed Limehouse), where the signals were 200yd apart and the AWS ramp for each signal was at the signal in rear. I think even at the low speeds authorised along there, there were multiple double-yellow sequences.

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