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Timetabling Braking Performance

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AlfaPendular

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I have been reading some very interesting discussions all over the forum, very nice posts and some nice tips.

I think there might be someone that can help me in a project.

I am doing some railway research, more precisely with braking problems related with low-adhesion. I am working with some partners to create a solution for the problem, but I keep getting stuck on a subject we don't really have great expertise on.

I am trying to understand how the rolling stock performance is used to create the timetable for a route, especially the train braking capacity.

Does anyone have some tips on how this is accounted on the route timetable?

I can provide some more details if needed. But we can start with something simple:
Who is responsible to access if the rolling stock is capable of fulfilling the requirements? TOC's, NR...

Sorry if the post is not on the correct section, and thank you for any help
 
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The Planner

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When it comes to performance modelling the braking figures are/were 0.67m/s² for HST, 0.78m/s² for EMU/DMU and 0.447m/s² for freight. Pretty sure acceleration is pegged at 0.588m/s² though they might have changed.
 

AlfaPendular

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29 Jul 2019
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Location
West Yorkshire
When it comes to performance modelling the braking figures are/were 0.67m/s² for HST, 0.78m/s² for EMU/DMU and 0.447m/s² for freight. Pretty sure acceleration is pegged at 0.588m/s² though they might have changed.
All year round? The only input is the type of rolling stock considered?

Thank you for the answer
 

The Planner

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All year round? The only input is the type of rolling stock considered?

Thank you for the answer
Yes, you only have one set of running times for each type of rolling stock based on its capabilties, linespeed, gradient of track etc.. adhesion plays no part. For leaf fall timetables the timetable will be altered by the use of adjustment allowances, normally specifed by the operator and even then they won't be massively scientific.
 

Wilts Wanderer

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I would say that braking performance is one of the areas where timetabling practice has not kept up with the changes created by modern professional driving techniques.
 

Ianno87

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I would say that braking performance is one of the areas where timetabling practice has not kept up with the changes created by modern professional driving techniques.

Generally, historic SRTs have been kept (since changing them would break the timetable) whilst driving has become more defensive.
 

steve_brown

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When it comes to performance modelling the braking figures are/were 0.67m/s² for HST, 0.78m/s² for EMU/DMU and 0.447m/s² for freight. Pretty sure acceleration is pegged at 0.588m/s² though they might have changed.

These are indeed the defaults to be used if more accurate data is not provided (e.g. by TOCs). Recent studies have shown that actual observed braking rates are typically in the range 2%g to 6%g, so approximately 0.2 m/s² to 0.6 m/s², and this has been noted for more recent studies.

I would say that braking performance is one of the areas where timetabling practice has not kept up with the changes created by modern professional driving techniques.

This has been true until very recently. Current best practice in calculating new "Technical Running Times" is to calibrate the simulation model against observed running data for a current type of traction, and then to apply the same set of braking assumptions to any new traction on the same route. Modern simulation tools can also explicitly model Professional Driving policies.
 

The Planner

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These are indeed the defaults to be used if more accurate data is not provided (e.g. by TOCs). Recent studies have shown that actual observed braking rates are typically in the range 2%g to 6%g, so approximately 0.2 m/s² to 0.6 m/s², and this has been noted for more recent studies.

This has been true until very recently. Current best practice in calculating new "Technical Running Times" is to calibrate the simulation model against observed running data for a current type of traction, and then to apply the same set of braking assumptions to any new traction on the same route. Modern simulation tools can also explicitly model Professional Driving policies.
Mr Brown of RWA fame? I've not dabbled in those dark arts for a little while but it was always a pain to try and simulate approach control. Getting the model right first is always the issue!
 

steve_brown

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Mr Brown of RWA fame? I've not dabbled in those dark arts for a little while but it was always a pain to try and simulate approach control. Getting the model right first is always the issue!

RWA was a few years ago now! But yes, that's me. Still dabbling in said dark arts, and have some new toys to play with now.
 

AlfaPendular

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Location
West Yorkshire
These are indeed the defaults to be used if more accurate data is not provided (e.g. by TOCs). Recent studies have shown that actual observed braking rates are typically in the range 2%g to 6%g, so approximately 0.2 m/s² to 0.6 m/s², and this has been noted for more recent studies.

Thank you very much for your input.
The results from the studies make it look like they are not compliant with the default values said on the previous posts, at least for passenger trains. So these values account for all the brakes to standstill, or just platform approaches?

This has been true until very recently. Current best practice in calculating new "Technical Running Times" is to calibrate the simulation model against observed running data for a current type of traction, and then to apply the same set of braking assumptions to any new traction on the same route. Modern simulation tools can also explicitly model Professional Driving policies.

This is good news. Is the software some in-house product, or can be used externally?

We are trying to solve the problems with brake rate limitations due to adhesion, by increasing the minimum guaranteed brake rate in all adhesion conditions. The objective is to eliminate the Autumn timetable for a specific case. This value (minimum guaranteed brake rate) seems to vary a bit depending on the route, based on the simulation. Correct?
 
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