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SimSig: Railway Signalling Simulations

simsig.co.uk

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Re: SimSig: Railway Signalling Simulations

#21

Post by mezmor »

londons_explore wrote: post #16
dividuum wrote: post #13

Earlier quoted context omitted.

> A more advanced system would aim to have trains as close together as cars are on a freeway. https://en.wikipedia.org/wiki/European_Train_Control_System#...

This still doesn't allow train spacing of less than the braking distance. Braking distance of trains is large (due to high uncertainty in track friction), which still means trains are typically 1 minute or more apart when moving fast. As long as you have comms with the trains around, it's clearly possible to safely go less than the braking distance, as long as you can be sure of the behaviour of the train ahead, even…

Aren't braking distances so large because of the massive amounts of mass in motion? Inertia, etc. Even high certainty of track friction wouldn't change that.

Also, I don't think it's ever safe to be closer than braking distance because the bahavior of the train ahead is never guaranteed. There's always a chance somebody parks their car on a rail crossing or some other sudden stopping-event occurs.

Re: SimSig: Railway Signalling Simulations

#22

Post by euroderf »

secondcoming wrote: post #19
londons_explore wrote: post #12

Railway signalling IMO is an area where a little research could dramatically increase the throughput of the railway network with a rather low cost. Todays railways mostly use fixed block signalling. Expensive and unreliable equipment ensures that there is only one train on each 'block' of railway track at the same time. That forces trains to be at least 1 or 2 blocks apart, which are frequently multiple miles long. E…

> Crashes would be avoided by having every train know about the train ahead and behind Isn't this a block system? > it is not allowed to slam the brakes on if there is a train right behind you So if we have three trains in close succession and the first derails or loses power, the second is not allowed stop because there's a train behind it? > Trains are usually 10's of minutes apart, or at least 1 minute apart even…

AFAIK the underground is not beset with blockages caused by fallen trees and stalled automobiles.

Re: SimSig: Railway Signalling Simulations

#23

Post by trainyperson »

londons_explore wrote: post #12

Railway signalling IMO is an area where a little research could dramatically increase the throughput of the railway network with a rather low cost. Todays railways mostly use fixed block signalling. Expensive and unreliable equipment ensures that there is only one train on each 'block' of railway track at the same time. That forces trains to be at least 1 or 2 blocks apart, which are frequently multiple miles long. E…

Much of what you’re describing (besides the live hitching and unhitching) is made possible by Communication-Based Train Control (CBTC) [see link below]. This has been implemented in many rail systems globally, mostly urban rail. It helps reduce headways a lot. However:

1. It’s not just a software problem - installing the hardware is time-consuming and expensive. The engineering requirements are much stricter when human lives are at stake so you can’t just strap on a radio to each train. You still need additional infrastructure along the tracks to manage communications.

2. There are other limiting factors in reducing headway - having enough trains and having enough train operators. Somewhat easier to solve perhaps but still costly and non-trivial.

———

https://en.wikipedia.org/wiki/Communications-based_train_con...

Re: SimSig: Railway Signalling Simulations

#24

Post by secondcoming »

euroderf wrote: post #22
secondcoming wrote: post #19

Earlier quoted context omitted.

> Crashes would be avoided by having every train know about the train ahead and behind Isn't this a block system? > it is not allowed to slam the brakes on if there is a train right behind you So if we have three trains in close succession and the first derails or loses power, the second is not allowed stop because there's a train behind it? > Trains are usually 10's of minutes apart, or at least 1 minute apart even…

AFAIK the underground is not beset with blockages caused by fallen trees and stalled automobiles.

It does have its fair share of 'people under a train' and people preventing doors from closing.

Re: SimSig: Railway Signalling Simulations

#25

Post by londons_explore »

pixiemagic wrote: post #20
londons_explore wrote: post #16

Earlier quoted context omitted.

This still doesn't allow train spacing of less than the braking distance. Braking distance of trains is large (due to high uncertainty in track friction), which still means trains are typically 1 minute or more apart when moving fast. As long as you have comms with the trains around, it's clearly possible to safely go less than the braking distance, as long as you can be sure of the behaviour of the train ahead, even…

What happens if there's some other reason to brake, such as an unreported fallen tree on the line ahead?

You can still brake - you just need (automatic) agreement of all trains behind you to do so.

You aren't allowed to brake 'as much as possible' anymore - instead the best you can achieve is 'the best the worst of the trains behind me can achieve'.

Re: SimSig: Railway Signalling Simulations

#26

Post by bluGill »

londons_explore wrote: post #18
p_l wrote: post #15

Earlier quoted context omitted.

Moving block systems are not really new, they just aren't distributed widely.

Moving block doesn't allow trains to get closer together than the braking distance. This would.

There is good reason they don't do that: trains derail once in a while, your plan means the following train will hit that train and so the accident is worse.

Part of the answer to that is better track maintenance. However that isn't a perfect answer and so we need larger gaps.

Note that cars on the freeway are normally much closer together than is safe as well. If cars maintained a safe following distance we would need 5 times as many lanes. (you know the massive freeways in Huston that urbanists like to show as bad: that is about the correct size of freeway for Des Moines, Huston needs many more if they want to be a car oriented city)

Re: SimSig: Railway Signalling Simulations

#27

Post by cmul »

For German speakers: https://www.estw-simulator.de/index.html https://www.estwsim.de/cms/index.php

These have been around for a while and quite closely mimic (slightly older) German signalling specifications for signaller interfaces.

My company builds such systems as test and demonstration systems for real railway projects with respective functional safety constraints. If you're interested to learn more about the signalling infrastructure in Europe or Germany, feel free to ask.

Re: SimSig: Railway Signalling Simulations

#28

Post by gsck »

chin7an wrote: post #17
gsck wrote: post #10

Earlier quoted context omitted.

Pretty sure the developers of Factorio made a train game based around the train system in Factorio. Can't for the life of me remember its name but it looks rather good

Is it Sweet Transit? The about section mentions that the developer was part of Factorio. Edit to add link - https://www.sweettransitgame.com/

Yes, that's the one. Never played it, but from my understanding its effectively just the train system lifted out of Factorio with a game built around it.

Re: SimSig: Railway Signalling Simulations

#29

Post by Cthulhu_ »

londons_explore wrote: post #12

Railway signalling IMO is an area where a little research could dramatically increase the throughput of the railway network with a rather low cost. Todays railways mostly use fixed block signalling. Expensive and unreliable equipment ensures that there is only one train on each 'block' of railway track at the same time. That forces trains to be at least 1 or 2 blocks apart, which are frequently multiple miles long. E…

This puts a LOT of faith / confidence in and requirements on hardware and communications; while it all sounds good on paper / in your head / in theory, there's going to be a ton of practical issues that someone more qualified than me will be able to list.

It's got the same energy as Musk advocating for Hyperloop and/or car tunnels by amortizing all the practical, cost, engineering, legal and safety considerations. Sure, in theory a maglev train in a vacuum tube is super fast, but in practice building the infrastructure is prohibitively expensive and there's not a big enough market for it.

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