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SimSig: Railway Signalling Simulations

simsig.co.uk

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Re: SimSig: Railway Signalling Simulations

#51

Post by bluGill »

londons_explore wrote: post #35
Cthulhu_ wrote: post #29

Earlier quoted context omitted.

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. Su…

The market for people transport is huge. Imagine the cost of all apartments in manhattan @ $3000/sq foot. Now imagine the cost of the same apartments built in upstate new york @ $250/sq foot. A transit provider who can get people from a house in a rural area to manhattan in 15 mins can pocket that difference, which is huuuuge .

> Imagine the cost of all apartments in manhattan @ $3000/sq foot.

Does such a thing exist? A tiny bathroom is 25sq feet - or $75000. That just seems too much.

Zillow lists studio apartments in Manhattan for $3000-$5000/month. They also list apartments in New Jersey for $250/month just 30 miles away (1 hour drive to Manhattan according to maps). At that distance we don't need fancy hyperloop, we just need good higher speed rail service easially done with existing technology. (I have no idea how the apartments compare other than price - likely the Manhattan ones are much nicer for the same amount of space and the New Jersey neighborhood may be unsafe)

Re: SimSig: Railway Signalling Simulations

#52

Post by corobo »

londons_explore wrote: post #40
garaetjjte wrote: post #38

Earlier quoted context omitted.

If one train derails for some reason, then every single train on the line crashes in the greatest pileup ever. Great.

Thats already the case for carriages within a train.... And people are fine with it. We're also fine with the risk of a derailment onto a neighbouring track with traffic going the opposite direction. We could have tech which detects that, but we do not.

A train derailing onto another track would be a hell of a derailment

Take this incident for example https://www.bbc.co.uk/news/uk-england-surrey-68466494

Imagine that then resulted in "the following train then slammed into the derailed train, having been unable to stop in time"

Re: SimSig: Railway Signalling Simulations

#53

Post by danhor »

jcranmer wrote: post #39
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…

There are two things that control the ruling headway on a subway system. The first is platform dwell time. While a train is stopped at a station, you cannot let another train move into its position as if it was going to start moving on schedule, because it's actually quite likely that it won't . Given that platform dwell time is about 30s, and taking into account time needed to decelerate and accelerate to/from a sto…

> and heavily reverse-branched systems like the DC Metro or NYC Subway struggle to make even 20TPH.

I find this really interesting that is seems to be the limit for "big-boy" complicated subway systems, while there are many very complicated smaller systems that achieve much more. For example, a lot of the german Stadtbahn systems run somewhat long trains (up to 80m), run using conventional signalling systems underground (so not on-sight, which would allow for a much higher throughput). Naively I'd assume the tram-style segments and frequent at-grade crossings would make this much worse, but apparently not.

For example, Stuttgart (https://download.vvs.de/Stadtbahn_Liniennetz.pdf, https://gleisplanweb.eu/show.php?Map=Stuttgart&Index=1&Heigh...) currently runs 27 tph between Stadtbibliothek and Olgaeck, with plans to run 30 tph without any upgrades, and 30 tph between Staatsgalerie and Stöckach (additionally even running the U11 for events) without any significant issues and quite a complex network with many flat junctions outside the underground sections. The DC Metro has much less complicated branching/reverse-branching patterns.

Re: SimSig: Railway Signalling Simulations

#54

Post by Cthulhu_ »

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/

It even looks like the rail assets were lifted straight from Factorio. I mean if it's all above board it's fine - Factorio's train system is really good.

That said, they're also giving it major updates/overhauls in the upcoming update, so this one would be falling behind if there's no good relationships between the two.

Re: SimSig: Railway Signalling Simulations

#55

Post by rjmunro »

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?

As soon as one train brakes, the train behind should automatically brake. The separation distance can be maintained. The problem is if the first train hits an object or derails, this might cause it to slow down faster than the brakes would have done, and the following train may not have time to stop.

Re: SimSig: Railway Signalling Simulations

#56

Post by rjmunro »

corobo wrote: post #52
londons_explore wrote: post #40

Earlier quoted context omitted.

Thats already the case for carriages within a train.... And people are fine with it. We're also fine with the risk of a derailment onto a neighbouring track with traffic going the opposite direction. We could have tech which detects that, but we do not.

A train derailing onto another track would be a hell of a derailment Take this incident for example https://www.bbc.co.uk/news/uk-england-surrey-68466494 Imagine that then resulted in "the following train then slammed into the derailed train, having been unable to stop in time"

It happened at the Clapham Junction rail crash in 1988: https://www.bbc.co.uk/news/uk-england-london-46509473

A total of 3 trains were involved.

Re: SimSig: Railway Signalling Simulations

#57

Post by corobo »

londons_explore wrote: post #31
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…

> 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? The second is allowed to follow the 'train ahead derailed' plan, which presumably will involve stopping at a rate that the third train can also achieve. If comms is maintained during the event, new plans can also be made that are maybe better (eg. maybe try to brake…

Instead of a derailed train and a couple delayed trains you now have a derailed train and a couple of trains with flat wheels that also need clearing up (assuming they avoided slamming into each other)

Definitely not sold on the "let's chuck out the failsafe method of railwaying" idea, haha

Re: SimSig: Railway Signalling Simulations

#58

Post by corobo »

rjmunro wrote: post #56
corobo wrote: post #52

Earlier quoted context omitted.

A train derailing onto another track would be a hell of a derailment Take this incident for example https://www.bbc.co.uk/news/uk-england-surrey-68466494 Imagine that then resulted in "the following train then slammed into the derailed train, having been unable to stop in time"

It happened at the Clapham Junction rail crash in 1988: https://www.bbc.co.uk/news/uk-england-london-46509473 A total of 3 trains were involved.

Oh wow, I was 6 months old when that happened. (36y/o now)

Pretty decent track record if that's the most recent example!

Upping the ante: how much worse would that have been if there were trains following closer than braking distance in both directions.

Special note that the train derailed so severely in this incident after colliding with a train stopped in front of it.

I'm even less of a fan of OP's "braking distance shmaking distance" proposal with this example of why it's a bad idea!

Re: SimSig: Railway Signalling Simulations

#59

Post by cmul »

secondcoming wrote: post #24
euroderf wrote: post #22

Earlier quoted context omitted.

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.

Which is why ATO (automatic train operation) is most often found in subways where the platforms can be equipped with gates to keep passengers out until a train has stopped safely. Suicide by train and level crossings are a nightmare in risk management for railway safety, hence also (new) high speed tracks are usually planned without any intersections with roads or paths, at respective additional costs.

Re: SimSig: Railway Signalling Simulations

#60

Post by loa_in_ »

8372049 wrote: post #8
fragmede wrote: post #6

Earlier quoted context omitted.

For people that want a railway simulator that includes game mechanics to drive a lot of complexity, try Factorio.

Or OpenTTD https://www.openttd.org

Especially a fork called JGR's patchpack, featuring programmable signals and so much more.
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