Seems similar to Transit's approach: https://blog.transitapp.com/go-underground/

Meanwhile, other engineers are working on reducing the vibrations.

I wonder what app has allow location on all the time and is feeding them their data

"Acquired by Trainline in 2023, Signalbox works with organisations across the rail ecosystem to improve customer information and operational awareness."

https://www.signalbox.io/news/southeastern-launches-track-my...

So, we don't know if this is the case, but one way to do this is not to ask the phones but the cells. The mobile network has to know where the phones are by cell; the cells are often small relative to the speed of the train; there are also cells installed specifically to improve service on trains, or provide a base station to the train wifi, or for communications to railway staff.

If you get a bunch of phones switching cell near simultaneously, you can tell that a train movement across the cell boundary has probably happened. Then correlate that with the other data feed about train blocks, and bob's your uncle.

Only about 50% of trains have wifi: https://www.businesstravelnewseurope.com/Ground-Transport/UK... ; but it's easy to imagine getting the mobile hotspot on the train to share its GPS location as well.

You're missing the fact that the system is also divided into explicit signal blocks and those blocks do report train presence to a centralized system[1]. I am not certain if they want to share that information, but if someone got serious about building a system like signalbox I'd expect that NetworkRail would either offer their data, a degraded version of their data on a lag for security reasons, or consider those security reasons so serious that they'd attempt to prohibit deriving that data from cell signals.

1. Mostly, some signal blocks are still entirely manually managed but, IIRC, at this point those manually managed segments are low traffic areas where only one train is allowed into the block group at a time even if the old signal management systems would allow multiple trains.

Before he was hired by a San Diego-based defense contractor, my maternal grandfather worked on the railroads as a pipe-fitter, and he designed and built for me a high-quality Lionel model railroad in his home, before he passed away. It even had those little smoke-generating tablets that you could drop into the smokestack. I was only six years old.

This year, I was curious about whether I could track freight trains in my region or nearby, in real-time, and perhaps more details like what sort of cars were linked in the train, how many locomotives, what sort of freight they were carrying, etc.

After a few fruitless searches for this tracking info, I realized that the same info that would be "recreational" for me would be "operationally valuable" to any domestic terrorist cell or motivated insurrectionist, as well.

Trains derail all the time, we are told, and trains are robbed blind increasingly often, so I am sure there is some sort of illicit/underground tracking that takes place already, but for now, I must content myself with noticing trains using my own eyes and ears. The freight line next door is inhibited from sounding their horns except in emergencies. And thankfully, I find freight-train and light-rail noise to be calming and soothing, even at 3:30am...

That data is in fact made publicly available by Network Rail: https://wiki.openraildata.com/index.php/TD

though interpreting it isn't the easiest thing in the world...

That is fair - though at least they've well defined their standard. It'll be easier than trying to parse that data out of HTML with regexes at least.

Few questions, wonder if anyone knows the answers:

1. So it's Trainline on a persons phone that is tracking this info and using it to enrich this service? I use Trainline and didn't know it was doing that, but I do have location permissions on because I was told that powered the search picker when I started using the app.

2. What did they use _before_ Trainline? Or was Trainline selling user location data to them?

I think you're misunderstanding what they are saying. They don't use background location data, but they do use your current location data. Try the "Find My Train" demo on their site - it asks for location permission.

Or their API - it also expects device location data:

> At a minimum, requests to the detect endpoint _must_ contain a device's location measurement. Additional fields can be included where available to improve the accuracy of the returned results as outlined below.

https://docs.signalbox.io/docs#/operations/Detect_detect

wait - so you think that the map is made up of people who are all sitting on that website using the Find My Train demo?

I think you are missing the point - what is collecting data on all those trains.

No, live train data in the UK is already publicly available, e.g. see https://www.opentraintimes.com/

This is matching your phone's location to the already public train data.

> This is matching your phone's location

But what is getting that?

You are giving it to them. That's why the demo asks for your location permission, and that's why the API expects location info.

"You" here means another app that integrates their API (or you as an individual using the demo on their website). How the other app gets it is up to the other app - ideally it also just queries it directly and requires location permission.

so an empty train does not show up?

Not sure how you came to that conclusion. An empty train would still exist in the live train data. It does not depend on mobile phones, but on rail signals and other such tracking built into the rail infrastructure.

of course, sry, I didn't read the descriptions. Thanks for clarification!

Does a train exist if you are not on it?

The location of the train comes from trackside sensors and is available as a free API. It doesn't give actual lat/lon – it only shows when it went past a particular checkpoint. The part that needs location permission is the one that works out which train you are on. It doesn't use that to produce the main map, it's just to work out which train you are likely to be on.

Some TFL stations and trains have WiFi that has tracking in the ToS.

The relatively benign kind though. They use it to figure out congestion and station use etc

It works fairly well empirically: my 7yo likes to watch trains and we regularly use this map to know when to expect one to pass. Not perfect, but pretty good