I don't want to be negative here, just asking out of curiosity. Does anyone actually use apps/services like this? Why would it be useful?

Normally when I want to get somewhere I just use local public transport navigation app which calculates the route and shows me estimated time of when my tram or bus arrives (taking into account its GPS data). Why would I need to know live position of every vehicle in the city?

Nevertheless, cool project!

I use the dutch version of this (OVInfo: https://play.google.com/store/apps/details?id=nl.skywave.ovi... ) which does have a nicer interface: You _can_ load a map and gawk at it, but by default it loads very fast and shows a list of stops/stations in order of how close they are, and clicking on them shows the up-to-the-minute (in some regions, up-to-the-second) exact departure times including any current delays.

In an public transport heavy region (lots of The Netherlands is PT heavy) this changes how you interact with public transport. You stop planning. You decide you want to go to X, so you walk to the nearest stop you know will take you to X (in contrast to someone who rarely uses PT or lives in a PT light area: They either don't know the routes and thus don't know which stop to walk to, or there is only one stop within walking distance if that), and as you walk, it takes all of about 5 seconds, literally, to know if you should walk briskly or have time for a detour or whatever. Or even check if a different stop would be more efficient.

It's powered by the same data. 'look, a map!' is visually the most interesting, and thus perhaps appropriate here, where I would assume most readers don't even live in Belgium.

Absolutely, the official apps are lacking. Google maps has incorrect timetables and the TEC app doesn't give you any way of knowing when the next bus will be and where in traffic it is. I recently had a bus at say 10:00, I get there at 9:58 and wait until 10:15 for the bus. Leaving the stop and seeing the bus pass a bit later is extremely infuriating. This kind of map lets you check where the bus actually is. Not so convenient on a phone but I'll take it.

Because there's about as many ways of taking public transit as there are users. For many, live maps are critical. I don't understand why either, but people want the "control" it offers and knowing that their bus is around the corner (it's not, the data is always over a minute stale because it goes through 5 intermediaries)

Delete that feature and you suddenly get a horde of angry users