The TFL system will remove a bus if it doesn't get an update often enough that includes actual progress on the route. This is in fact the opposite problem of what you mention, in that they don't do a very good job of predicting based on past performance. E.g. I used to take a specific bus to pick my son up from nursery that always would "disappear" for a certain number of minutes at a certain part of the journey because a very short stretch of the route was always extremely congested at that time of day.

It's a tricky one, because they have big concerns about over-promising (e.g. the bus could be stuck behind an accident instead, in which case guessing that it's 5 minutes away because of past behaviour will really annoy people) so in some situations they err on the side of caution.

But they are unable to get rid of all of the corner cases. E.g. a bus that moves rapidly for a short stretch, then gets "stuck", will often appear, disappear, appear, disappear, with much less progress in time estimates than elapsed time should indicate.

The thing is, the team working on it has a huge amount of gathered info on how to give these predictions in a way that tries to minimise surprise and avoid making promises that cause problems for people. E.g. often it's better to take a bus off the list so people who are in a hurry will grab a taxi, rather than "promise" the bus will be there in just another few minutes. They still get it wrong too often, but I really don't envy them trying to get the right balance between promising too much and too little.

> They actually do this as well (and many have live updating signs)

I don't know about London, I've seen some systems where the stops had "live-updating signs" but only provided the time of the next official passage. And while I wasn't clear, my bug is not just stop signage but phone access as well (that's most useful when e.g. it's raining cats and dogs and you want to avoid waiting in the rain at uncovered bus stops)

There's a standard by Google for transit timings, and Translink, the public transport authority in my state, outputs these times. They're live.

Apps like 'Transit' also (accurately) show the current GPS location of the bus as it approaches, and it updated every minute (I believe)

In London you can go to the TFL website and see live updating times for when the bus will get to your stop: https://tfl.gov.uk/travel-information/stations-stops-and-pie...

Oslo, Norway has realtime data available for all stops as well :)

http://reisapi.ruter.no/Help/Api/GET-StopVisit-GetDepartures...

>Returns a List of StopVisits (departures) from a Stop. If no time parameter is supplied, departures in realtime will be returned.

OK, that's really cool. Definitely means they have "a server, 3G/4G connectivity [and] GPS" though.

Not necessarily. I think some of the systems use radio links to a central location and transponders at fixed points on the route to track the buses.

There is an API for London: https://api.tfl.gov.uk/