TrackerNet is an fixed-line diagram/information service, implemented between 2007 and 2009(?) that shows signals, points, and a history of all train movements derived from the ATP sensors.
The originally SVG system UI is implemented as a C# WPF (XAML) application. The related Train Lists application provides predictions of arrival times, which the publicly available data is derived from.
Unfortunately, despite having up to 23,000 internal clients, performance was not considered a priority.
The API service runs on IIS 7 ASP.NET 4.0.30319, with customErrors mode="off".
In June, a required feed for some of the data was being turned off every night at between 01:45 AM and 6 AM, but this was fixed after a couple of days.
There currently appear to be three or four servers mirroring the feed - this can be seen by the timestamps returned in the XML. This suggests is may be possible to track at higher resolution than 30 seconds.
Documentation is at http://www.tfl.gov.uk/assets/downloads/businessandpartners/Trackernet_Data_Services_Guide_Beta_0_2.pdf. The original service's documentation was taken from http://data.london.gov.uk/documents/apibeta-trackernet-services-guide.pdf.
The API URL in the documentation is not accurate: it is actually http://cloud.tfl.gov.uk/TrackerNet/. The URLs are all case-insensitive.
There are currently four documented data services available from London Underground that will return cached information about train predictions and network status. There were also three more services that were undocumented, and now unknown. Usage of these is undefined and in certainly unsupported by TFL.
|4||Train predictions (summary)||Yes||Yes|
|5||Train predictions (detailed)||Yes||Yes|
select LCID, LN, TrackCode, SetNo, Location, Destination from tfl.trains.detail
where line in ('B', 'C', 'D', 'H', 'J', 'M', 'N', 'P', 'V', 'W') and maxtime=1000 | unique(field="LCID")