Had a bit of time on my hands, with the builders in. So I had a look at the 222 earlier today through using the London Vehicle Finder site at https://lvf.io/. This is a useful tool, as not only does it show you the next stop for every bus on the route but also shows the bus fleet and registration number. It also does not (or should not) “lose” vehicles during the day as it shows the most recent report generated by a bus until it finishes for the day - and even then it lists the vehicle as
having operated on the route.
I used LVF to capture data for the route at roughly three minute intervals for over an hour. I have put the results on an Excel file at http://mjcarchive.www.idnet.com/route222.xlsx; follow the colours to see where the buses were due next on each call. Unless the time due is more than a minute or two ahead (or impossible) I have not shown the time.
Four buses show particularly odd behaviour:
LK16DGO is initially shown as due to arrive at the first stop in Uxbridge at 1106. But at 1059 it materialises a being due next at Porters Way (a long way along he route) at 1128. I have no idea whether this (presumably bogus) expectation would appear on the Countdown screen. Then, at 1115, it is shown as due to arrive at the first Uxbridge stop at 1112!
LK16DFD is initially shown as due to arrive at the first stop in Uxbridge at 1126 but at 1129 it is shown due to arrive at Yiewsley Library at 1139. I did not continue long enough to see whether it reverted to Uxbridge at some stage.
LK67CXN is shown as due to arrive at the first stop in Uxbridge at 1145 but London Vehicle Finder shows it as not having operated on the route after 1150. I presume that it kept on reporting something (maybe not Uxbridge at 1145 throughout) until 1150 then disappeared form the feed.
LK16DGO is shown as due to arrive at the first stop in Uxbridge at 1047 … up to and including the 1114 report (I would not expect Countdown screens to edit out negative waiting times!), after which it shows up as expected at 1116
Of these four vehicles, the first three were the only ones (for which I observed claimed departure times) which I can be confident registered an expected arrival time at Belmont Road on the way in. Most buses registered their last expected arrival time at Crown Walk (the preceding stop). These appear to have then reported correctly for the outgoing journey.
Two vehicles - LK16DFL and LK16DFZ - set off southbound without having arrived from the south first (at least within the period viewed). These first cropped up in the LVF results after the first stop and if they appeared in the feed for the first stop it can only have been for the briefest period.
Also noted that LK67CXJ’s expected arrival time at the first Uxbridge stop changed at 1059 from 1116 to 1106. In effect it took the slot previously shown by LK16DGO above. LK16DGO then takes over the 1116 slot (as set out above)
As the terminus is effectively the depot, it is presumably comparatively easy to shuffle the vehicle pack around and put out another vehicle if (say) the arriving vehicle is late or has a mechanical or cleanliness problem. I can sort of see how confusion could arise in these circumstances; a bus has arrived so its path southbound can be projected but that path is actually used by another vehicle.
The other document worth a look is the working timetable at
https://s3-eu-west-1.amazonaws.com/bus.data.tfl.gov.uk/schedules/Schedule_222-MF.pdf. This shows two distinct stands in use for the route UX GR S (the garage) and UXBRSNHS (Bakers Road, Stop H stand). UX GR S actually occurs twice for some reason. Buses arriving at Stop M (the first pick up) can do so from either of these stands or straight from the depot (UX). The working timetable cannot be lined up with LVF as there is no identifier in common (plus, if there is disruption buses could work quite differently) but if the last reported call on arrival is relevant, that could be associated with the stand/source of the southbound bus.
A couple of unrelated points also stood out from the data. No expected arrival times at all were reported for stops between Hounslow West and The Bell in either direction. Instead we get times several minutes ahead at one or the other, depending on direction. Also there appears to have been an extended period during which buses from Uxbridge were expected at the Treaty Centre but presumably got turned short at The Bell (there is one identified short journey in the data). Perhaps there were local problems causing curtailment but I don;t think that can explain the missing tranche of stops; unexpected diversions do not usually “report” that way.