Some GTFS-R Vehicle Positions Incorrect


I’m noticing that some of the coordinates returned by the GTFS-R vehicle position endpoint is a little strange.

I’ve been tracking a particular vehicle yesterday:

Vehicle ID: 4337.4338.4339.4340.4341.4342.4343.4344
Trip ID: 152T.435.123.60-20160801.A.8.42505972
Route ID: WL_1b

In sequential order, the GTFS-R feed returned the vehicle position to be:

Granville.Pendle Hill 3 Loc @ 1470063822
Granville.S18.1 Loc @ 1470063915
Granville.Toongabbie 3 Loc @ 1470063955

However, the coordinates returned for Granville.S18.1 Loc deviated significantly from the expected route:

Would this be because Granville.S18.1 Loc was incorrectly returned by the feed? or perhaps the coordinates for Granville.S18.1 Loc are placed on the wrong part of the track


Pink is the route as per shapes.txt, blue is the route as plotted by the data returned by the GTFS-R feed. Star points are the individual nodes being plotted by the data returned by the GTFS-R feed.


Someone from our brains trust has advised that this is a known issue in the Sydney Trains’ system due to S18.1 being a train location name on two rail control systems.


Ah, I see. I suspect that’s a similar issue with Granville.S17.3 Loc?


could be…

there are 3 train locations that do it. it isn’t consistent and the impact is only brief - the train will jump off route then back on route 10-20 seconds later


Thanks @yvonne.lee :slight_smile:

I think I’ve got a work around for the interim!


it’s also been raised with Sydney Trains to fix (apparently been fixed in the past… but something happened)