Odd bug? with VTA light rail 902

[Robert]

I think I can reproduce this pretty reliably.

If you're at a light rail station and want to take the 'next train',
the My Transit Trip schedule (that you confirm) will tend to show the
right 'next train'. E.g., if I'm at Old Ironsides and I want to go to
Champion, and it's 7:30 AM, it will say that the next train on the
schedule is at 7:42-7:47. However...once I've confirmed that and go
into the 'I'm waiting for the train' screen, it seems to skip that
7:42 train, and thinks I'll be waiting until 7:57 for the train
_after_ that, so it says that I have 27 minutes to wait. Obviously
this is not correct. You might want to check out the real time code
for the light rail. It looks like the schedule's in there right, but
the 'next train' calculation might be messed up.

[Liping Zhang]

Hello Robert:

Thank you so much for participating in our project and being interested
in the PATH2Go application,
We gratefully appreciate your feedback,

I will try to reply to your posts one-by-one:
For this issue, we will look into the data and see what happened ( I
assume that you are referring to the 902 train line station Old
Ironsides, right?),
There is a logic that calculates the walking time needed from the user
the current location to the boarding stop, and will skip the current
train if it determines that the next train arrives in a couple minutes
and the user won't make it,

However from your description, seems that it is not the case since the
next train was 7:42 am (you had 12 minutes, in which case it should show
the next train as planned), there might be a bug in our program,

again, thank you very much for reporting this issue,

Thanks

Liping Zhang,
Assistant research engineer,
California PATH,
University of California, Berkeley,
lpz...@path.berkeley.edu

[Robert]

I'll try sitting a block from Old Ironsides and just keep missing the
train, and see what it keeps telling me the 'next train' is to
Champion. Perhaps this will help you nail down what's going on. I'll
report back in a few hours.

[Liping Zhang]

Robert: Thank you so much for the efforts of helping us to troubleshoot the issue, really appreciated,
Liping.

[Robert]

I actually just got it. Okay, here's what I did:

I'm about .3 miles from Old Ironside now. Time is 2:24. I say I want
to do a new transit trip to Champion. On the 'submit' screen, it
realizes that the next train is at 2:42-2:49 -- which is correct
according to the VTA schedule. Now I submit, and I'm on the 'Real time
Trip Segments' screen - and it now tells me 'Board at OLD IRONSIDES:
Next Train: 3:12 PM. Bingo! It just completely skipped the 2:42 train
even though I have 15 minutes to get there, and is showing me the
train -after-.

Hope this helps!

On Sep 22, 2:21 pm, Liping Zhang <lpzh...@path.berkeley.edu> wrote:
> Robert: Thank you so much for the efforts of helping us to troubleshoot the
> issue, really appreciated,
> Liping.
>

[Liping Zhang]

Robert: This is really really helpful,
I spent the last hour looking for the problem (apparently there is a
bug), and I found it,
here is the problem: (you may or may not be interested in what happened,)
it occurs when, in the next 7 trips for a route, if there is one trip
that the bus/train passes by a same stop twice, and when that stop
happens to be the last stop of the trip, the arrival time for that trip
will somehow override the upcoming trip, or the "next train" ,
and cause the problem you saw.

recompiling the code now, and should have resolved the problem,
For VTA 902, the same won't happen again today, we can see if this will
persist tomorrow (hopefully won't),

Liping.