Really broke light rail arrival unintentionally
Robert
on 'My Transit Trip'. I didn't intend this to happen, but...
1. Created a trip from Old Ironsides to Champion Station. (The train
arrival time was correct for the record, I'll see how it is tomorrow
when I'm on transit).
2. Drove past the Old Ironsides stop in my car, at the approximate
arrival time - and at about the same time that a 902 was going
northbound in the OPPOSITE DIRECTION. (The road I was on followed the
light rail for about 3/4 of a mile).
3. Approximately paced the northbound light rail with my car, until it
passed me and went a different direction than me.
What PATH2Go did:
1. Assumed that I had correctly got on the southbound light rail
train. Status went from 'Train arrived' to starting to count down
minutes to Champion station, despite the fact that I was going the
wrong way.
2. Counted down minutes from about 6 to 1, that I would arrive at
Champion. Again, for about that entire period of time, I was actually
travelling in the opposite direction. My travel could have been
interpreted either as being in a car, or being on the right light rail
in the wrong direction. It never recalculated for this.
3. Got to the state of 'Arriving', and then spins in that state
indefinitely. I never got the 'You are approaching your train station
message', presumably because the GPS never detected me getting near
Champion station - which of course I didn't!
4. Followed my car all the way home on GPS, despite the fact that I
was nowhere near the light rail track by then. The state was still
'arriving' until I finally 'cancelled the trip'.
Potential issues uncovered:
1. Application doesn't check the direction of travel out of a station
once you start moving at the 'right time'. That could mean getting on
the wrong train/bus, or in the wrong direction.
2. Application doesn't check for rational route (in other words, that
you're on a light rail, versus bus, versus in a car) and have a 'give
up' when it detects one of these conditions.
3. Doesn't recalculate or give up if it realizes you're going the
wrong way or on the wrong route. Whether this means figuring out what
transit you ARE on, or simply saying 'Error, wrong transit route', or
whatever...it doesn't seem to do it.
* As an aside based on the above, I'm curious, if I'm at a bus stop
with multiple lines, how the app would act if I accidentally got on
the wrong bus. Should it detect that based on the route I take, or
departure time?
Liping Zhang
Again ,thank you very much for the suggestion.
Actually the issue you brought up has been a major design issue during
our implementation of PATH2Go.
We had a more strict rule of matching of the user's GPS trajectory to
their itinerary progress in previous version of PATH2Go, and it worked
ok for most cases,
but was not always reliable when a bus route contains circles, u-turns
(we don't have the detailed route shape data for all routes), etc, or in
downtown SF when GPS reception could be really bad, and false alarms
were given.
So we went to another direction that we relaxed the matching rules, and
rely mostly on the detection of user's GPS at the boarding stop.
Whenever that is detected, PATH2Go assumes that the user will catch the
bus / train. User might be able to tell from the map whether he/she is
on the right route, with the blue dot indicating current location and a
green/blue polyline showing the route.
This way, we lost the capability of warning user when he/she is on the
wrong bus /train. (We hope what with PATH2Go showing the bus route id
and direction on the real-time trip segment box, the chance of taking
the wrong bus could be reduced), while also avoided the false alarms for
the users actually taking the right bus / train. Latter one we think
might be critical to PATH2Go.
So if at a bus stop with multiple route, and the user accidentally takes
a wrong bus, PATH2Go would assume that the user is on a bus from the
planned route, not the actual bus.
Thanks,
Liping.
Robert
in case it hadn't been looked at yet. Now that I know that it has,
I'll just run with it!
Thanks!
On Sep 23, 10:01 am, Liping Zhang <lpzh...@path.berkeley.edu> wrote:
> Hello Robert:
>
> Again ,thank you very much for the suggestion.
>
> Actually the issue you brought up has been a major design issue during
> our implementation of PATH2Go.
>
> We had a more strict rule of matching of the user's GPS trajectory to
> their itinerary progress in previous version of PATH2Go, and it worked