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chairemobilite / trRouting

Transit Routing server app using Connection Scan Algorithm and flexible parameters
GNU General Public License v3.0
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Strange itineraries when routing based on arrival time #298

Open tibobliss opened 3 months ago

tibobliss commented 3 months ago

Routing using the Arrival time parameter seems to introduce distorsions in the trip itinerary chosen by trRouting. For instance:

Here is a random trip using a random starting time (7:11). Notice how the proposed itinerary below includes a 3-minute walk from the last stop for a total trip time of 41 minutes and an arrival at 7:52. image

If we switch to using the arrival time and set it to 7:53 (to account for any rounding), we get the itinerary below. Notice how the last stop changes to the next one on the route, but we still get a 3-minute egress walk and a total trip time of 41 minutes, arriving at 7:52. image

Now, if we set the arrival time to 8:00, we get the strange behavior illustrated below. The starting time is the same as the 2 other scenarios, but the arrival time is 4 minutes later at 7:56, for at total trip time of 46 minutes. Notice how the egress stop is farther down the route and the itinerary then backtracks on foot via a 7-minute walk. image

It seems like trRouting tries to arrive as close as possible to the Arrival time parameter, even if that introduces extra vehicle time and walking time.

greenscientist commented 3 months ago

Moved this issue to TrRouting, since the problem is at that level