openplans/OpenTripPlanner — Issue #570: Soft-limited nonlinear walk/board cost curves
Author: andrewbyrd
Created: 2011-12-05 18:54:13+00:00
State: open

In the case where no path exists that respects the walk limit, the plain A* router retries until it finds a path, but the MOA* router does not. The idea was to literally interpret hard limits and use soft limits for anything else.

Switch over to soft limits and see if they give good results with MOA*.
This should solve the failed MOA* searches mentioned in the comments of #352.
This will necessitate a flag in the response to indicate trips with excess walking.

There have been problems in the past with quadratic walk cost curves causing overflow, so I will try introducing a big step at the walk limit, then scale the marginal walk cost up beyond that point.

David T and I discussed another problem where the N "best" trips all had 2 transfers, and did not include an obviously interesting alternative with only one transfer. Soft-limited board costs, with every boarding after the first increasing in cost, may be a solution.