Iterations may end up with many pure transit_walk trips.
By a "pure" trip I mean one that only consists of one leg, with this mode.
The pure transit_walk trips can be traced back to the transit router (TransitRouterImpl), which contains the following lines
So it returns a direct transit_walk if this is better than including a real transit leg.
This functionality was introduced to avoid non-sensical transit trips. They happen for example:
in areas without pt. The pt router then constructs a long walk to a pt stop, inserts a short pt leg, followed by another long walk to the final destination.
during times withouth pt. The pt router than constructs a walk to a pt stop where the agent waits a very long time for the pt vehicle.
The problem now seems to be that from the perspective of the transport planner, these pure transit_walk trips should just be normal walk trips. We are, however, a bit sceptic to just switch the mode (this would be easy, see the createDirectWalkList(...) method in TransitRouterImpl), since this would imply walk trips could be constructed without necessarily having them in the ChangeXxxMode specification. That is, a mode which looks the same from the perspective of the transport planner may look different from the perspective of the software.