Don't snap to private grounds on bike profile

[chaupow]

Issue

On the bike profile, we allow routing through private grounds such as parking lots or pushing the bike on foot paths.

For routing this is usually not too much of an issue because speed/weight values should ensure that we prefer routes on "normal roads" compared to parking lots etc. and routing through these is only used if necessary.

However, when the destination or start of a route are close to foot paths or parking lots, we snap on the closest routable segment. So if a start is closer to a parking lot than to a road we snap to the parking lot even though it would make more sense to start on the nearby road.

Snapping in OSRM only takes in account big or small graph components when choosing where to snap to and prefers snapping to big components.

Examples

Goal

For bikes, it would be additionally desirable to prefer snapping to the closest road and not to foot paths or parking lots.

[chaupow]

Approach

• [ ] in profiles, add the option of adding avoid_as_startpoint (aligned with is_startpoint)
• [ ] flag parking lots and foot paths to avoid_as_startpoint = true
• [ ] change the snapping behaviour as follows
  • let the rtree find nearest, nearest of big_component and nearest that is not avoided as startpoint
• [ ] tbd what to do then

[emiltin]

in the example above, it makes sense. but if you actually start on a parking lot, i think you want the route to start where you are, not at a nearby road?

[chaupow]

That's right. Ideas floating around are:

• run two queries from a point that is the nearest and one that was avoided and somehow pick one
• compare the distance of given coordinate with the nearest edge and the nearest on the road and pick based on the distance

Not very sure how to solve this yet either.

[github-actions[bot]]

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