Proposal:Add a systhematic location to put the merging node when merging exit ramps on motorways or other highways

Add a systhematic way to choose the location of the merging node when merging exit ramps on motorways or merging highway links to main roads.
Proposal status:	Draft (under way)
Proposed by:	Kaligrafy
Applies to:	way, node
Definition:	Where to put the merging nodes?
Draft started:	2022-05-03

Proposal

In the wiki, it says that the merging lanes should be connected to the main road as soon as the physical separation ends, but there is no indication of which angle to use or which distance to use on the merging segment to the connecting node. We propose to place the merging node at the end of the merging dashed line if present, or otherwise, place the merging node to follow the typical/mandatory movement of vehicles in the road as close as possible. The rationale here is to reduce artificial angles that vehicles do not follow and make sure that if a routing engine is penalizing angles and turning radii, that the penatly will not be artificially increased (an increased number of routing engine starts to include turning radius and angle penalties, OSRM includes such parameters already).

Rationale

There should be a systematic location for the merging node, otherwise in some case, the angle could be too small or too wide and would not follow the real movement of vehicles on the road. In the Montreal area (Quebec, Canada), we started some years ago to map the ramp merging nodes at the end of the dashed lines instead of right after the physical separation, but this triggered some discussions lately.

Examples

Where to put the merging node

Where to put the merging node?

Where to put the merging node?

Here are three examples: where would we put the merging nodes for the three connections illustrated int the 3 images (the last image contains 2 merging locations)?

Comments

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