get_neighbor_rear_along_lane returns neighbor fore when neighbor rear is in a different road segment

[wulfebw]

When finding the rear neighbor using get_neighbor_rear_along_lane, the fore neighbor is selected rather than the rear in situations where the rear is in a different road segments. And more specifically, it primarily, and perhaps only, happens in the specific road segment considered in the attached notebook.

I think the bug is in the distance calculations, but I haven't figured it out yet. Included in the notebook is a copy of get_neighbor_rear_along_lane with a change that prevents the bug from occurring, but does so indirectly and so is not a great solution. The notebook also contains a minimal example demonstrating the bug.

get_neighbor_rear_along_lane.zip

[tawheeler]

I think the issue has to do with:

elseif is_between_segments_hi(veh.state.posF.roadind.ind, lane.curve) &&
       is_in_entrances(roadway[tag_target], veh.state.posF.roadind.tag)
    distance_between_lanes = abs(roadway[tag_target].curve[1].pos - roadway[veh.state.posF.roadind.tag].curve[end].pos)
    s_adjust = -(roadway[veh.state.posF.roadind.tag].curve[end].s + distance_between_lanes)

elseif is_between_segments_lo(veh.state.posF.roadind.ind) &&
          is_in_exits(roadway[tag_target], veh.state.posF.roadind.tag)
    distance_between_lanes = abs(roadway[tag_target].curve[end].pos - roadway[veh.state.posF.roadind.tag].curve[1].pos)
    s_adjust = roadway[tag_target].curve[end].s + distance_between_lanes

The s_adjust that is computed seems to mess up the calculation. Need to spend more time going over this.