Announce instructions on ways with lanes that force turns #4662
Description
At intersections like this one ^ if a route does not involve making a left onto Bryant, we should issue a continue straight instruction, otherwise it is easy to fall into the trap of being forced into a left turn.
Lane parsing is succeeding here, the response at the above intersection ^
JSON response with lanes indications
``` { "intersections": [ { "bearings": [ 45, 90, 135, 225, 315 ], "location": [ -122.409767, 37.770337 ], "entry": [ true, true, true, false, false ], "classes": [ "motorway" ], "lanes": [ { "valid": false, "indications": [ "left" ] }, { "valid": true, "indications": [ "left", "slight left" ] }, { "valid": true, "indications": [ "slight left" ] }, { "valid": true, "indications": [ "straight", "slight left" ] }, { "valid": false, "indications": [ "straight" ] } ], "in": 4, "out": 1 } ], "geometry": "s_peF`dcjVBk@Hy@F[H]J]BE", "maneuver": { "bearing_after": 95, "location": [ -122.409767, 37.770337 ], "type": "on ramp", "bearing_before": 135, "modifier": "slight left", "instruction": "Take the ramp on the left towards US 101 South: San Jose" }, "duration": 7.2, "distance": 91.2, "destinations": "US 101 South: San Jose", "name": "", "weight": 7.2, "mode": "driving" }, ```The suspicion is that the continue straight instruction is being suppressed because the continue straight turn is considered obvious.
To do
- Develop recognition in OSRM for situations like these: at an intersection, if the approach way has lane tagging on it and any of the lanes force maneuvers (i.e. you must turn left at the left two lanes) (and the number of forced maneuvers make a continue maneuver ambiguous), do not suppress a step there, or do not consider any turn obvious.