OpenStreetMap
This routes from Batangas City to Tunasan, Muntinlupa (Mapzen/OSRM] looks strange. Rather than taking Susana Heights/MCX Exit, Susana Heights Road, and National Road (Daang Maharlika), navigations directions tell you to exit at Carmona Exit and take Governor;s Drive, General Malvar Street and then turn left to National Highway (Daang Maharlika) northbound. My knowledge tells that the main route to Tunasan is via Susana Heights Exit. OSM routers still wants you to take Carmona Exit to Muntinlupa or San Pedro, and it looks like a routing issue.
Why is that happening? Can someone tell me reasons for that routing situation and possible road data fix-up?
Discussion
Comment from Hjart on 8 June 2016 at 10:39
This probably has to do with road classification: The Carmona exit route is trunk all the way with no speed limit given (in the OSM data), while Susana Heights is primary only as well as limited to 60 km.
Comment from Piskvor on 8 June 2016 at 11:40
Looking at http://map.project-osrm.org/debug/#15.08/14.3805/121.0447 and http://map.project-osrm.org/debug/#15.08/14.3283/121.0669 , the router seems to be very optimistic about General Malvar Street and the National Highway , but not entirely happy about Susana Heights Rd. Perhaps lane+maxspeed tagging?
Comment from BushmanK on 9 June 2016 at 01:46
https://www.openstreetmap.org/directions?engine=osrm_car&route=14.38003%2C121.04107%3B14.38559%2C121.04256#map=17/14.38161/121.04364 - obviously, it doesn’t want to use right turn from Exit 29 ramp to Susana Heights Road. Check if there is common node and/or wrong restrictions for this right turn.
Comment from BushmanK on 9 June 2016 at 01:49
I mean, Exit 26 ramp.
Comment from TagaSanPedroAko on 9 June 2016 at 05:16
This issue is likely to do with speed limits. Susana Heights Road has complete lane count but no speed limit. Governor’s Drive and General Malvar Street has complete lane count, but they also need an approximate speed limit.
I found an issue that likely caused that “strange”routing, and it is a one-way segment that has not been changed to two-way. That is likely causing routers to take Alabang Exit instead of Susana Heights/MCX Exit. I fixed it in JOSM, along with addition of approximate speed limits in Governor’s Drive and General Malvar Street (from Carmona-Binan boundary to National Highway only). I’ll make some follow-up fixing on National Highway north of Binan, which include addition of approximate speed limit (there are no traffic signs to look up at that highway).
Thanks for feedback to my issue.
Comment from TagaSanPedroAko on 9 June 2016 at 05:17
See this changeset.