slip roads
  • Vote Up0Vote Down nathaniel1222nathaniel1222
    Hello, I'm in the Washington D.C. area using MapFactor Navigator, v.1.0.62 on the new Nexus 7 (Android OS). The Navigator is working brilliantly except for one issue: on a stretch of interstate that has parallel 'local lanes,' Navigator tells me to exit onto the parallel local lane (i.e. slip road) at every exit and then says to get back on the main interestate at every exit. If I followed Navigator's instructions, I would be exiting and entering the interstate at every exit instead of staying on the interstate until I reached the exit I truly need. Any suggestions, or is this a software programming issue?
    Thank you.
  • 14 Comments sorted by
  • Vote Up0Vote Down tomastomas
    this is due to incorrect speed attributes in free maps - you can try to increase preference for motorways (interstate) in settings/vehile profiles/car/road restrictions
  • Vote Up0Vote Down johnjorejohnjore

    I too was wondering why I was directed off/on the Australian highways. (PC Navigator Free 12.3/4)

    Is there a way (or an existing web site?) to generate a report of slip roads with same speed as the motorway to try and fix these? (Maybe broken down into country, state or county?)

     

    JJ

  • Vote Up0Vote Down tomastomas
    to edit map create account at www.osm.org and start contributing, it is quite easy
  • Vote Up0Vote Down OldieOldie
    I think, this is something for the programmers of Mapfactor. Other programs do not use slip roads, even if they use OSM maps too.
  • Vote Up0Vote Down tomastomas
    yes, there is a way around it, mdx will work on it, but better way is to have correct map data
  • Vote Up0Vote Down johnjorejohnjore

    Tomas, i think you missed my point.


    While its easy to edit osm data, finding each and all of the data/entries that causes this issue in Mapfactor is not so easy.


    JJ

  • Vote Up0Vote Down OldieOldie
    And existing OSM data are not wrong! Slip roads in most cases do not have a designated speed limit. What speed limit should I set in theses cases? If I invent any speed limit, I make OSM data incorrect, which formerly were correct ...
  • Vote Up0Vote Down tomastomas
    Hi Oldie, that would actually mean that it is faster to go through slip road :-)
  • Vote Up0Vote Down OldieOldie
    Oh no!  See this: http://forum.mapfactor.com/discussion/406#Item_2 If you use the slip roads there, you leave the Bundesstraße (national road), have to give way at the crossing if not to stop at the crossing, accelerate again and have to give way again, when entering the Bundesstraße. Only the fast and furious are faster on slips roads there ...
  • Vote Up0Vote Down mdxmdx
    I agree with Oldie - do not add speed limits which do not exist in reality ... see http://wiki.openstreetmap.org/wiki/Verifiability
  • Vote Up0Vote Down jacobjacob
    Yes but this is the fundamental problem - the speed limit does not represent the speed you can realistically travel along that road. Unfortunately, when making a navigation app it is not easy to distinguish which road is faster purely from speed limit values without looking at each case individually.

    And in any case  slip road DO have a speed limit - in the UK the maximum speed is 70mph on ANY road.
  • Vote Up0Vote Down jacobjacob
    But I DO agree that it is better not to solve it by artificially changing a speed limit of slip roads.
  • Vote Up0Vote Down johnjorejohnjore

    I have no experience with navigation software, but I would have thought routing through intersections would incure "a penalty", compared to a road section without intersections? (Especially if speed limits in both options are identical?)


    I thought Australia also had speed limit signs on (some) slip roads, so not convinced it would be wrong to add the correct speed limits to these slip roads, but this may be the minority of use cases where this issue occours.


    anyway, if mapfactor belives the fix is to modify its routing engine, how high on mapfactors list of priorities is this issue as its beyond annoying to be routed off/on the motorway.


    JJ

  • Vote Up0Vote Down pocopoco

    This is a problem in Virginia as well, however, many of our freeway exit ramps do indeed have sped limits imposed on them that are smaller than the freeway speed.  I will check to see if this is the case on the road that demonstrates the issue on my way home today.


    Feature request: Periodically have the system tell you something interesting about where you are driving to keep you awake...

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