Understanding some "Road restriction" parameters
  • Hi !
    I'm a French user of MapFactor Navigator for Androïd. Great application ! Congratulations !

    Theres a discussion with the same title in the category "Feature requests" but I think it is better here ;-)

    So I
    ask myself the same questions : I don't really understand how "use
    speed restriction" acts on calculating the route and how this parameter
    combines with "Preference" percentage ?

    Is there a documentation that describes those parameters ?

    Could someone bring us some explanations ?


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  • Hi!

    I also would like to know if "speed restrictions" are connected with roads /Countries, and they are the highest speed limit/, or with my car /my own preferences, my average speed on this type of road/???

    The second parameter "preference" - I set it experimentally. It is connected with speed restrictions and important for routing. IMHO it would be great, if the best routing would be, with all preferences set to 50. But it is not. Everybody know, that the bypas of the town is /should be/ fastest than road through the center, so if it is not, You have to increase preferences of this bypas. But increasing it too much, cause other problems, and routing is too far from shortest/fastest.

  • If you have any recommendations how to recognize that given street is in the city/village in OpenStreetMap let me know. This flag is not filled in for OSM source (only TomTom and other providers) so for you it is impossible to "tweak it" with preferences.

    Preferences are used for speed/fastest routing only (I should check it, but I am almost sure). Increasing preferences you increase speed, but the result times are computed from original speed.
  • Lets think about it...
    It is obvious, that the bypas of the town is better - longer, but faster and more comfortable (and economic - less fuel spend for it). This roads have less cross roads, traffic lightings, pedestrian crossings, less cars driving in the others (left/right) directions, and so on. This roads are "bigger" and in better conditions, and have higher average actual speed.
    We also know that there are much more traffic lights and pedestrian crossings than it is set in OSM, especially in the towns.
    I don't know the algorithm of routing, but adding this informations (for example each traffic lighting, adds 30 seconds to route, each cross road one second) shoud give us better result.

    But now we can experiment with it, for example:
    1/ set speed restrictions for all kind of roads, the highest limit for Your Country is IMHO better than my own average speed.
    2/ set all preferences to 50 (percent i think).
    3/ set routing mode to fastest
    4/ set start route at the "beginning" of Your town (for example 51°04'57.7"N
    5/ ...finish route point at "the end" of this town (51°07'46.5"N

    Routing goes through the center of Wroclaw.

    Now by increasing preferences, as less as possible, we can change the routing :

    Preferences: from 50/50/50/50/50/50/50/50/0
    to:80/80/80/80/50/50/50/50/0 it is o.k., but too much.
    to:59/59/59/59/50/50/50/50/0 it is o.k. - on my map routing goes around the center.

    So for me this parameters are better.

    The same, but as less as possible (from 50 to 20) for small roads.

    And maybe it is good time to think about connection GPS with ECU (engin control unit)?

  • Hello,
    there is a term "<limit_expansion>" in the settings.xml changing the value will increase the computing steps on mobile PNAs and so should make a better routing. I didn't try it yet so I don't know if it really works. In the end I anyway doubt it, that there ever will be a navigation-SW that always will find the "best" way without having acess to real-time traffic information, when the route let's say is longer then between 500 - 1000 km. The calculated route will,  I presume, always be a compromise.

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