PTV Group - Logistics Forum

Hi folks,

for demonstration purposes I calculated a dima with some special coinstraints:

• 5 locations somewhere on the German island Sylt
• A custom bounding rectangle which "excludes" the point in the far east
• Violations allowed

I wanted to demonstrate that the dima is complete (5x5 relations) and splits the relations into 3 categories:

• relation routed successful, without violations
• relation routed successful, with violations
• relation not routed successful, therefore estimated by direct distance

What surprises me: the point in the far east contributes with:

• 3 times without violations
• 2 times violated
• 3 times estimated by direct distance

How can this be? I expected the location to be "unreachable" from a symmetric perspective.
Bernd

OK, that was a tricky one - probably doesn't occur in reality

• The isolated coordinate in the east (green pin) is linked to the closest segment (green star) that touches the rectangle's border.
• That particular road is a oneway street which
  • enables the router to leave the place
  • but prevents him from reaching the eastern point

Thanks for the analysis, Frank!

That being said I recommend that you also check this article "xServer2: Handling of optimization on islands such as Sylt, Helgoland, ..." carefully if you are interested in "spatial" challenges

Bernd

In this context of "relation calculated or not" I just got some info from our DEVs:

If a location cannot be linked (because it is located in an isolated area): how is the distance / traveltime from the original isolated waypoint to the last possible road segment point determined?

• For off-road locations the speedForLinkDistance parameter is used to calculate the travel time based on the air-line distance to the linked road segment.
• For relations that cannot be calculated:
  • Distance is air-line distance multiplied with detourFactor(default 1.38)
  • Travel time is calculated based on that distance and averageSpeed (default 60)
  • The flag estimatedByDirectDistance is set to true
  • There are different reasons why a relation cannot be calculated:
    • Violations are disabled and there is no valid route without violation.
    • Certain restrictions cannot be violated at all.
    • There is no valid road segment within the maximum distance (maximumDistanceToSegment default 50 km).
    • There is no route at all between start and destination, e.g. start in Europe, destination in USA.
    • With routing type conventional the levelling heuristic can cause that certain routes cannot be found.
• For relations that can only be calculated with a route violation
  • The flag violated is set to true.