Set the default u-turn time to zero

CHANGELOG.md

@@ -1,5 +1,6 @@
 ### 10.0 [not yet released]
 
+- the default u-turn time is now 0, the default u-turn weight is still infinite 
 - turn restriction support for restrictions with overlapping and/or multiple via-edges/ways, #3030
 - constructor of BaseGraph.Builder uses byte instead of integer count.
 - KeyValue is now KValue as it holds the value only. Note, the two parameter constructor uses one value for the forward and one for the backward direction (and no longer "key, value")

core/src/main/java/com/graphhopper/routing/weighting/DefaultTurnCostProvider.java

@@ -75,7 +75,12 @@ public double calcTurnWeight(int edgeFrom, int nodeVia, int edgeTo) {
 
     @Override
     public long calcTurnMillis(int inEdge, int viaNode, int outEdge) {
-        return (long) (1000 * calcTurnWeight(inEdge, viaNode, outEdge));
+        // Making a proper assumption about the turn time is very hard. Assuming zero is the
+        // simplest way to deal with this. This also means the u-turn time is zero. Provided that
+        // the u-turn weight is large enough, u-turns only occur in special situations like curbsides
+        // pointing to the end of dead-end streets where it is unclear if a finite u-turn time would
+        // be a good choice.
+        return 0;
     }
 
     @Override

core/src/test/java/com/graphhopper/routing/weighting/custom/CustomWeightingTest.java

@@ -409,7 +409,8 @@ public void calcWeightAndTime_withTurnCosts() {
         EdgeIteratorState edge = graph.edge(1, 2).set(avSpeedEnc, 60, 60).setDistance(100);
         setTurnRestriction(graph, 0, 1, 2);
         assertTrue(Double.isInfinite(GHUtility.calcWeightWithTurnWeight(weighting, edge, false, 0)));
-        assertEquals(Long.MAX_VALUE, GHUtility.calcMillisWithTurnMillis(weighting, edge, false, 0));
+        // the time only reflects the time for the edge, the turn time is 0
+        assertEquals(6000, GHUtility.calcMillisWithTurnMillis(weighting, edge, false, 0));
     }
 
     @Test
@@ -419,7 +420,7 @@ public void calcWeightAndTime_uTurnCosts() {
         Weighting weighting = CustomModelParser.createWeighting(encodingManager, new DefaultTurnCostProvider(turnRestrictionEnc, graph.getTurnCostStorage(), 40), customModel);
         EdgeIteratorState edge = graph.edge(0, 1).set(avSpeedEnc, 60, 60).setDistance(100);
         assertEquals(6 + 40, GHUtility.calcWeightWithTurnWeight(weighting, edge, false, 0), 1.e-6);
-        assertEquals((6 + 40) * 1000, GHUtility.calcMillisWithTurnMillis(weighting, edge, false, 0), 1.e-6);
+        assertEquals(6 * 1000, GHUtility.calcMillisWithTurnMillis(weighting, edge, false, 0), 1.e-6);
     }
 
     @Test