--- a/artifacts/src/main/java/org/dive4elements/river/artifacts/model/WQKms.java	Fri Oct 17 12:50:35 2014 +0200
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/model/WQKms.java	Fri Oct 17 13:17:12 2014 +0200
@@ -162,6 +162,21 @@
         return new double[] {getKm(0), getKm(size()-1)};
     }
 
+    private static final double EPS = 1e-5;
+
+    public Double sameKm() {
+        int s = size();
+        if (s < 1) return null;
+        if (s == 1) return getKm(0);
+        double a = getKm(0);
+        double b = getKm(s-1);
+        double c = getKm(s/2);
+
+        return Math.abs(a-b) > EPS || Math.abs(a-c) > EPS || Math.abs(b-c) > EPS
+            ? null
+            : a;
+    }
+
     @Override
     public boolean guessRTLData() {
         return DataUtil.guessSameDirectionData(ws, allKms());