(svn r12390) -Fix [FS#1851]: trams failing to turn on bridge heads/tunnel entrances.

src/road_func.h

@@ -114,6 +114,20 @@ static inline RoadBits DiagDirToRoadBits(DiagDirection d)
 	return (RoadBits)(ROAD_NW << (3 ^ d));
 }
 
+/**
+ * Create the road-part which belongs to the given Axis
+ *
+ * This function returns a RoadBits value which belongs to
+ * the given Axis.
+ *
+ * @param a The Axis
+ * @return The result RoadBits which the selected road-part set
+ */
+static inline RoadBits AxisToRoadBits(Axis a)
+{
+	return a == AXIS_X ? ROAD_X : ROAD_Y;
+}
+
 /**
  * Finds out, whether given player has all given RoadTypes available
  * @param PlayerID ID of player