diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -428,13 +428,15 @@
 			if (!IsCompatibleRail(GetRailType(tile), railtype)) return_cmd_error(STR_ERROR_IMPOSSIBLE_TRACK_COMBINATION);
 
 			ret = CheckTrackCombination(tile, trackbit, flags);
-			if (ret.Succeeded()) ret = EnsureNoTrainOnTrack(tile, track);
 			if (ret.Failed()) return ret;
 
 			ret = CheckRailSlope(tileh, trackbit, GetTrackBits(tile), tile);
 			if (ret.Failed()) return ret;
 			cost.AddCost(ret);
 
+			ret = EnsureNoTrainOnTrack(tile, track);
+			if (ret.Failed()) return ret;
+
 			/* If the rail types don't match, try to convert only if engines of
 			 * the new rail type are not powered on the present rail type and engines of
 			 * the present rail type are powered on the new rail type. */