diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index dd6e6c7da8..86e0fbbc71 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -1466,7 +1466,7 @@ CommandCost CmdConvertRail(TileIndex tile, DoCommandFlag flags, uint32 p1, uint3
 
 					/* When not coverting rail <-> el. rail, any vehicle cannot be in tunnel/bridge */
 					if (!IsCompatibleRail(GetRailType(tile), totype) &&
-							HasVehicleOnTunnelBridge(tile, endtile)) continue;
+							TunnelBridgeIsFree(tile, endtile).Failed()) continue;
 
 					if (flags & DC_EXEC) {
 						Track track = DiagDirToDiagTrack(GetTunnelBridgeDirection(tile));
diff --git a/src/road_cmd.cpp b/src/road_cmd.cpp
index 9e9f9c1416..7ee64c795d 100644
--- a/src/road_cmd.cpp
+++ b/src/road_cmd.cpp
@@ -192,10 +192,12 @@ static CommandCost RemoveRoad(TileIndex tile, DoCommandFlag flags, RoadBits piec
 			if (!EnsureNoVehicleOnGround(tile)) return CMD_ERROR;
 			break;
 
-		case MP_TUNNELBRIDGE:
+		case MP_TUNNELBRIDGE: {
 			if (GetTunnelBridgeTransportType(tile) != TRANSPORT_ROAD) return CMD_ERROR;
-			if (HasVehicleOnTunnelBridge(tile, GetOtherTunnelBridgeEnd(tile))) return CMD_ERROR;
-			break;
+			CommandCost ret = TunnelBridgeIsFree(tile, GetOtherTunnelBridgeEnd(tile));
+			ret.SetGlobalErrorMessage();
+			if (ret.Failed()) return ret;
+		} break;
 
 		default:
 			return CMD_ERROR;
@@ -573,13 +575,15 @@ CommandCost CmdBuildRoad(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 			if (HasTileRoadType(tile, rt)) return_cmd_error(STR_ERROR_ALREADY_BUILT);
 		} break;
 
-		case MP_TUNNELBRIDGE:
+		case MP_TUNNELBRIDGE: {
 			if (GetTunnelBridgeTransportType(tile) != TRANSPORT_ROAD) goto do_clear;
 			if (MirrorRoadBits(DiagDirToRoadBits(GetTunnelBridgeDirection(tile))) != pieces) goto do_clear;
 			if (HasTileRoadType(tile, rt)) return_cmd_error(STR_ERROR_ALREADY_BUILT);
 			/* Don't allow adding roadtype to the bridge/tunnel when vehicles are already driving on it */
-			if (HasVehicleOnTunnelBridge(tile, GetOtherTunnelBridgeEnd(tile))) return CMD_ERROR;
-			break;
+			CommandCost ret = TunnelBridgeIsFree(tile, GetOtherTunnelBridgeEnd(tile));
+			ret.SetGlobalErrorMessage();
+			if (ret.Failed()) return ret;
+		} break;
 
 		default: {
 do_clear:;
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index 5723f3d478..c0575f9ecf 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -2342,7 +2342,7 @@ static void ClearPathReservation(const Train *v, TileIndex tile, Trackdir track_
 		if (GetTunnelBridgeDirection(tile) == ReverseDiagDir(dir)) {
 			TileIndex end = GetOtherTunnelBridgeEnd(tile);
 
-			if (!HasVehicleOnTunnelBridge(tile, end, v)) {
+			if (TunnelBridgeIsFree(tile, end, v).Succeeded()) {
 				/* Free the reservation only if no other train is on the tiles. */
 				SetTunnelBridgeReservation(tile, false);
 				SetTunnelBridgeReservation(end, false);
diff --git a/src/tunnelbridge_cmd.cpp b/src/tunnelbridge_cmd.cpp
index fdbfc8a67e..020b9f810d 100644
--- a/src/tunnelbridge_cmd.cpp
+++ b/src/tunnelbridge_cmd.cpp
@@ -611,7 +611,9 @@ static CommandCost DoClearTunnel(TileIndex tile, DoCommandFlag flags)
 
 	endtile = GetOtherTunnelEnd(tile);
 
-	if (HasVehicleOnTunnelBridge(tile, endtile)) return CMD_ERROR;
+	CommandCost ret = TunnelBridgeIsFree(tile, endtile);
+	ret.SetGlobalErrorMessage();
+	if (ret.Failed()) return ret;
 
 	_build_tunnel_endtile = endtile;
 
@@ -676,7 +678,9 @@ static CommandCost DoClearBridge(TileIndex tile, DoCommandFlag flags)
 
 	endtile = GetOtherBridgeEnd(tile);
 
-	if (HasVehicleOnTunnelBridge(tile, endtile)) return CMD_ERROR;
+	CommandCost ret = TunnelBridgeIsFree(tile, endtile);
+	ret.SetGlobalErrorMessage();
+	if (ret.Failed()) return ret;
 
 	direction = GetTunnelBridgeDirection(tile);
 	delta = TileOffsByDiagDir(direction);
diff --git a/src/vehicle.cpp b/src/vehicle.cpp
index 1a72220a85..9c32c14a69 100644
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -437,9 +437,9 @@ static Vehicle *GetVehicleTunnelBridgeProc(Vehicle *v, void *data)
  * @param tile first end
  * @param endtile second end
  * @param ignore Ignore this vehicle when searching
- * @return true if the bridge has a vehicle
+ * @return Succeeded command (if tunnel/bridge is free) or failed command (if a vehicle is using the tunnel/bridge).
  */
-bool HasVehicleOnTunnelBridge(TileIndex tile, TileIndex endtile, const Vehicle *ignore)
+CommandCost TunnelBridgeIsFree(TileIndex tile, TileIndex endtile, const Vehicle *ignore)
 {
 	/* Value v is not safe in MP games, however, it is used to generate a local
 	 * error message only (which may be different for different machines).
@@ -448,8 +448,8 @@ bool HasVehicleOnTunnelBridge(TileIndex tile, TileIndex endtile, const Vehicle *
 	Vehicle *v = VehicleFromPos(tile, (void *)ignore, &GetVehicleTunnelBridgeProc, true);
 	if (v == NULL) v = VehicleFromPos(endtile, (void *)ignore, &GetVehicleTunnelBridgeProc, true);
 
-	if (v != NULL) _error_message = STR_ERROR_TRAIN_IN_THE_WAY + v->type;
-	return v != NULL;
+	if (v != NULL) return_cmd_error(STR_ERROR_TRAIN_IN_THE_WAY + v->type);
+	return CommandCost();
 }
 
 
diff --git a/src/vehicle_func.h b/src/vehicle_func.h
index 7aa48bb3e7..82b465478c 100644
--- a/src/vehicle_func.h
+++ b/src/vehicle_func.h
@@ -46,7 +46,7 @@ CommandCost RefitVehicle(Vehicle *v, bool only_this, CargoID new_cid, byte new_s
 void ViewportAddVehicles(DrawPixelInfo *dpi);
 
 void ShowNewGrfVehicleError(EngineID engine, StringID part1, StringID part2, GRFBugs bug_type, bool critical);
-bool HasVehicleOnTunnelBridge(TileIndex tile, TileIndex endtile, const Vehicle *ignore = NULL);
+CommandCost TunnelBridgeIsFree(TileIndex tile, TileIndex endtile, const Vehicle *ignore = NULL);
 
 void DecreaseVehicleValue(Vehicle *v);
 void CheckVehicleBreakdown(Vehicle *v);