Index: src/station_cmd.cpp
===================================================================
--- src/station_cmd.cpp	(revision 27653)
+++ src/station_cmd.cpp	(working copy)
@@ -12,6 +12,7 @@
 #include "stdafx.h"
 #include "aircraft.h"
 #include "bridge_map.h"
+#include "tunnelbridge_map.h"
 #include "cmd_helper.h"
 #include "viewport_func.h"
 #include "command_func.h"
@@ -2500,8 +2501,14 @@
 	if (ret.Failed()) return ret;
 
 	tile_cur += TileOffsByDiagDir(direction);
-	if (!IsTileType(tile_cur, MP_WATER) || !IsTileFlat(tile_cur)) {
-		return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
+	if (IsTileType(tile_cur, MP_TUNNELBRIDGE)) {
+		if (GetTunnelBridgeTransportType(tile_cur) != TRANSPORT_WATER) {
+			return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
+		}
+	} else {
+		if (!IsTileType(tile_cur, MP_WATER) && !IsBuoyTile(tile_cur) || !IsTileFlat(tile_cur) && !IsSlopeWithOneCornerRaised(GetTileSlope(tile_cur))) {
+			return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
+		}
 	}
 
 	TileArea dock_area = TileArea(tile + ToTileIndexDiff(_dock_tileoffs_chkaround[direction]),
Index: src/waypoint_cmd.cpp
===================================================================
--- src/waypoint_cmd.cpp	(revision 27653)
+++ src/waypoint_cmd.cpp	(working copy)
@@ -297,12 +297,15 @@
 	Waypoint *wp = FindDeletedWaypointCloseTo(tile, STR_SV_STNAME_BUOY, OWNER_NONE);
 	if (wp == NULL && !Waypoint::CanAllocateItem()) return_cmd_error(STR_ERROR_TOO_MANY_STATIONS_LOADING);
 
+	CommandCost ret;
 	CommandCost cost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_WAYPOINT_BUOY]);
 	if (!IsWaterTile(tile)) {
-		CommandCost ret = DoCommand(tile, 0, 0, flags | DC_AUTO, CMD_LANDSCAPE_CLEAR);
+		ret = DoCommand(tile, 0, 0, flags | DC_AUTO, CMD_LANDSCAPE_CLEAR);
 		if (ret.Failed()) return ret;
 		cost.AddCost(ret);
 	}
+	ret = EnsureNoVehicleOnGround(tile);
+	if (ret.Failed()) return ret;
 
 	if (flags & DC_EXEC) {
 		if (wp == NULL) {