Index: src/airport_gui.cpp
===================================================================
--- src/airport_gui.cpp	(revision 9518)
+++ src/airport_gui.cpp	(working copy)
@@ -18,6 +18,7 @@
 #include "station.h"
 #include "airport.h"
 #include "depot.h"
+#include "engine.h"
 
 static byte _selected_airport_type;
 
@@ -34,7 +35,13 @@
 
 static void PlaceAirport(TileIndex tile)
 {
-	DoCommandP(tile, _selected_airport_type, 0, CcBuildAirport, CMD_BUILD_AIRPORT | CMD_AUTO | CMD_NO_WATER | CMD_MSG(STR_A001_CAN_T_BUILD_AIRPORT_HERE));
+	if(IsEngineAvailable(VEH_AIRCRAFT)) {
+		DoCommandP(tile, _selected_airport_type, 0, CcBuildAirport, CMD_BUILD_AIRPORT | CMD_AUTO | CMD_NO_WATER | CMD_MSG(STR_A001_CAN_T_BUILD_AIRPORT_HERE));
+	}
+	else
+	{
+		ShowErrorMessage(INVALID_STRING_ID, STR_CANT_BUILD_AIRPORT_YET, 0, 0);
+	}
 }
 
 static void PlaceAir_DemolishArea(TileIndex tile)
Index: src/dock_gui.cpp
===================================================================
--- src/dock_gui.cpp	(revision 9518)
+++ src/dock_gui.cpp	(working copy)
@@ -16,6 +16,7 @@
 #include "sound.h"
 #include "command.h"
 #include "variables.h"
+#include "engine.h"
 
 static void ShowBuildDockStationPicker();
 static void ShowBuildDocksDepotPicker();
@@ -38,17 +39,35 @@
 
 static void PlaceDocks_Dock(TileIndex tile)
 {
-	DoCommandP(tile, 0, 0, CcBuildDocks, CMD_BUILD_DOCK | CMD_AUTO | CMD_MSG(STR_9802_CAN_T_BUILD_DOCK_HERE));
+	if(IsEngineAvailable(VEH_SHIP)) {
+		DoCommandP(tile, 0, 0, CcBuildDocks, CMD_BUILD_DOCK | CMD_AUTO | CMD_MSG(STR_9802_CAN_T_BUILD_DOCK_HERE));
+	}
+	else
+	{
+		ShowErrorMessage(INVALID_STRING_ID, STR_CANT_BUILD_DOCK_YET, 0, 0);
+	}
 }
 
 static void PlaceDocks_Depot(TileIndex tile)
 {
-	DoCommandP(tile, _ship_depot_direction, 0, CcBuildDocks, CMD_BUILD_SHIP_DEPOT | CMD_AUTO | CMD_MSG(STR_3802_CAN_T_BUILD_SHIP_DEPOT));
+	if(IsEngineAvailable(VEH_SHIP)) {
+		DoCommandP(tile, _ship_depot_direction, 0, CcBuildDocks, CMD_BUILD_SHIP_DEPOT | CMD_AUTO | CMD_MSG(STR_3802_CAN_T_BUILD_SHIP_DEPOT));
+	}
+	else
+	{
+		ShowErrorMessage(INVALID_STRING_ID, STR_CANT_BUILD_SHIPDEPOT_YET, 0, 0);
+	}
 }
 
 static void PlaceDocks_Buoy(TileIndex tile)
 {
-	DoCommandP(tile, 0, 0, CcBuildDocks, CMD_BUILD_BUOY | CMD_AUTO | CMD_MSG(STR_9835_CAN_T_POSITION_BUOY_HERE));
+	if(IsEngineAvailable(VEH_SHIP)) {
+		DoCommandP(tile, 0, 0, CcBuildDocks, CMD_BUILD_BUOY | CMD_AUTO | CMD_MSG(STR_9835_CAN_T_POSITION_BUOY_HERE));
+	}
+	else
+	{
+		ShowErrorMessage(INVALID_STRING_ID, STR_CANT_BUILD_BUOY_YET, 0, 0);
+	}
 }
 
 static void PlaceDocks_DemolishArea(TileIndex tile)
Index: src/engine.cpp
===================================================================
--- src/engine.cpp	(revision 9518)
+++ src/engine.cpp	(working copy)
@@ -348,6 +348,24 @@
 	}
 }
 
+bool IsEngineAvailable(uint32 engineType)
+{
+
+	Engine *e;
+
+	for(e = _engines; e != endof(_engines); e++) {
+
+		if(e->type == engineType && e->player_avail) {
+			return true;
+		}
+
+	}
+
+	return false;
+
+}
+
+
 /** Rename an engine.
  * @param tile unused
  * @param p1 engine ID to rename
Index: src/engine.h
===================================================================
--- src/engine.h	(revision 9518)
+++ src/engine.h	(working copy)
@@ -153,6 +153,7 @@
 void DeleteCustomEngineNames();
 
 bool IsEngineBuildable(EngineID engine, byte type, PlayerID player);
+bool IsEngineAvailable(uint32 engineType);
 
 enum {
 	NUM_NORMAL_RAIL_ENGINES = 54,
Index: src/lang/english.txt
===================================================================
--- src/lang/english.txt	(revision 9518)
+++ src/lang/english.txt	(working copy)
@@ -3149,3 +3149,9 @@
 ########
 
 STR_FEEDER_CARGO_VALUE                                          :{BLACK}Transfer Credits: {LTBLUE}{CURRENCY}
+
+STR_CANT_BUILD_AIRPORT_YET										:{WHITE}No aircraft available to build an airport for!
+STR_CANT_BUILD_DOCK_YET											:{WHITE}No ships available to build a dock for!
+STR_CANT_BUILD_SHIPDEPOT_YET									:{WHITE}No ships available to build a depot for!
+STR_CANT_BUILD_BUOY_YET											:{WHITE}No ships available to build a buoy for!
+STR_CANT_BUILD_VEHICLEDEPOT_YET									:{WHITE}No road vehicles available to build a depot for!
Index: src/lang/german.txt
===================================================================
--- src/lang/german.txt	(revision 9518)
+++ src/lang/german.txt	(working copy)
@@ -3147,3 +3147,9 @@
 ########
 
 STR_FEEDER_CARGO_VALUE                                          :{BLACK}Überweise Geld: {LTBLUE}{CURRENCY}
+
+STR_CANT_BUILD_AIRPORT_YET										:{WHITE}Flughafen kann nicht gebaut werden - es existieren zu dieser Zeit noch keine Flugzeuge!
+STR_CANT_BUILD_DOCK_YET											:{WHITE}Dock kann nicht gebaut werden - es existieren zu dieser Zeit noch keine Schiffe!
+STR_CANT_BUILD_SHIPDEPOT_YET									:{WHITE}Schiffsdepot kann nicht gebaut werden - es existieren zu dieser Zeit noch keine Schiffe!
+STR_CANT_BUILD_BUOY_YET											:{WHITE}Boje kann nicht gebaut werden - es existieren zu dieser Zeit noch keine Schiffe!
+STR_CANT_BUILD_VEHICLEDEPOT_YET									:{WHITE}Fahrzeug-Depot kann nicht gebaut werden - es existieren zu dieser Zeit noch keine Strassenfahrzeuge!
Index: src/road_gui.cpp
===================================================================
--- src/road_gui.cpp	(revision 9518)
+++ src/road_gui.cpp	(working copy)
@@ -92,7 +92,13 @@
 
 static void PlaceRoad_Depot(TileIndex tile)
 {
-	DoCommandP(tile, _road_depot_orientation, 0, CcRoadDepot, CMD_BUILD_ROAD_DEPOT | CMD_AUTO | CMD_NO_WATER | CMD_MSG(STR_1807_CAN_T_BUILD_ROAD_VEHICLE));
+	if(IsEngineAvailable(VEH_ROAD)) {
+		DoCommandP(tile, _road_depot_orientation, 0, CcRoadDepot, CMD_BUILD_ROAD_DEPOT | CMD_AUTO | CMD_NO_WATER | CMD_MSG(STR_1807_CAN_T_BUILD_ROAD_VEHICLE));
+	}
+	else
+	{
+		ShowErrorMessage(INVALID_STRING_ID, STR_CANT_BUILD_VEHICLEDEPOT_YET, 0, 0);
+	}
 }
 
 static void PlaceRoadStop(TileIndex tile, uint32 p2, uint32 cmd)