--- a/bin/ai/regression/regression.nut	Thu Jun 12 10:34:21 2008 +0000
+++ b/bin/ai/regression/regression.nut	Thu Jun 12 11:15:59 2008 +0000
@@ -619,7 +619,9 @@
 	print("  BuildDock():          " + AIMarine.BuildDock(29253));
 	print("  BuildBuoy():          " + AIMarine.BuildBuoy(28481));
 	print("  BuildLock():          " + AIMarine.BuildLock(28487));
+	print("  HasTransportType():   " + AITile.HasTransportType(32127, AITile.TRANSPORT_WATER));
 	print("  BuildCanal():         " + AIMarine.BuildCanal(32127));
+	print("  HasTransportType():   " + AITile.HasTransportType(32127, AITile.TRANSPORT_WATER));
 	print("  IsWaterDepotTile():   " + AIMarine.IsWaterDepotTile(28479));
 	print("  IsDockTile():         " + AIMarine.IsDockTile(29253));
 	print("  IsBuoyTile():         " + AIMarine.IsBuoyTile(28481));
@@ -766,7 +768,9 @@
 	print("    IsRoadTile():                  " + AIRoad.IsRoadTile(33411));
 	print("    BuildRoad():                   " + AIRoad.BuildRoad(0, 1));
 	print("    BuildRoad():                   " + AIRoad.BuildRoad(33411, 33411));
+	print("    HasTransportType():            " + AITile.HasTransportType(33413, AITile.TRANSPORT_ROAD));
 	print("    BuildRoad():                   " + AIRoad.BuildRoad(33411, 33414));
+	print("    HasTransportType():            " + AITile.HasTransportType(33413, AITile.TRANSPORT_ROAD));
 	print("    AreRoadTilesConnected():       " + AIRoad.AreRoadTilesConnected(33412, 33413));
 	print("    IsRoadTile():                  " + AIRoad.IsRoadTile(33411));
 	print("    HasRoadType(Road):             " + AIRoad.HasRoadType(33411, AIRoad.ROADTYPE_ROAD));

--- a/bin/ai/regression/regression.txt	Thu Jun 12 10:34:21 2008 +0000
+++ b/bin/ai/regression/regression.txt	Thu Jun 12 11:15:59 2008 +0000
@@ -5696,7 +5696,9 @@
   BuildDock():          true
   BuildBuoy():          true
   BuildLock():          true
+  HasTransportType():   false
   BuildCanal():         true
+  HasTransportType():   true
   IsWaterDepotTile():   true
   IsDockTile():         true
   IsBuoyTile():         true
@@ -5764,7 +5766,9 @@
     IsRoadTile():                  false
     BuildRoad():                   false
     BuildRoad():                   false
+    HasTransportType():            false
     BuildRoad():                   true
+    HasTransportType():            true
     AreRoadTilesConnected():       true
     IsRoadTile():                  true
     HasRoadType(Road):             true

--- a/src/ai/api/ai_tile.cpp	Thu Jun 12 10:34:21 2008 +0000
+++ b/src/ai/api/ai_tile.cpp	Thu Jun 12 11:15:59 2008 +0000
@@ -7,6 +7,7 @@
 #include "ai_town.hpp"
 #include "../../openttd.h"
 #include "../../tile_map.h"
+#include "../../tile_cmd.h"
 #include "../../map_func.h"
 #include "../../variables.h"
 #include "../../station_func.h"
@@ -113,6 +114,13 @@
 	return AICompany::ResolveCompanyID((AICompany::CompanyID)(byte)::GetTileOwner(tile));
 }
 
+/* static */ bool AITile::HasTransportType(TileIndex tile, TransportType transport_type)
+{
+	if (!::IsValidTile(tile)) return false;
+
+	return GB(::GetTileTrackStatus(tile, (::TransportType)transport_type, UINT32_MAX), 0, 16) != 0;
+}
+
 /* static */ int32 AITile::GetCargoAcceptance(TileIndex tile, CargoID cargo_type, uint width, uint height, uint radius)
 {
 	if (!::IsValidTile(tile)) return false;

--- a/src/ai/api/ai_tile.hpp	Thu Jun 12 10:34:21 2008 +0000
+++ b/src/ai/api/ai_tile.hpp	Thu Jun 12 11:15:59 2008 +0000
@@ -39,6 +39,7 @@
 	 *  is the north-part of the tile.
 	 */
 	enum Slope {
+		/* Values are important, as they represent the internal state of the game. */
 		SLOPE_FLAT     = 0x00,                                  //!< A flat tile
 		SLOPE_W        = 0x01,                                  //!< The west corner of the tile is raised
 		SLOPE_S        = 0x02,                                  //!< The south corner of the tile is raised
@@ -65,6 +66,19 @@
 	};
 
 	/**
+	 * The different transport types a tile can have.
+	 */
+	enum TransportType {
+		/* Values are important, as they represent the internal state of the game. */
+		TRANSPORT_RAIL    =  0, //!< Tile with rail.
+		TRANSPORT_ROAD    =  1, //!< Tile with road.
+		TRANSPORT_WATER   =  2, //!< Tile with navigable waterways.
+		TRANSPORT_AIR     =  3, //!< Tile with airport.
+
+		INVALID_TRANSPORT = -1, //!< Tile without any transport type.
+	};
+
+	/**
 	 * Check if this tile is buildable, i.e. no things on it that needs
 	 *  demolishing.
 	 * @param tile The tile to check on.
@@ -158,6 +172,20 @@
 	static AICompany::CompanyID GetOwner(TileIndex tile);
 
 	/**
+	 * Checks whether the given tile contains parts suitable for the given
+	 *  TransportType.
+	 * @param tile The tile to check.
+	 * @param transport_type The TransportType to check against.
+	 * @pre AIMap::IsValidTile(tile).
+	 * @note Returns false on tiles with roadworks and on road tiles with only
+	 *       a single piece of road as these tiles cannot be used to transport
+	 *       anything on. It furthermore returns true on some coast tile for
+	 *       TRANSPORT_WATER because ships can navigate over them.
+	 * @return True if and only if the tile has the given TransportType.
+	 */
+	static bool HasTransportType(TileIndex tile, TransportType transport_type);
+
+	/**
 	 * Check how much cargo this tile accepts.
 	 *  It creates a radius around the tile, and adds up all acceptance of this
 	 *   cargo.

--- a/src/ai/api/ai_tile.hpp.sq	Thu Jun 12 10:34:21 2008 +0000
+++ b/src/ai/api/ai_tile.hpp.sq	Thu Jun 12 11:15:59 2008 +0000
@@ -9,6 +9,8 @@
 	template <> int Return<AITile::ErrorMessages>(HSQUIRRELVM vm, AITile::ErrorMessages res) { sq_pushinteger(vm, (int32)res); return 1; }
 	template <> AITile::Slope GetParam(ForceType<AITile::Slope>, HSQUIRRELVM vm, int index, SQAutoFreePointers *ptr) { SQInteger tmp; sq_getinteger(vm, index, &tmp); return (AITile::Slope)tmp; }
 	template <> int Return<AITile::Slope>(HSQUIRRELVM vm, AITile::Slope res) { sq_pushinteger(vm, (int32)res); return 1; }
+	template <> AITile::TransportType GetParam(ForceType<AITile::TransportType>, HSQUIRRELVM vm, int index, SQAutoFreePointers *ptr) { SQInteger tmp; sq_getinteger(vm, index, &tmp); return (AITile::TransportType)tmp; }
+	template <> int Return<AITile::TransportType>(HSQUIRRELVM vm, AITile::TransportType res) { sq_pushinteger(vm, (int32)res); return 1; }
 
 	/* Allow AITile to be used as Squirrel parameter */
 	template <> AITile *GetParam(ForceType<AITile *>, HSQUIRRELVM vm, int index, SQAutoFreePointers *ptr) { SQUserPointer instance; sq_getinstanceup(vm, index, &instance, 0); return  (AITile *)instance; }
@@ -48,6 +50,11 @@
 	SQAITile.DefSQConst(engine, AITile::SLOPE_STEEP_E,     "SLOPE_STEEP_E");
 	SQAITile.DefSQConst(engine, AITile::SLOPE_STEEP_N,     "SLOPE_STEEP_N");
 	SQAITile.DefSQConst(engine, AITile::SLOPE_INVALID,     "SLOPE_INVALID");
+	SQAITile.DefSQConst(engine, AITile::TRANSPORT_RAIL,    "TRANSPORT_RAIL");
+	SQAITile.DefSQConst(engine, AITile::TRANSPORT_ROAD,    "TRANSPORT_ROAD");
+	SQAITile.DefSQConst(engine, AITile::TRANSPORT_WATER,   "TRANSPORT_WATER");
+	SQAITile.DefSQConst(engine, AITile::TRANSPORT_AIR,     "TRANSPORT_AIR");
+	SQAITile.DefSQConst(engine, AITile::INVALID_TRANSPORT, "INVALID_TRANSPORT");
 
 	AIError::RegisterErrorMap(STR_1003_ALREADY_AT_SEA_LEVEL, AITile::ERR_TILE_TOO_HIGH);
 	AIError::RegisterErrorMap(STR_1003_ALREADY_AT_SEA_LEVEL, AITile::ERR_TILE_TOO_LOW);
@@ -66,6 +73,7 @@
 	SQAITile.DefSQStaticMethod(engine, &AITile::GetComplementSlope,         "GetComplementSlope",         2, "xi");
 	SQAITile.DefSQStaticMethod(engine, &AITile::GetHeight,                  "GetHeight",                  2, "xi");
 	SQAITile.DefSQStaticMethod(engine, &AITile::GetOwner,                   "GetOwner",                   2, "xi");
+	SQAITile.DefSQStaticMethod(engine, &AITile::HasTransportType,           "HasTransportType",           3, "xii");
 	SQAITile.DefSQStaticMethod(engine, &AITile::GetCargoAcceptance,         "GetCargoAcceptance",         6, "xiiiii");
 	SQAITile.DefSQStaticMethod(engine, &AITile::GetCargoProduction,         "GetCargoProduction",         6, "xiiiii");
 	SQAITile.DefSQStaticMethod(engine, &AITile::GetDistanceManhattanToTile, "GetDistanceManhattanToTile", 3, "xii");