diff --git a/src/pathfinder/npf/aystar.cpp b/src/pathfinder/npf/aystar.cpp
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--- /dev/null
+++ b/src/pathfinder/npf/aystar.cpp
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+/* $Id$ */
+
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file aystar.cpp Implementation of A*. */
+
+/*
+ * This file has the core function for AyStar
+ *  AyStar is a fast pathfinding routine and is used for things like
+ *  AI_pathfinding and Train_pathfinding.
+ *  For more information about AyStar (A* Algorithm), you can look at
+ *    http://en.wikipedia.org/wiki/A-star_search_algorithm
+ */
+
+/*
+ * Friendly reminder:
+ *  Call (AyStar).free() when you are done with Aystar. It reserves a lot of memory
+ *  And when not free'd, it can cause system-crashes.
+ * Also remember that when you stop an algorithm before it is finished, your
+ * should call clear() yourself!
+ */
+
+#include "../../stdafx.h"
+#include "../../core/alloc_func.hpp"
+#include "aystar.h"
+
+int _aystar_stats_open_size;
+int _aystar_stats_closed_size;
+
+/* This looks in the Hash if a node exists in ClosedList
+ *  If so, it returns the PathNode, else NULL */
+static PathNode *AyStarMain_ClosedList_IsInList(AyStar *aystar, const AyStarNode *node)
+{
+	return (PathNode*)Hash_Get(&aystar->ClosedListHash, node->tile, node->direction);
+}
+
+/* This adds a node to the ClosedList
+ *  It makes a copy of the data */
+static void AyStarMain_ClosedList_Add(AyStar *aystar, const PathNode *node)
+{
+	/* Add a node to the ClosedList */
+	PathNode *new_node = MallocT<PathNode>(1);
+	*new_node = *node;
+	Hash_Set(&aystar->ClosedListHash, node->node.tile, node->node.direction, new_node);
+}
+
+/* Checks if a node is in the OpenList
+ *   If so, it returns the OpenListNode, else NULL */
+static OpenListNode *AyStarMain_OpenList_IsInList(AyStar *aystar, const AyStarNode *node)
+{
+	return (OpenListNode*)Hash_Get(&aystar->OpenListHash, node->tile, node->direction);
+}
+
+/* Gets the best node from OpenList
+ *  returns the best node, or NULL of none is found
+ * Also it deletes the node from the OpenList */
+static OpenListNode *AyStarMain_OpenList_Pop(AyStar *aystar)
+{
+	/* Return the item the Queue returns.. the best next OpenList item. */
+	OpenListNode *res = (OpenListNode*)aystar->OpenListQueue.pop(&aystar->OpenListQueue);
+	if (res != NULL) {
+		Hash_Delete(&aystar->OpenListHash, res->path.node.tile, res->path.node.direction);
+	}
+
+	return res;
+}
+
+/* Adds a node to the OpenList
+ *  It makes a copy of node, and puts the pointer of parent in the struct */
+static void AyStarMain_OpenList_Add(AyStar *aystar, PathNode *parent, const AyStarNode *node, int f, int g)
+{
+	/* Add a new Node to the OpenList */
+	OpenListNode *new_node = MallocT<OpenListNode>(1);
+	new_node->g = g;
+	new_node->path.parent = parent;
+	new_node->path.node = *node;
+	Hash_Set(&aystar->OpenListHash, node->tile, node->direction, new_node);
+
+	/* Add it to the queue */
+	aystar->OpenListQueue.push(&aystar->OpenListQueue, new_node, f);
+}
+
+/*
+ * Checks one tile and calculate his f-value
+ *  return values:
+ * AYSTAR_DONE : indicates we are done
+ */
+static int AyStarMain_CheckTile(AyStar *aystar, AyStarNode *current, OpenListNode *parent)
+{
+	int new_f, new_g, new_h;
+	PathNode *closedlist_parent;
+	OpenListNode *check;
+
+	/* Check the new node against the ClosedList */
+	if (AyStarMain_ClosedList_IsInList(aystar, current) != NULL) return AYSTAR_DONE;
+
+	/* Calculate the G-value for this node */
+	new_g = aystar->CalculateG(aystar, current, parent);
+	/* If the value was INVALID_NODE, we don't do anything with this node */
+	if (new_g == AYSTAR_INVALID_NODE) return AYSTAR_DONE;
+
+	/* There should not be given any other error-code.. */
+	assert(new_g >= 0);
+	/* Add the parent g-value to the new g-value */
+	new_g += parent->g;
+	if (aystar->max_path_cost != 0 && (uint)new_g > aystar->max_path_cost) return AYSTAR_DONE;
+
+	/* Calculate the h-value */
+	new_h = aystar->CalculateH(aystar, current, parent);
+	/* There should not be given any error-code.. */
+	assert(new_h >= 0);
+
+	/* The f-value if g + h */
+	new_f = new_g + new_h;
+
+	/* Get the pointer to the parent in the ClosedList (the currentone is to a copy of the one in the OpenList) */
+	closedlist_parent = AyStarMain_ClosedList_IsInList(aystar, &parent->path.node);
+
+	/* Check if this item is already in the OpenList */
+	check = AyStarMain_OpenList_IsInList(aystar, current);
+	if (check != NULL) {
+		uint i;
+		/* Yes, check if this g value is lower.. */
+		if (new_g > check->g) return AYSTAR_DONE;
+		aystar->OpenListQueue.del(&aystar->OpenListQueue, check, 0);
+		/* It is lower, so change it to this item */
+		check->g = new_g;
+		check->path.parent = closedlist_parent;
+		/* Copy user data, will probably have changed */
+		for (i = 0; i < lengthof(current->user_data); i++) {
+			check->path.node.user_data[i] = current->user_data[i];
+		}
+		/* Readd him in the OpenListQueue */
+		aystar->OpenListQueue.push(&aystar->OpenListQueue, check, new_f);
+	} else {
+		/* A new node, add him to the OpenList */
+		AyStarMain_OpenList_Add(aystar, closedlist_parent, current, new_f, new_g);
+	}
+
+	return AYSTAR_DONE;
+}
+
+/*
+ * This function is the core of AyStar. It handles one item and checks
+ *  his neighbour items. If they are valid, they are added to be checked too.
+ *  return values:
+ *   AYSTAR_EMPTY_OPENLIST : indicates all items are tested, and no path
+ *    has been found.
+ *   AYSTAR_LIMIT_REACHED : Indicates that the max_nodes limit has been
+ *    reached.
+ *   AYSTAR_FOUND_END_NODE : indicates we found the end. Path_found now is true, and in path is the path found.
+ *   AYSTAR_STILL_BUSY : indicates we have done this tile, did not found the path yet, and have items left to try.
+ */
+static int AyStarMain_Loop(AyStar *aystar)
+{
+	int i, r;
+
+	/* Get the best node from OpenList */
+	OpenListNode *current = AyStarMain_OpenList_Pop(aystar);
+	/* If empty, drop an error */
+	if (current == NULL) return AYSTAR_EMPTY_OPENLIST;
+
+	/* Check for end node and if found, return that code */
+	if (aystar->EndNodeCheck(aystar, current) == AYSTAR_FOUND_END_NODE) {
+		if (aystar->FoundEndNode != NULL)
+			aystar->FoundEndNode(aystar, current);
+		free(current);
+		return AYSTAR_FOUND_END_NODE;
+	}
+
+	/* Add the node to the ClosedList */
+	AyStarMain_ClosedList_Add(aystar, &current->path);
+
+	/* Load the neighbours */
+	aystar->GetNeighbours(aystar, current);
+
+	/* Go through all neighbours */
+	for (i = 0; i < aystar->num_neighbours; i++) {
+		/* Check and add them to the OpenList if needed */
+		r = aystar->checktile(aystar, &aystar->neighbours[i], current);
+	}
+
+	/* Free the node */
+	free(current);
+
+	if (aystar->max_search_nodes != 0 && Hash_Size(&aystar->ClosedListHash) >= aystar->max_search_nodes) {
+		/* We've expanded enough nodes */
+		return AYSTAR_LIMIT_REACHED;
+	} else {
+		/* Return that we are still busy */
+		return AYSTAR_STILL_BUSY;
+	}
+}
+
+/*
+ * This function frees the memory it allocated
+ */
+static void AyStarMain_Free(AyStar *aystar)
+{
+	aystar->OpenListQueue.free(&aystar->OpenListQueue, false);
+	/* 2nd argument above is false, below is true, to free the values only
+	 * once */
+	delete_Hash(&aystar->OpenListHash, true);
+	delete_Hash(&aystar->ClosedListHash, true);
+#ifdef AYSTAR_DEBUG
+	printf("[AyStar] Memory free'd\n");
+#endif
+}
+
+/*
+ * This function make the memory go back to zero
+ *  This function should be called when you are using the same instance again.
+ */
+void AyStarMain_Clear(AyStar *aystar)
+{
+	/* Clean the Queue, but not the elements within. That will be done by
+	 * the hash. */
+	aystar->OpenListQueue.clear(&aystar->OpenListQueue, false);
+	/* Clean the hashes */
+	clear_Hash(&aystar->OpenListHash, true);
+	clear_Hash(&aystar->ClosedListHash, true);
+
+#ifdef AYSTAR_DEBUG
+	printf("[AyStar] Cleared AyStar\n");
+#endif
+}
+
+/*
+ * This is the function you call to run AyStar.
+ *  return values:
+ *   AYSTAR_FOUND_END_NODE : indicates we found an end node.
+ *   AYSTAR_NO_PATH : indicates that there was no path found.
+ *   AYSTAR_STILL_BUSY : indicates we have done some checked, that we did not found the path yet, and that we still have items left to try.
+ * When the algorithm is done (when the return value is not AYSTAR_STILL_BUSY)
+ * aystar->clear() is called. Note that when you stop the algorithm halfway,
+ * you should still call clear() yourself!
+ */
+int AyStarMain_Main(AyStar *aystar)
+{
+	int r, i = 0;
+	/* Loop through the OpenList
+	 *  Quit if result is no AYSTAR_STILL_BUSY or is more than loops_per_tick */
+	while ((r = aystar->loop(aystar)) == AYSTAR_STILL_BUSY && (aystar->loops_per_tick == 0 || ++i < aystar->loops_per_tick)) { }
+#ifdef AYSTAR_DEBUG
+	switch (r) {
+		case AYSTAR_FOUND_END_NODE: printf("[AyStar] Found path!\n"); break;
+		case AYSTAR_EMPTY_OPENLIST: printf("[AyStar] OpenList run dry, no path found\n"); break;
+		case AYSTAR_LIMIT_REACHED:  printf("[AyStar] Exceeded search_nodes, no path found\n"); break;
+		default: break;
+	}
+#endif
+	if (r != AYSTAR_STILL_BUSY) {
+		/* We're done, clean up */
+		_aystar_stats_open_size = aystar->OpenListHash.size;
+		_aystar_stats_closed_size = aystar->ClosedListHash.size;
+		aystar->clear(aystar);
+	}
+
+	switch (r) {
+		case AYSTAR_FOUND_END_NODE: return AYSTAR_FOUND_END_NODE;
+		case AYSTAR_EMPTY_OPENLIST:
+		case AYSTAR_LIMIT_REACHED:  return AYSTAR_NO_PATH;
+		default:                    return AYSTAR_STILL_BUSY;
+	}
+}
+
+/*
+ * Adds a node from where to start an algorithm. Multiple nodes can be added
+ * if wanted. You should make sure that clear() is called before adding nodes
+ * if the AyStar has been used before (though the normal main loop calls
+ * clear() automatically when the algorithm finishes
+ * g is the cost for starting with this node.
+ */
+static void AyStarMain_AddStartNode(AyStar *aystar, AyStarNode *start_node, uint g)
+{
+#ifdef AYSTAR_DEBUG
+	printf("[AyStar] Starting A* Algorithm from node (%d, %d, %d)\n",
+		TileX(start_node->tile), TileY(start_node->tile), start_node->direction);
+#endif
+	AyStarMain_OpenList_Add(aystar, NULL, start_node, 0, g);
+}
+
+void init_AyStar(AyStar *aystar, Hash_HashProc hash, uint num_buckets)
+{
+	/* Allocated the Hash for the OpenList and ClosedList */
+	init_Hash(&aystar->OpenListHash, hash, num_buckets);
+	init_Hash(&aystar->ClosedListHash, hash, num_buckets);
+
+	/* Set up our sorting queue
+	 *  BinaryHeap allocates a block of 1024 nodes
+	 *  When thatone gets full it reserves an otherone, till this number
+	 *  That is why it can stay this high */
+	init_BinaryHeap(&aystar->OpenListQueue, 102400);
+
+	aystar->addstart  = AyStarMain_AddStartNode;
+	aystar->main      = AyStarMain_Main;
+	aystar->loop      = AyStarMain_Loop;
+	aystar->free      = AyStarMain_Free;
+	aystar->clear     = AyStarMain_Clear;
+	aystar->checktile = AyStarMain_CheckTile;
+}