diff --git a/src/rail.cpp b/src/rail.cpp
new file mode 100644
--- /dev/null
+++ b/src/rail.cpp
@@ -0,0 +1,132 @@
+/* $Id$ */
+
+#include "stdafx.h"
+#include "openttd.h"
+#include "bridge_map.h"
+#include "rail.h"
+#include "station_map.h"
+#include "tunnel_map.h"
+
+/* XXX: Below 3 tables store duplicate data. Maybe remove some? */
+/* Maps a trackdir to the bit that stores its status in the map arrays, in the
+ * direction along with the trackdir */
+const byte _signal_along_trackdir[] = {
+	0x80, 0x80, 0x80, 0x20, 0x40, 0x10, 0, 0,
+	0x40, 0x40, 0x40, 0x10, 0x80, 0x20
+};
+
+/* Maps a trackdir to the bit that stores its status in the map arrays, in the
+ * direction against the trackdir */
+const byte _signal_against_trackdir[] = {
+	0x40, 0x40, 0x40, 0x10, 0x80, 0x20, 0, 0,
+	0x80, 0x80, 0x80, 0x20, 0x40, 0x10
+};
+
+/* Maps a Track to the bits that store the status of the two signals that can
+ * be present on the given track */
+const byte _signal_on_track[] = {
+	0xC0, 0xC0, 0xC0, 0x30, 0xC0, 0x30
+};
+
+/* Maps a diagonal direction to the all trackdirs that are connected to any
+ * track entering in this direction (including those making 90 degree turns)
+ */
+const TrackdirBits _exitdir_reaches_trackdirs[] = {
+	TRACKDIR_BIT_X_NE | TRACKDIR_BIT_LOWER_E | TRACKDIR_BIT_LEFT_N,  /* DIAGDIR_NE */
+	TRACKDIR_BIT_Y_SE | TRACKDIR_BIT_LEFT_S  | TRACKDIR_BIT_UPPER_E, /* DIAGDIR_SE */
+	TRACKDIR_BIT_X_SW | TRACKDIR_BIT_UPPER_W | TRACKDIR_BIT_RIGHT_S, /* DIAGDIR_SW */
+	TRACKDIR_BIT_Y_NW | TRACKDIR_BIT_RIGHT_N | TRACKDIR_BIT_LOWER_W  /* DIAGDIR_NW */
+};
+
+const Trackdir _next_trackdir[] = {
+	TRACKDIR_X_NE,  TRACKDIR_Y_SE,  TRACKDIR_LOWER_E, TRACKDIR_UPPER_E, TRACKDIR_RIGHT_S, TRACKDIR_LEFT_S, INVALID_TRACKDIR, INVALID_TRACKDIR,
+	TRACKDIR_X_SW,  TRACKDIR_Y_NW,  TRACKDIR_LOWER_W, TRACKDIR_UPPER_W, TRACKDIR_RIGHT_N, TRACKDIR_LEFT_N
+};
+
+/* Maps a trackdir to all trackdirs that make 90 deg turns with it. */
+const TrackdirBits _track_crosses_trackdirs[] = {
+	TRACKDIR_BIT_Y_SE     | TRACKDIR_BIT_Y_NW,                                                   /* TRACK_X     */
+	TRACKDIR_BIT_X_NE     | TRACKDIR_BIT_X_SW,                                                   /* TRACK_Y     */
+	TRACKDIR_BIT_RIGHT_N  | TRACKDIR_BIT_RIGHT_S  | TRACKDIR_BIT_LEFT_N  | TRACKDIR_BIT_LEFT_S,  /* TRACK_UPPER */
+	TRACKDIR_BIT_RIGHT_N  | TRACKDIR_BIT_RIGHT_S  | TRACKDIR_BIT_LEFT_N  | TRACKDIR_BIT_LEFT_S,  /* TRACK_LOWER */
+	TRACKDIR_BIT_UPPER_W  | TRACKDIR_BIT_UPPER_E  | TRACKDIR_BIT_LOWER_W | TRACKDIR_BIT_LOWER_E, /* TRACK_LEFT  */
+	TRACKDIR_BIT_UPPER_W  | TRACKDIR_BIT_UPPER_E  | TRACKDIR_BIT_LOWER_W | TRACKDIR_BIT_LOWER_E  /* TRACK_RIGHT */
+};
+
+/* Maps a track to all tracks that make 90 deg turns with it. */
+const TrackBits _track_crosses_tracks[] = {
+	TRACK_BIT_Y,    /* TRACK_X     */
+	TRACK_BIT_X,    /* TRACK_Y     */
+	TRACK_BIT_VERT, /* TRACK_UPPER */
+	TRACK_BIT_VERT, /* TRACK_LOWER */
+	TRACK_BIT_HORZ, /* TRACK_LEFT  */
+	TRACK_BIT_HORZ  /* TRACK_RIGHT */
+};
+
+/* Maps a trackdir to the (4-way) direction the tile is exited when following
+ * that trackdir */
+const DiagDirection _trackdir_to_exitdir[] = {
+	DIAGDIR_NE,DIAGDIR_SE,DIAGDIR_NE,DIAGDIR_SE,DIAGDIR_SW,DIAGDIR_SE, DIAGDIR_NE,DIAGDIR_NE,
+	DIAGDIR_SW,DIAGDIR_NW,DIAGDIR_NW,DIAGDIR_SW,DIAGDIR_NW,DIAGDIR_NE,
+};
+
+const Trackdir _track_exitdir_to_trackdir[][DIAGDIR_END] = {
+	{TRACKDIR_X_NE,     INVALID_TRACKDIR,  TRACKDIR_X_SW,     INVALID_TRACKDIR},
+	{INVALID_TRACKDIR,  TRACKDIR_Y_SE,     INVALID_TRACKDIR,  TRACKDIR_Y_NW},
+	{TRACKDIR_UPPER_E,  INVALID_TRACKDIR,  INVALID_TRACKDIR,  TRACKDIR_UPPER_W},
+	{INVALID_TRACKDIR,  TRACKDIR_LOWER_E,  TRACKDIR_LOWER_W,  INVALID_TRACKDIR},
+	{INVALID_TRACKDIR,  INVALID_TRACKDIR,  TRACKDIR_LEFT_S,   TRACKDIR_LEFT_N},
+	{TRACKDIR_RIGHT_N,  TRACKDIR_RIGHT_S,  INVALID_TRACKDIR,  INVALID_TRACKDIR}
+};
+
+const Trackdir _track_enterdir_to_trackdir[][DIAGDIR_END] = { // TODO: replace magic with enums
+	{TRACKDIR_X_NE,     INVALID_TRACKDIR,  TRACKDIR_X_SW,     INVALID_TRACKDIR},
+	{INVALID_TRACKDIR,  TRACKDIR_Y_SE,     INVALID_TRACKDIR,  TRACKDIR_Y_NW},
+	{INVALID_TRACKDIR,  TRACKDIR_UPPER_E,  TRACKDIR_UPPER_W,  INVALID_TRACKDIR},
+	{TRACKDIR_LOWER_E,  INVALID_TRACKDIR,  INVALID_TRACKDIR,  TRACKDIR_LOWER_W},
+	{TRACKDIR_LEFT_N,   TRACKDIR_LEFT_S,   INVALID_TRACKDIR,  INVALID_TRACKDIR},
+	{INVALID_TRACKDIR,  INVALID_TRACKDIR,  TRACKDIR_RIGHT_S,  TRACKDIR_RIGHT_N}
+};
+
+const Trackdir _track_direction_to_trackdir[][DIR_END] = {
+	{INVALID_TRACKDIR, TRACKDIR_X_NE,     INVALID_TRACKDIR, INVALID_TRACKDIR,  INVALID_TRACKDIR, TRACKDIR_X_SW,     INVALID_TRACKDIR, INVALID_TRACKDIR},
+	{INVALID_TRACKDIR, INVALID_TRACKDIR,  INVALID_TRACKDIR, TRACKDIR_Y_SE,     INVALID_TRACKDIR, INVALID_TRACKDIR,  INVALID_TRACKDIR, TRACKDIR_Y_NW},
+	{INVALID_TRACKDIR, INVALID_TRACKDIR,  TRACKDIR_UPPER_E, INVALID_TRACKDIR,  INVALID_TRACKDIR, INVALID_TRACKDIR,  TRACKDIR_UPPER_W, INVALID_TRACKDIR},
+	{INVALID_TRACKDIR, INVALID_TRACKDIR,  TRACKDIR_LOWER_E, INVALID_TRACKDIR,  INVALID_TRACKDIR, INVALID_TRACKDIR,  TRACKDIR_LOWER_W, INVALID_TRACKDIR},
+	{TRACKDIR_LEFT_N,  INVALID_TRACKDIR,  INVALID_TRACKDIR, INVALID_TRACKDIR,  TRACKDIR_LEFT_S,  INVALID_TRACKDIR,  INVALID_TRACKDIR, INVALID_TRACKDIR},
+	{TRACKDIR_RIGHT_N, INVALID_TRACKDIR,  INVALID_TRACKDIR, INVALID_TRACKDIR,  TRACKDIR_RIGHT_S, INVALID_TRACKDIR,  INVALID_TRACKDIR, INVALID_TRACKDIR}
+};
+
+const Trackdir _dir_to_diag_trackdir[] = {
+	TRACKDIR_X_NE, TRACKDIR_Y_SE, TRACKDIR_X_SW, TRACKDIR_Y_NW,
+};
+
+
+RailType GetTileRailType(TileIndex tile, Trackdir trackdir)
+{
+	switch (GetTileType(tile)) {
+		case MP_RAILWAY:
+			return GetRailType(tile);
+
+		case MP_STREET:
+			/* rail/road crossing */
+			if (IsLevelCrossing(tile)) return GetRailTypeCrossing(tile);
+			break;
+
+		case MP_STATION:
+			if (IsRailwayStationTile(tile)) return GetRailType(tile);
+			break;
+
+		case MP_TUNNELBRIDGE:
+			if (IsTunnel(tile)) {
+				if (GetTunnelTransportType(tile) == TRANSPORT_RAIL) return GetRailType(tile);
+			} else {
+				if (GetBridgeTransportType(tile) == TRANSPORT_RAIL) return GetRailType(tile);
+			}
+			break;
+
+		default:
+			break;
+	}
+	return INVALID_RAILTYPE;
+}