diff -r e782b59f1f6a -r d2a6acdbd665 src/station_cmd.cpp
--- a/src/station_cmd.cpp	Sun Sep 09 21:14:29 2007 +0000
+++ b/src/station_cmd.cpp	Sun Sep 23 07:37:38 2007 +0000
@@ -42,6 +42,7 @@
 #include "road.h"
 #include "cargotype.h"
 #include "strings.h"
+#include "autoslope.h"
 
 DEFINE_OLD_POOL_GENERIC(Station, Station)
 DEFINE_OLD_POOL_GENERIC(RoadStop, RoadStop)
@@ -375,7 +376,14 @@
 	}
 }
 
-// Update the station virt coords while making the modified parts dirty.
+/**
+ * Update the station virt coords while making the modified parts dirty.
+ *
+ * This function updates the virt coords and mark the modified parts as dirty
+ *
+ * @param st The station to update the virt coords
+ * @ingroup dirty
+ */
 static void UpdateStationVirtCoordDirty(Station *st)
 {
 	st->MarkDirty();
@@ -1227,22 +1235,14 @@
  */
 CommandCost DoConvertStationRail(TileIndex tile, RailType totype, bool exec)
 {
-	const Station* st = GetStationByTile(tile);
-
-	if (!CheckOwnership(st->owner) || !EnsureNoVehicle(tile)) return CMD_ERROR;
-
-	// tile is not a railroad station?
+	/* Tile is not a railroad station? */
 	if (!IsRailwayStation(tile)) return CMD_ERROR;
 
-	if (GetRailType(tile) == totype) return CMD_ERROR;
-
-	// 'hidden' elrails can't be downgraded to normal rail when elrails are disabled
-	if (_patches.disable_elrails && totype == RAILTYPE_RAIL && GetRailType(tile) == RAILTYPE_ELECTRIC) return CMD_ERROR;
-
 	if (exec) {
 		SetRailType(tile, totype);
 		MarkTileDirtyByTile(tile);
 		YapfNotifyTrackLayoutChange(tile, GetRailStationTrack(tile));
+		VehicleFromPos(tile, &tile, UpdateTrainPowerProc);
 	}
 
 	return CommandCost(_price.build_rail / 2);
@@ -2881,6 +2881,36 @@
 
 static CommandCost TerraformTile_Station(TileIndex tile, uint32 flags, uint z_new, Slope tileh_new)
 {
+	if (_patches.build_on_slopes && AutoslopeEnabled()) {
+		/* TODO: If you implement newgrf callback 149 'land slope check', you have to decide what to do with it here.
+		 *       TTDP does not call it.
+		 */
+		if (!IsSteepSlope(tileh_new) && (GetTileMaxZ(tile) == z_new + GetSlopeMaxZ(tileh_new))) {
+			switch (GetStationType(tile)) {
+				case STATION_RAIL: {
+					DiagDirection direction = AxisToDiagDir(GetRailStationAxis(tile));
+					if (!AutoslopeCheckForEntranceEdge(tile, z_new, tileh_new, direction)) break;
+					if (!AutoslopeCheckForEntranceEdge(tile, z_new, tileh_new, ReverseDiagDir(direction))) break;
+					return _price.terraform;
+				}
+
+				case STATION_AIRPORT:
+					return _price.terraform;
+
+				case STATION_TRUCK:
+				case STATION_BUS: {
+					DiagDirection direction = GetRoadStopDir(tile);
+					if (!AutoslopeCheckForEntranceEdge(tile, z_new, tileh_new, direction)) break;
+					if (IsDriveThroughStopTile(tile)) {
+						if (!AutoslopeCheckForEntranceEdge(tile, z_new, tileh_new, ReverseDiagDir(direction))) break;
+					}
+					return _price.terraform;
+				}
+
+				default: break;
+			}
+		}
+	}
 	return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
 }