diff --git a/src/ai/api/ai_tunnel.cpp b/src/ai/api/ai_tunnel.cpp
new file mode 100644
--- /dev/null
+++ b/src/ai/api/ai_tunnel.cpp
@@ -0,0 +1,119 @@
+/* $Id$ */
+
+/** @file ai_tunnel.cpp Implementation of AITunnel. */
+
+#include "ai_tunnel.hpp"
+#include "ai_map.hpp"
+#include "ai_rail.hpp"
+#include "../ai_instance.hpp"
+#include "../../openttd.h"
+#include "../../landscape.h"
+#include "../../tunnel_map.h"
+#include "../../road_type.h"
+#include "../../command_func.h"
+#include "../../tunnelbridge.h"
+#include "../../road_func.h"
+
+/* static */ bool AITunnel::IsTunnelTile(TileIndex tile)
+{
+	if (!::IsValidTile(tile)) return false;
+	return ::IsTunnelTile(tile);
+}
+
+/* static */ TileIndex AITunnel::GetOtherTunnelEnd(TileIndex tile)
+{
+	if (!::IsValidTile(tile)) return INVALID_TILE;
+
+	/* If it's a tunnel alread, take the easy way out! */
+	if (IsTunnelTile(tile)) return ::GetOtherTunnelEnd(tile);
+
+	::DoCommand(tile, 0, 0, DC_AUTO, CMD_BUILD_TUNNEL);
+	return _build_tunnel_endtile == 0 ? INVALID_TILE : _build_tunnel_endtile;
+}
+
+static void _DoCommandReturnBuildTunnel2(class AIInstance *instance)
+{
+	if (!AITunnel::_BuildTunnelRoad2()) {
+		AIObject::SetLastCommandRes(false);
+		AIInstance::DoCommandReturn(instance);
+		return;
+	}
+
+	/* This can never happen, as in test-mode this callback is never executed,
+	 *  and in execute-mode, the other callback is called. */
+	NOT_REACHED();
+}
+
+static void _DoCommandReturnBuildTunnel1(class AIInstance *instance)
+{
+	if (!AITunnel::_BuildTunnelRoad1()) {
+		AIObject::SetLastCommandRes(false);
+		AIInstance::DoCommandReturn(instance);
+		return;
+	}
+
+	/* This can never happen, as in test-mode this callback is never executed,
+	 *  and in execute-mode, the other callback is called. */
+	NOT_REACHED();
+}
+
+/* static */ bool AITunnel::BuildTunnel(AIVehicle::VehicleType vehicle_type, TileIndex start)
+{
+	EnforcePrecondition(false, ::IsValidTile(start));
+	EnforcePrecondition(false, vehicle_type == AIVehicle::VEHICLE_RAIL || vehicle_type == AIVehicle::VEHICLE_ROAD);
+	EnforcePrecondition(false, vehicle_type != AIVehicle::VEHICLE_RAIL || AIRail::IsRailTypeAvailable(AIRail::GetCurrentRailType()));
+
+	uint type = 0;
+	if (vehicle_type == AIVehicle::VEHICLE_ROAD) {
+		type |= (TRANSPORT_ROAD << 9);
+		type |= RoadTypeToRoadTypes((::RoadType)AIObject::GetRoadType());
+	} else {
+		type |= (TRANSPORT_RAIL << 9);
+		type |= AIRail::GetCurrentRailType();
+	}
+
+	/* For rail we do nothing special */
+	if (vehicle_type == AIVehicle::VEHICLE_RAIL) {
+		return AIObject::DoCommand(start, type, 0, CMD_BUILD_TUNNEL);
+	}
+
+	AIObject::SetCallbackVariable(0, start);
+	if (!AIObject::DoCommand(start, type, 0, CMD_BUILD_TUNNEL, NULL, &_DoCommandReturnBuildTunnel1)) return false;
+
+	/* In case of test-mode, test if we can build both road pieces */
+	return _BuildTunnelRoad1();
+}
+
+/* static */ bool AITunnel::_BuildTunnelRoad1()
+{
+	/* Build the piece of road on the 'start' side of the tunnel */
+	TileIndex end = AIObject::GetCallbackVariable(0);
+	TileIndex start = AITunnel::GetOtherTunnelEnd(end);
+
+	DiagDirection dir_1 = (DiagDirection)((::TileX(start) == ::TileX(end)) ? (::TileY(start) < ::TileY(end) ? DIAGDIR_NW : DIAGDIR_SE) : (::TileX(start) < ::TileX(end) ? DIAGDIR_NE : DIAGDIR_SW));
+	DiagDirection dir_2 = ::ReverseDiagDir(dir_1);
+
+	if (!AIObject::DoCommand(start + ::TileOffsByDiagDir(dir_1), ::DiagDirToRoadBits(dir_2) | (AIObject::GetRoadType() << 4), 0, CMD_BUILD_ROAD, NULL, &_DoCommandReturnBuildTunnel2)) return false;
+
+	/* In case of test-mode, test the other road piece too */
+	return _BuildTunnelRoad2();
+}
+
+/* static */ bool AITunnel::_BuildTunnelRoad2()
+{
+	/* Build the piece of road on the 'end' side of the tunnel */
+	TileIndex end = AIObject::GetCallbackVariable(0);
+	TileIndex start = AITunnel::GetOtherTunnelEnd(end);
+
+	DiagDirection dir_1 = (DiagDirection)((::TileX(start) == ::TileX(end)) ? (::TileY(start) < ::TileY(end) ? DIAGDIR_NW : DIAGDIR_SE) : (::TileX(start) < ::TileX(end) ? DIAGDIR_NE : DIAGDIR_SW));
+	DiagDirection dir_2 = ::ReverseDiagDir(dir_1);
+
+	return AIObject::DoCommand(end + ::TileOffsByDiagDir(dir_2), ::DiagDirToRoadBits(dir_1) | (AIObject::GetRoadType() << 4), 0, CMD_BUILD_ROAD);
+}
+
+/* static */ bool AITunnel::RemoveTunnel(TileIndex tile)
+{
+	EnforcePrecondition(false, IsTunnelTile(tile));
+
+	return AIObject::DoCommand(tile, 0, 0, CMD_LANDSCAPE_CLEAR);
+}