+template<>
+const set<Terrain *> &Layout::get_all<Terrain>() const
+{
+ return objects.get<Terrain>();
+}
+
+template<>
+const set<TrackChain *> &Layout::get_all<TrackChain>() const
+{
+ return track_chains.get();
+}
+
+template<>
+const set<Block *> &Layout::get_all<Block>() const
+{
+ return track_chains.get<Block>();
+}
+
+template<>
+const set<Route *> &Layout::get_all<Route>() const
+{
+ return track_chains.get<Route>();
+}
+
+template<>
+const set<Zone *> &Layout::get_all<Zone>() const
+{
+ return track_chains.get<Zone>();
+}
+
+template<>
+const set<Sensor *> &Layout::get_all<Sensor>() const
+{
+ return sensors.get<Sensor>();
+}
+
+template<>
+const set<TrackCircuit *> &Layout::get_all<TrackCircuit>() const
+{
+ return sensors.get<TrackCircuit>();
+}
+
+template<>
+const set<BeamGate *> &Layout::get_all<BeamGate>() const
+{
+ return sensors.get<BeamGate>();
+}
+