diff --git a/libs/ardour/ardour/route.h b/libs/ardour/ardour/route.h
index 9d785e7341..6dbdda496c 100644
--- a/libs/ardour/ardour/route.h
+++ b/libs/ardour/ardour/route.h
@@ -287,6 +287,21 @@ class LIBARDOUR_API Route : public SessionObject, public Automatable, public Rou
 	PBD::Signal1<void,void*> mute_changed;
 	PBD::Signal0<void>       mute_points_changed;
 
+	/** track numbers - assigned by session
+	 * nubers > 0 indicate tracks (audio+midi)
+	 * nubers < 0 indicate busses
+	 * zero is reserved for unnumbered special busses.
+	 * */
+	PBD::Signal0<void> track_number_changed;
+	int64_t track_number() const { return _track_number; }
+
+	void set_track_number(int64_t tn) {
+		if (tn == _track_number) { return; }
+		_track_number = tn;
+		track_number_changed();
+		PropertyChanged (ARDOUR::Properties::name);
+	}
+
 	/** the processors have changed; the parameter indicates what changed */
 	PBD::Signal1<void,RouteProcessorChange> processors_changed;
 	PBD::Signal1<void,void*> record_enable_changed;
@@ -562,6 +577,8 @@ class LIBARDOUR_API Route : public SessionObject, public Automatable, public Rou
 	bool _has_order_key;
         uint32_t _remote_control_id;
 
+	int64_t _track_number;
+
 	void input_change_handler (IOChange, void *src);
 	void output_change_handler (IOChange, void *src);
 
diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 0dd986226b..f5266154f4 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -260,6 +260,10 @@ class LIBARDOUR_API Session : public PBD::StatefulDestructible, public PBD::Scop
 	bool route_name_unique (std::string) const;
 	bool route_name_internal (std::string) const;
 
+	uint32_t track_number_decimals () const {
+		return _track_number_decimals;
+	}
+
 	bool get_record_enabled() const {
 		return (record_status () >= Enabled);
 	}
@@ -1342,6 +1346,11 @@ class LIBARDOUR_API Session : public PBD::StatefulDestructible, public PBD::Scop
 	                         ChanCount input_start = ChanCount (), ChanCount output_start = ChanCount ());
 	void midi_output_change_handler (IOChange change, void* /*src*/, boost::weak_ptr<Route> midi_track);
 
+	/* track numbering */
+
+	void reassign_track_numbers ();
+	uint32_t _track_number_decimals;
+
 	/* mixer stuff */
 
 	bool solo_update_disabled;
diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index b7a8d3cf48..5df58ea846 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -102,6 +102,7 @@ Route::Route (Session& sess, string name, Flag flg, DataType default_type)
 	, _order_key (0)
 	, _has_order_key (false)
 	, _remote_control_id (0)
+	, _track_number (0)
 	, _in_configure_processors (false)
 	, _initial_io_setup (false)
 	, _custom_meter_position_noted (false)
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 2063891a72..4a3ce009eb 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -81,6 +81,7 @@
 #include "ardour/region_factory.h"
 #include "ardour/route_graph.h"
 #include "ardour/route_group.h"
+#include "ardour/route_sorters.h"
 #include "ardour/send.h"
 #include "ardour/session.h"
 #include "ardour/session_directory.h"
@@ -234,6 +235,7 @@ Session::Session (AudioEngine &eng,
 	, routes (new RouteList)
 	, _adding_routes_in_progress (false)
 	, destructive_index (0)
+	, _track_number_decimals(1)
 	, solo_update_disabled (false)
 	, default_fade_steepness (0)
 	, default_fade_msecs (0)
@@ -2349,6 +2351,8 @@ Session::add_routes (RouteList& new_routes, bool input_auto_connect, bool output
 		save_state (_current_snapshot_name);
 	}
 	
+	reassign_track_numbers();
+
 	RouteAdded (new_routes); /* EMIT SIGNAL */
 }
 
@@ -2626,6 +2630,7 @@ Session::remove_route (boost::shared_ptr<Route> route)
 	if (save_state (_current_snapshot_name)) {
 		save_history (_current_snapshot_name);
 	}
+	reassign_track_numbers();
 }
 
 void
@@ -3042,6 +3047,40 @@ Session::route_by_remote_id (uint32_t id)
 	return boost::shared_ptr<Route> ((Route*) 0);
 }
 
+
+void
+Session::reassign_track_numbers ()
+{
+	int64_t tn = 0;
+	int64_t bn = 0;
+	RouteList r (*(routes.reader ()));
+	SignalOrderRouteSorter sorter;
+	r.sort (sorter);
+
+	for (RouteList::iterator i = r.begin(); i != r.end(); ++i) {
+		if (boost::dynamic_pointer_cast<Track> (*i)) {
+			(*i)->set_track_number(++tn);
+		}
+		else if (!(*i)->is_master() && !(*i)->is_monitor() && !(*i)->is_auditioner()) {
+			(*i)->set_track_number(--bn);
+		}
+	}
+	const uint32_t decimals = ceilf (log10f (tn + 1));
+	const bool decimals_changed = _track_number_decimals != decimals;
+	_track_number_decimals = decimals;
+
+	if (decimals_changed && config.get_track_name_number ()) {
+		for (RouteList::iterator i = r.begin(); i != r.end(); ++i) {
+			boost::shared_ptr<Track> t = boost::dynamic_pointer_cast<Track> (*i);
+			if (t) {
+				t->resync_track_name();
+			}
+		}
+		// trigger GUI re-layout
+		config.ParameterChanged("track-name-number");
+	}
+}
+
 void
 Session::playlist_region_added (boost::weak_ptr<Region> w)
 {
@@ -5004,6 +5043,8 @@ Session::sync_order_keys ()
 
 	DEBUG_TRACE (DEBUG::OrderKeys, "Sync Order Keys.\n");
 
+	reassign_track_numbers();
+
 	Route::SyncOrderKeys (); /* EMIT SIGNAL */
 
 	DEBUG_TRACE (DEBUG::OrderKeys, "\tsync done\n");