Merge pull request #281 from VacuumBreather/train_speed_adaptation

# Conflicts:
#	src/saveload/extended_ver_sl.cpp
#	src/saveload/extended_ver_sl.h

src/CMakeLists.txt

@@ -479,6 +479,7 @@ add_files(
     train.h
     train_cmd.cpp
     train_gui.cpp
+    train_speed_adaptation.h
     transparency.h
     transparency_gui.cpp
     transparency_gui.h

src/date.cpp

@@ -39,6 +39,8 @@ YearMonthDay _game_load_cur_date_ymd;
 DateFract _game_load_date_fract;
 uint8 _game_load_tick_skip_counter;
 
+extern void ClearOutOfDateSignalSpeedRestrictions();
+
 /**
  * Set the date.
  * @param date  New date
@@ -283,6 +285,7 @@ static void OnNewDay()
 		SetWindowWidgetDirty(WC_STATUS_BAR, 0, WID_S_LEFT);
 	}
 	EnginesDailyLoop();
+	ClearOutOfDateSignalSpeedRestrictions();
 
 	/* Refresh after possible snowline change */
 	SetWindowClassesDirty(WC_TOWN_VIEW);

src/lang/english.txt

@@ -1818,6 +1818,8 @@ STR_CONFIG_SETTING_NOSERVICE                                    :Disable servici
 STR_CONFIG_SETTING_NOSERVICE_HELPTEXT                           :When enabled, vehicles do not get serviced if they cannot break down
 STR_CONFIG_SETTING_WAGONSPEEDLIMITS                             :Enable wagon speed limits: {STRING2}
 STR_CONFIG_SETTING_WAGONSPEEDLIMITS_HELPTEXT                    :When enabled, also use speed limits of wagons for deciding the maximum speed of a train
+STR_CONFIG_SETTING_TRAIN_SPEED_ADAPTATION                       :Enable train speed adaptation: {STRING2}
+STR_CONFIG_SETTING_TRAIN_SPEED_ADAPTATION_HELPTEXT              :When enabled, faster trains adjust their speed to match slower trains in front.
 STR_CONFIG_SETTING_SLOW_ROAD_VEHICLES_IN_CURVES                 :Road vehicles slow down in curves: {STRING2}
 STR_CONFIG_SETTING_SLOW_ROAD_VEHICLES_IN_CURVES_HELPTEXT        :When enabled, road vehicles slow down in curves. (Only with realistic acceleration)
 STR_CONFIG_SETTING_DISABLE_ELRAILS                              :Disable electric rails: {STRING2}

src/lang/german.txt

@@ -1743,6 +1743,10 @@ STR_CONFIG_SETTING_NOSERVICE                                    :Wartung deaktiv
 STR_CONFIG_SETTING_NOSERVICE_HELPTEXT                           :Schicke Fahrzeuge nicht zur Wartung, wenn Pannen ausgeschaltet sind
 STR_CONFIG_SETTING_WAGONSPEEDLIMITS                             :Berücksichtige Waggonhöchstgeschwindigkeit: {STRING}
 STR_CONFIG_SETTING_WAGONSPEEDLIMITS_HELPTEXT                    :Begrenze die Höchstgeschwindigkeit eines Zuges durch die jeweiligen Höchstgeschwindigkeiten der mitgeführten Waggons
+STR_CONFIG_SETTING_TRAIN_SPEED_ADAPTATION                       :Zuggeschwindigkeitsanpassung aktivieren: {STRING}
+STR_CONFIG_SETTING_TRAIN_SPEED_ADAPTATION_HELPTEXT              :Wenn aktiviert, passen schnellere Züge hinter langsameren Zügen ihre Geschwindigkeit an.
+STR_CONFIG_SETTING_SLOW_ROAD_VEHICLES_IN_CURVES                 :Straßenfahrzeuge werden in Kurven langsamer: {STRING}
+STR_CONFIG_SETTING_SLOW_ROAD_VEHICLES_IN_CURVES_HELPTEXT        :Wenn aktiviert, verlangsamen Straßenfahrzeuge in Kurven. (Nur im Beschleunigungsmodell „Realistisch“)
 STR_CONFIG_SETTING_DISABLE_ELRAILS                              :Deaktiviere elektrifizierte Strecken: {STRING}
 STR_CONFIG_SETTING_DISABLE_ELRAILS_HELPTEXT                     :Erlaube Elektrolokomotiven das Fahren auf nicht elektrifizierten Gleisen
 

src/misc.cpp

@@ -43,6 +43,7 @@
 
 
 extern TileIndex _cur_tileloop_tile;
+extern void ClearAllSignalSpeedRestrictions();
 extern void MakeNewgameSettingsLive();
 
 void InitializeSound();
@@ -118,6 +119,8 @@ void InitializeGame(uint size_x, uint size_y, bool reset_date, bool reset_settin
 	FreeSignalPrograms();
 	FreeSignalDependencies();
 
+	ClearAllSignalSpeedRestrictions();
+
 	ClearZoningCaches();
 	IntialiseOrderDestinationRefcountMap();
 

src/openttd.cpp

@@ -439,6 +439,9 @@ static void ShutdownGame()
 	FreeSignalPrograms();
 	FreeSignalDependencies();
 
+	extern void ClearAllSignalSpeedRestrictions();
+	ClearAllSignalSpeedRestrictions();
+
 	ClearZoningCaches();
 	ClearOrderDestinationRefcountMap();
 

src/saveload/CMakeLists.txt

@@ -48,6 +48,7 @@ add_files(
     tbtr_template_veh_sl.cpp
     town_sl.cpp
     tracerestrict_sl.cpp
+    train_speed_adaptation.cpp
     tunnel_sl.cpp
     vehicle_sl.cpp
     waypoint_sl.cpp

src/saveload/afterload.cpp

@@ -938,6 +938,10 @@ bool AfterLoadGame()
 		_settings_game.vehicle.train_braking_model = TBM_ORIGINAL;
 	}
 
+	if (SlXvIsFeatureMissing(XSLFI_TRAIN_SPEED_ADAPTATION)) {
+		_settings_game.vehicle.train_speed_adaptation = false;
+	}
+
 	AfterLoadEngines();
 
 	/* Update all vehicles */

src/saveload/extended_ver_sl.cpp

@@ -152,6 +152,7 @@ const SlxiSubChunkInfo _sl_xv_sub_chunk_infos[] = {
 	{ XSLFI_MORE_HOUSES,            XSCF_NULL,                2,   2, "more_houses",               nullptr, nullptr, nullptr        },
 	{ XSLFI_CUSTOM_TOWN_ZONE,       XSCF_IGNORABLE_UNKNOWN,   1,   1, "custom_town_zone",          nullptr, nullptr, nullptr        },
 	{ XSLFI_STATION_CARGO_HISTORY,  XSCF_NULL,                1,   1, "station_cargo_history",     nullptr, nullptr, nullptr        },
+	{ XSLFI_TRAIN_SPEED_ADAPTATION, XSCF_NULL,                1,   1, "train_speed_adaptation",    nullptr, nullptr, "TSAS"         },
 	{ XSLFI_NULL, XSCF_NULL, 0, 0, nullptr, nullptr, nullptr, nullptr },// This is the end marker
 };
 

src/saveload/extended_ver_sl.h

@@ -106,6 +106,7 @@ enum SlXvFeatureIndex {
 	XSLFI_MORE_HOUSES,                            ///< More house types
 	XSLFI_CUSTOM_TOWN_ZONE,                       ///< Custom town zones
 	XSLFI_STATION_CARGO_HISTORY,                  ///< Station waiting cargo history
+	XSLFI_TRAIN_SPEED_ADAPTATION,                 ///< Train speed adaptation
 
 	XSLFI_RIFF_HEADER_60_BIT,                     ///< Size field in RIFF chunk header is 60 bit
 	XSLFI_HEIGHT_8_BIT,                           ///< Map tile height is 8 bit instead of 4 bit, but savegame version may be before this became true in trunk

src/saveload/saveload.cpp

@@ -288,6 +288,7 @@ extern const ChunkHandler _template_replacement_chunk_handlers[];
 extern const ChunkHandler _template_vehicle_chunk_handlers[];
 extern const ChunkHandler _bridge_signal_chunk_handlers[];
 extern const ChunkHandler _tunnel_chunk_handlers[];
+extern const ChunkHandler _train_speed_adaptation_chunk_handlers[];
 extern const ChunkHandler _debug_chunk_handlers[];
 
 /** Array of all chunks in a savegame, \c nullptr terminated. */
@@ -333,6 +334,7 @@ static const ChunkHandler * const _chunk_handlers[] = {
 	_template_vehicle_chunk_handlers,
 	_bridge_signal_chunk_handlers,
 	_tunnel_chunk_handlers,
+	_train_speed_adaptation_chunk_handlers,
 	_debug_chunk_handlers,
 	nullptr,
 };

src/saveload/train_speed_adaptation.cpp

@@ -0,0 +1,51 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file train_speed_adaptation.cpp Code handling saving and loading of data for train speed adaptation */
+
+#include "../stdafx.h"
+#include "../train_speed_adaptation.h"
+#include "saveload.h"
+
+using SignalSpeedType = std::pair<const SignalSpeedKey, SignalSpeedValue>;
+
+static const SaveLoad _train_speed_adaptation_map_desc[] = {
+	SLE_VAR(SignalSpeedType, first.signal_track,           SLE_UINT8),
+	SLE_VAR(SignalSpeedType, first.last_passing_train_dir, SLE_UINT8),
+	SLE_VAR(SignalSpeedType, second.train_speed,           SLE_UINT16),
+	SLE_VAR(SignalSpeedType, second.time_stamp,            SLE_UINT64),
+	SLE_END()
+};
+
+static void Load_TSAS()
+{
+	int index;
+	SignalSpeedType data;
+	while ((index = SlIterateArray()) != -1) {
+		const_cast<SignalSpeedKey &>(data.first).signal_tile = index;
+		SlObject(&data, _train_speed_adaptation_map_desc);
+		_signal_speeds.insert(data);
+	}
+}
+
+static void RealSave_TSAS(SignalSpeedType *data)
+{
+	SlObject(data, _train_speed_adaptation_map_desc);
+}
+
+static void Save_TSAS()
+{
+	for (auto &it : _signal_speeds) {
+		SlSetArrayIndex(it.first.signal_tile);
+		SignalSpeedType *data = &it;
+		SlAutolength((AutolengthProc*) RealSave_TSAS, data);
+	}
+}
+
+extern const ChunkHandler _train_speed_adaptation_chunk_handlers[] = {
+	{ 'TSAS', Save_TSAS, Load_TSAS, nullptr, nullptr, CH_SPARSE_ARRAY | CH_LAST},
+};

src/saveload/vehicle_sl.cpp

@@ -807,6 +807,7 @@ const SaveLoad *GetVehicleDescription(VehicleType vt)
 		SLE_CONDNULL(11, SLV_2, SLV_144), // old reserved space
 		SLE_CONDVAR_X(Train, reverse_distance,    SLE_UINT16,         SL_MIN_VERSION, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_REVERSE_AT_WAYPOINT)),
 		SLE_CONDVAR_X(Train, speed_restriction,   SLE_UINT16,         SL_MIN_VERSION, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_SPEED_RESTRICTION)),
+		SLE_CONDVAR_X(Train, signal_speed_restriction, SLE_UINT16,    SL_MIN_VERSION, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_TRAIN_SPEED_ADAPTATION)),
 		SLE_CONDVAR_X(Train, critical_breakdown_count, SLE_UINT8,     SL_MIN_VERSION, SL_MAX_VERSION, SlXvFeatureTest(XSLFTO_AND, XSLFI_IMPROVED_BREAKDOWNS, 2)),
 
 		     SLE_END()

src/settings.cpp

@@ -1541,6 +1541,15 @@ static bool PublicRoadsSettingChange(int32 p1) {
 	return true;
 }
 
+static bool TrainSpeedAdaptationChanged(int32 p1) {
+	extern void ClearAllSignalSpeedRestrictions();
+	ClearAllSignalSpeedRestrictions();
+	for (Train *t : Train::Iterate()) {
+		t->signal_speed_restriction = 0;
+	}
+	return true;
+}
+
 /** Checks if any settings are set to incorrect values, and sets them to correct values in that case. */
 static void ValidateSettings()
 {
@@ -1784,7 +1793,12 @@ static bool ImprovedBreakdownsSettingChanged(int32 p1)
 
 static bool DayLengthChanged(int32 p1)
 {
+	const DateTicksScaled old_scaled_date_ticks = _scaled_date_ticks;
 	SetScaledTickVariables();
+
+	extern void AdjustAllSignalSpeedRestrictionTickValues(DateTicksScaled delta);
+	AdjustAllSignalSpeedRestrictionTickValues(_scaled_date_ticks - old_scaled_date_ticks);
+
 	MarkWholeScreenDirty();
 	return true;
 }

src/settings_gui.cpp

@@ -1924,6 +1924,7 @@ static SettingsContainer &GetSettingsTree()
 				physics->Add(new SettingEntry("vehicle.train_braking_model"));
 				physics->Add(new SettingEntry("vehicle.train_slope_steepness"));
 				physics->Add(new SettingEntry("vehicle.wagon_speed_limits"));
+				physics->Add(new SettingEntry("vehicle.train_speed_adaptation"));
 				physics->Add(new SettingEntry("vehicle.freight_trains"));
 				physics->Add(new SettingEntry("vehicle.roadveh_acceleration_model"));
 				physics->Add(new SettingEntry("vehicle.roadveh_slope_steepness"));

src/settings_type.h

@@ -573,6 +573,7 @@ struct VehicleSettings {
 	uint8  train_slope_steepness;            ///< Steepness of hills for trains when using realistic acceleration
 	uint8  roadveh_slope_steepness;          ///< Steepness of hills for road vehicles when using realistic acceleration
 	bool   wagon_speed_limits;               ///< enable wagon speed limits
+	bool   train_speed_adaptation;           ///< Faster trains slow down when behind slower trains
 	bool   slow_road_vehicles_in_curves;     ///< Road vehicles slow down in curves.
 	bool   disable_elrails;                  ///< when true, the elrails are disabled
 	UnitID max_trains;                       ///< max trains in game per company

src/table/newgrf_debug_data.h

@@ -162,8 +162,11 @@ class NIHVehicle : public NIHelper {
 			seprintf(buffer, lastof(buffer), "  T cache: veh weight: %u, user data: %u, curve speed: %u",
 					t->tcache.cached_veh_weight, t->tcache.user_def_data, t->tcache.cached_max_curve_speed);
 			print(buffer);
-			seprintf(buffer, lastof(buffer), "  Wait counter: %u, rev distance: %u, TBSN: %u, speed restriction: %u",
-					t->wait_counter, t->reverse_distance, t->tunnel_bridge_signal_num, t->speed_restriction);
+			seprintf(buffer, lastof(buffer), "  Wait counter: %u, rev distance: %u, TBSN: %u",
+					t->wait_counter, t->reverse_distance, t->tunnel_bridge_signal_num);
+			print(buffer);
+			seprintf(buffer, lastof(buffer), "  Speed restriction: %u, signal speed restriction (ATC): %u",
+					t->speed_restriction, t->signal_speed_restriction);
 			print(buffer);
 			seprintf(buffer, lastof(buffer), "  Railtype: %u, compatible_railtypes: 0x" OTTD_PRINTFHEX64,
 					t->railtype, t->compatible_railtypes);

src/table/settings.ini

@@ -64,6 +64,7 @@ static bool ClimateThresholdModeChanged(int32 p1);
 static bool VelocityUnitsChanged(int32 p1);
 static bool ChangeTrackTypeSortMode(int32 p1);
 static bool PublicRoadsSettingChange(int32 p1);
+static bool TrainSpeedAdaptationChanged(int32 p1);
 
 static bool UpdateClientName(int32 p1);
 static bool UpdateServerPassword(int32 p1);
@@ -1675,10 +1676,19 @@ strhelp  = STR_CONFIG_SETTING_SLOW_ROAD_VEHICLES_IN_CURVES_HELPTEXT
 cat      = SC_BASIC
 patxname = ""slow_road_vehicles_in_curves.vehicle.slow_road_vehicles_in_curves""
 
-;; vehicle.train_speed_adaption
-[SDT_NULL]
-length   = 1
+[SDT_XREF]
 extver   = SlXvFeatureTest(XSLFTO_AND, XSLFI_JOKERPP)
+xref     = ""vehicle.train_speed_adaptation""
+
+[SDT_BOOL]
+base     = GameSettings
+var      = vehicle.train_speed_adaptation
+def      = false
+str      = STR_CONFIG_SETTING_TRAIN_SPEED_ADAPTATION
+strhelp  = STR_CONFIG_SETTING_TRAIN_SPEED_ADAPTATION_HELPTEXT
+cat      = SC_EXPERT
+proc     = TrainSpeedAdaptationChanged
+patxname = ""train_speed_adaptation.vehicle.train_speed_adaptation""
 
 [SDT_BOOL]
 base     = GameSettings

src/train.h

@@ -147,6 +147,7 @@ struct Train FINAL : public GroundVehicle<Train, VEH_TRAIN> {
 	uint16 reverse_distance;
 	uint16 tunnel_bridge_signal_num;
 	uint16 speed_restriction;
+	uint16 signal_speed_restriction;
 
 	/** We don't want GCC to zero our struct! It already is zeroed and has an index! */
 	Train() : GroundVehicleBase() {}

src/train_cmd.cpp

@@ -44,6 +44,7 @@
 #include "scope.h"
 #include "core/checksum_func.hpp"
 #include "debug_settings.h"
+#include "train_speed_adaptation.h"
 
 #include "table/strings.h"
 #include "table/train_cmd.h"
@@ -76,6 +77,8 @@ enum ChooseTrainTrackFlags {
 };
 DECLARE_ENUM_AS_BIT_SET(ChooseTrainTrackFlags)
 
+std::unordered_map<SignalSpeedKey, SignalSpeedValue, SignalSpeedKeyHashFunc> _signal_speeds(1 << 16);
+
 static void TryLongReserveChooseTrainTrackFromReservationEnd(Train *v, bool no_reserve_vehicle_tile = false);
 static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir, TrackBits tracks, ChooseTrainTrackFlags flags, bool *p_got_reservation, ChooseTrainTrackLookAheadState lookahead_state = {});
 static bool TrainApproachingLineEnd(Train *v, bool signal, bool reverse);
@@ -92,6 +95,52 @@ static void TrainEnterStation(Train *v, StationID station);
 static void UnreserveBridgeTunnelTile(TileIndex tile);
 static bool CheckTrainStayInWormHolePathReserve(Train *t, TileIndex tile);
 
+/** Return the scaled date ticks by which the speed restriction
+ *  at the current position of the train is going to be invalid */
+static DateTicksScaled GetSpeedRestrictionTimeout(const Train *t)
+{
+	const int64 velocity = std::max<int64>(25, t->cur_speed);
+	const int64 look_ahead_distance = Clamp(t->cur_speed / 8, 6, 16); // In tiles, varying between 6 and 16 depending on current speed
+
+	// This assumes travel along the X or Y map axis, not diagonally. See GetAdvanceDistance, GetAdvanceSpeed.
+	const int64 ticks_per_tile = (192 * 16 * 4 / 3) / velocity;
+
+	const int64 ticks = ticks_per_tile * look_ahead_distance;
+
+	return _scaled_date_ticks + ticks;
+}
+
+/** Checks if the timeout of the specified signal speed restriction value has passed */
+static bool IsOutOfDate(const SignalSpeedValue& value)
+{
+	return _scaled_date_ticks > value.time_stamp;
+}
+
+/** Removes all speed restrictions from all signals */
+void ClearAllSignalSpeedRestrictions()
+{
+	_signal_speeds.clear();
+}
+
+void AdjustAllSignalSpeedRestrictionTickValues(DateTicksScaled delta)
+{
+	for (auto &it : _signal_speeds) {
+		it.second.time_stamp += delta;
+	}
+}
+
+/** Removes all speed restrictions which have passed their timeout from all signals */
+void ClearOutOfDateSignalSpeedRestrictions()
+{
+	for(auto key_value_pair = _signal_speeds.begin(); key_value_pair != _signal_speeds.end(); ) {
+		if (IsOutOfDate(key_value_pair->second)) {
+			key_value_pair = _signal_speeds.erase(key_value_pair);
+		} else {
+			++key_value_pair;
+		}
+	}
+}
+
 inline void ClearLookAheadIfInvalid(Train *v)
 {
 	if (v->lookahead != nullptr && !ValidateLookAhead(v)) v->lookahead.reset();
@@ -1024,6 +1073,9 @@ Train::MaxSpeedInfo Train::GetCurrentMaxSpeedInfoInternal(bool update_state) con
 	if (this->speed_restriction != 0) {
 		advisory_max_speed = std::min<int>(advisory_max_speed, this->speed_restriction);
 	}
+	if (this->signal_speed_restriction != 0 && _settings_game.vehicle.train_speed_adaptation) {
+		advisory_max_speed = std::min<int>(advisory_max_speed, this->signal_speed_restriction);
+	}
 	if (this->reverse_distance > 1) {
 		advisory_max_speed = std::min<int>(advisory_max_speed, ReversingDistanceTargetSpeed(this));
 	}
@@ -1328,6 +1380,7 @@ static CommandCost CmdBuildRailWagon(TileIndex tile, DoCommandFlag flags, const
 		v->vehstatus = VS_HIDDEN | VS_DEFPAL;
 		v->reverse_distance = 0;
 		v->speed_restriction = 0;
+		v->signal_speed_restriction = 0;
 
 		v->SetWagon();
 
@@ -4444,6 +4497,7 @@ static void TrainEnterStation(Train *v, StationID station)
 		v->current_order.MakeWaiting();
 		v->current_order.SetNonStopType(ONSF_NO_STOP_AT_ANY_STATION);
 		v->cur_speed = 0;
+		v->signal_speed_restriction = 0;
 		return;
 	}
 
@@ -5500,7 +5554,33 @@ bool TrainController(Train *v, Vehicle *nomove, bool reverse)
 		}
 
 		if (update_signals_crossing) {
+
 			if (v->IsFrontEngine()) {
+				if (_settings_game.vehicle.train_speed_adaptation && IsTileType(gp.old_tile, MP_RAILWAY) && HasSignals(gp.old_tile)) {
+					const TrackdirBits rev_tracks = TrackBitsToTrackdirBits(GetTrackBits(gp.old_tile)) & DiagdirReachesTrackdirs(ReverseDiagDir(enterdir));
+					const Trackdir rev_trackdir = FindFirstTrackdir(rev_tracks);
+					if (HasSignalOnTrackdir(gp.old_tile, ReverseTrackdir(rev_trackdir))) {
+						const Track track = TrackdirToTrack(rev_trackdir);
+						SignalSpeedKey speed_key = {
+							speed_key.signal_tile = gp.old_tile,
+							speed_key.signal_track = track,
+							speed_key.last_passing_train_dir = v->GetVehicleTrackdir()
+						};
+						const auto found_speed_restriction = _signal_speeds.find(speed_key);
+
+						if (found_speed_restriction != _signal_speeds.end()) {
+							if (IsOutOfDate(found_speed_restriction->second)) {
+								_signal_speeds.erase(found_speed_restriction);
+								v->signal_speed_restriction = 0;
+							} else {
+								v->signal_speed_restriction = std::max<uint16>(25, found_speed_restriction->second.train_speed);
+							}
+						} else {
+							v->signal_speed_restriction = 0;
+						}
+					}
+				}
+
 				switch (TrainMovedChangeSignal(v, gp.new_tile, enterdir, true)) {
 					case CHANGED_NORMAL_TO_PBS_BLOCK:
 						/* We are entering a block with PBS signals right now, but
@@ -5538,17 +5618,33 @@ bool TrainController(Train *v, Vehicle *nomove, bool reverse)
 				TrainMovedChangeSignal(v, gp.old_tile, ReverseDiagDir(enterdir), false);
 				if (IsLevelCrossingTile(gp.old_tile)) UpdateLevelCrossing(gp.old_tile);
 
-				if (IsTileType(gp.old_tile, MP_RAILWAY) && HasSignals(gp.old_tile) && IsRestrictedSignal(gp.old_tile)) {
+				if (IsTileType(gp.old_tile, MP_RAILWAY) && HasSignals(gp.old_tile)) {
 					const TrackdirBits rev_tracks = TrackBitsToTrackdirBits(GetTrackBits(gp.old_tile)) & DiagdirReachesTrackdirs(ReverseDiagDir(enterdir));
 					const Trackdir rev_trackdir = FindFirstTrackdir(rev_tracks);
 					const Track track = TrackdirToTrack(rev_trackdir);
+
+					if (_settings_game.vehicle.train_speed_adaptation && HasSignalOnTrackdir(gp.old_tile, ReverseTrackdir(rev_trackdir))) {
+						SignalSpeedKey speed_key = {
+							speed_key.signal_tile = gp.old_tile,
+							speed_key.signal_track = track,
+							speed_key.last_passing_train_dir = v->GetVehicleTrackdir()
+						};
+						SignalSpeedValue speed_value = {
+							speed_value.train_speed = v->First()->cur_speed,
+							speed_value.time_stamp = GetSpeedRestrictionTimeout(v->First())
+						};
+						_signal_speeds[speed_key] = speed_value;
+					}
+
 					if (HasSignalOnTrack(gp.old_tile, track)) {
-						const TraceRestrictProgram *prog = GetExistingTraceRestrictProgram(gp.old_tile, track);
-						if (prog && prog->actions_used_flags & TRPAUF_SLOT_RELEASE_BACK) {
-							TraceRestrictProgramResult out;
-							TraceRestrictProgramInput input(gp.old_tile, ReverseTrackdir(rev_trackdir), nullptr, nullptr);
-							input.permitted_slot_operations = TRPISP_RELEASE_BACK;
-							prog->Execute(first, input, out);
+						if (IsRestrictedSignal(gp.old_tile)) {
+							const TraceRestrictProgram *prog = GetExistingTraceRestrictProgram(gp.old_tile, track);
+							if (prog && prog->actions_used_flags & TRPAUF_SLOT_RELEASE_BACK) {
+								TraceRestrictProgramResult out;
+								TraceRestrictProgramInput input(gp.old_tile, ReverseTrackdir(rev_trackdir), nullptr, nullptr);
+								input.permitted_slot_operations = TRPISP_RELEASE_BACK;
+								prog->Execute(first, input, out);
+							}
 						}
 					}
 				}

src/train_speed_adaptation.h

@@ -0,0 +1,53 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file train_speed_adaptation.h Train speed adaptation data structures. */
+
+#ifndef TRAIN_SPEED_ADAPTATION_H
+#define TRAIN_SPEED_ADAPTATION_H
+
+#include "date_type.h"
+#include "track_type.h"
+#include "tile_type.h"
+
+#include <unordered_map>
+
+struct SignalSpeedKey
+{
+	TileIndex signal_tile;
+	Track signal_track;
+	Trackdir last_passing_train_dir;
+
+	bool operator==(const SignalSpeedKey& other) const
+	{
+		return signal_tile == other.signal_tile &&
+			signal_track == other.signal_track &&
+			last_passing_train_dir == other.last_passing_train_dir;
+	}
+};
+
+struct SignalSpeedValue
+{
+	uint16 train_speed;
+	DateTicksScaled time_stamp;
+};
+
+struct SignalSpeedKeyHashFunc
+{
+	std::size_t operator() (const SignalSpeedKey &key) const
+	{
+		const std::size_t h1 = std::hash<TileIndex>()(key.signal_tile);
+		const std::size_t h2 = std::hash<Trackdir>()(key.last_passing_train_dir);
+		const std::size_t h3 = std::hash<Track>()(key.signal_track);
+
+		return (h1 ^ h2) ^ h3;
+	}
+};
+
+extern std::unordered_map<SignalSpeedKey, SignalSpeedValue, SignalSpeedKeyHashFunc> _signal_speeds;
+
+#endif /* TRAIN_SPEED_ADAPTATION_H */

src/vehicle.cpp

@@ -2417,6 +2417,7 @@ void VehicleEnterDepot(Vehicle *v)
 			ClrBit(t->flags, VRF_TOGGLE_REVERSE);
 			t->ConsistChanged(CCF_ARRANGE);
 			t->reverse_distance = 0;
+			t->signal_speed_restriction = 0;
 			t->lookahead.reset();
 			if (!(t->vehstatus & VS_CRASHED)) {
 				t->crash_anim_pos = 0;
@@ -4309,4 +4310,7 @@ void ShiftVehicleDates(int interval)
 	for (Vehicle *v : Vehicle::Iterate()) {
 		v->date_of_last_service += interval;
 	}
+
+	extern void AdjustAllSignalSpeedRestrictionTickValues(DateTicksScaled delta);
+	AdjustAllSignalSpeedRestrictionTickValues(interval * DAY_TICKS * _settings_game.economy.day_length_factor);
 }