Add wallclock time settings

src/cheat_gui.cpp

@@ -113,7 +113,7 @@ static int32_t ClickChangeDateCheat(int32_t p1, int32_t p2)
 	/* Change the date. */
 	CalTime::Detail::SetDate(new_date, CalTime::CurDateFract());
 
-	{
+	if (!EconTime::UsingWallclockUnits()) {
 		EconTime::Date new_econ_date = new_date.base();
 		EconTime::DateFract new_econ_date_fract = CalTime::CurDateFract();
 

src/date.cpp

@@ -246,21 +246,37 @@ CalTime::Date CalTime::ConvertYMDToDate(CalTime::Year year, CalTime::Month month
 
 EconTime::YearMonthDay EconTime::ConvertDateToYMD(EconTime::Date date)
 {
-	/* Process the same as calendar time (for now) */
+	if (EconTime::UsingWallclockUnits()) {
+		/* If we're using wallclock units, economy months have 30 days and an economy year has 360 days. */
+		EconTime::YearMonthDay ymd;
+		ymd.year =date.base() / EconTime::DAYS_IN_ECONOMY_WALLCLOCK_YEAR;
+		ymd.month = (date.base() % EconTime::DAYS_IN_ECONOMY_WALLCLOCK_YEAR) / EconTime::DAYS_IN_ECONOMY_WALLCLOCK_MONTH;
+		ymd.day = date.base() % EconTime::DAYS_IN_ECONOMY_WALLCLOCK_MONTH;
+		return ymd;
+	}
+
+	/* Process the same as calendar time */
 	CalTime::YearMonthDay ymd = CalTime::ConvertDateToYMD(date.base());
 	return { ymd.year.base(), ymd.month, ymd.day };
 }
 
 EconTime::Date EconTime::ConvertYMDToDate(EconTime::Year year, EconTime::Month month, EconTime::Day day)
 {
-	/* Process the same as calendar time (for now) */
+	if (EconTime::UsingWallclockUnits()) {
+		/* If we're using wallclock units, economy months have 30 days and an economy year has 360 days. */
+		const int total_months = (year.base() * MONTHS_IN_YEAR) + month;
+		return (total_months * EconTime::DAYS_IN_ECONOMY_WALLCLOCK_MONTH) + day - 1; // Day is 1-indexed but Date is 0-indexed, hence the - 1.
+	}
+
+	/* Process the same as calendar time */
 	return CalTime::ConvertYMDToDate(year.base(), month, day).base();
 }
 
 bool EconTime::UsingWallclockUnits(bool newgame)
 {
-	/* Always return false (for now) */
-	return false;
+	if (newgame) return (_settings_newgame.economy.timekeeping_units == TKU_WALLCLOCK);
+
+	return (_settings_game.economy.timekeeping_units == TKU_WALLCLOCK);
 }
 
 /** Functions used by the IncreaseDate function */
@@ -397,6 +413,18 @@ static void OnNewEconomyDay()
 
 static void IncreaseCalendarDate()
 {
+	/* If calendar day progress is frozen, don't try to advance time. */
+	if (_settings_game.economy.minutes_per_calendar_year == CalTime::FROZEN_MINUTES_PER_YEAR) return;
+
+	/* If we are using a non-default calendar progression speed, we need to check the sub_date_fract before updating date_fract. */
+	if (_settings_game.economy.minutes_per_calendar_year != CalTime::DEF_MINUTES_PER_YEAR) {
+		CalTime::Detail::now.sub_date_fract++;
+
+		/* Check if we are ready to increment date_fract */
+		if (CalTime::Detail::now.sub_date_fract < (DAY_TICKS * _settings_game.economy.minutes_per_calendar_year) / CalTime::DEF_MINUTES_PER_YEAR) return;
+	}
+	CalTime::Detail::now.sub_date_fract = 0;
+
 	CalTime::Detail::now.cal_date_fract++;
 	if (CalTime::Detail::now.cal_date_fract < DAY_TICKS) return;
 	CalTime::Detail::now.cal_date_fract = 0;

src/date_gui.cpp

@@ -124,7 +124,7 @@ struct SetDateWindow : Window {
 				break;
 
 			case WID_SD_YEAR:
-				SetDParamMaxValue(0, this->max_year.base());
+				SetDParamMaxValue(0, this->max_year);
 				d = maxdim(d, GetStringBoundingBox(STR_JUST_INT));
 				break;
 		}

src/date_type.h

@@ -176,6 +176,10 @@ struct CalTime : public DateDetail::BaseTime<struct CalendarTimeTag> {
 		static State NewState(Year year);
 	};
 
+	static constexpr int DEF_MINUTES_PER_YEAR = 12;
+	static constexpr int FROZEN_MINUTES_PER_YEAR = 0;
+	static constexpr int MAX_MINUTES_PER_YEAR = 10080; // One week of real time. The actual max that doesn't overflow TimerGameCalendar::sub_date_fract is 10627, but this is neater.
+
 	static inline const YearMonthDay &CurYMD()             { return Detail::now.cal_ymd; }
 	static inline Year                CurYear()            { return Detail::now.cal_ymd.year; }
 	static inline Month               CurMonth()           { return Detail::now.cal_ymd.month; }
@@ -213,20 +217,42 @@ struct CalTime : public DateDetail::BaseTime<struct CalendarTimeTag> {
 };
 
 struct EconTime : public DateDetail::BaseTime<struct EconTimeTag> {
+	using ParentBaseTime = DateDetail::BaseTime<struct EconTimeTag>;
+
 	/* Use a state struct to make backup/restore/init simpler */
 	struct State {
 		YearMonthDay econ_ymd;
 		Date         econ_date;
 		DateFract    econ_date_fract;
 	};
+
+	static constexpr int DAYS_IN_ECONOMY_WALLCLOCK_YEAR = 360; ///< Days in an economy year, when in wallclock timekeeping mode.
+	static constexpr int DAYS_IN_ECONOMY_WALLCLOCK_MONTH = 30; ///< Days in an economy month, when in wallclock timekeeping mode.
+
 	/* Use a detail struct/namespace to more easily control writes */
 	struct Detail {
 		static State now;
 
 		static void SetDate(Date date, DateFract fract);
 		static State NewState(Year year);
+
+		/**
+		 * Calculate the date of the first day of a given year.
+		 * @param year the year to get the first day of.
+		 * @return the date (when using wallclock 30-day months).
+		 */
+		static constexpr Date DateAtStartOfWallclockModeYear(Year year)
+		{
+			return DAYS_IN_ECONOMY_WALLCLOCK_YEAR * year.base();
+		}
 	};
 
+	/**
+	 * The offset in days from the '_date == 0' till
+	 * 'ConvertYMDToDate(ORIGINAL_BASE_YEAR, 0, 1)', when using wallclock 30-day months
+	 */
+	static constexpr Date DAYS_TILL_ORIGINAL_BASE_YEAR_WALLCLOCK_MODE = DAYS_IN_ECONOMY_WALLCLOCK_YEAR * ORIGINAL_BASE_YEAR.base();
+
 	static inline const YearMonthDay &CurYMD()             { return Detail::now.econ_ymd; }
 	static inline Year                CurYear()            { return Detail::now.econ_ymd.year; }
 	static inline Month               CurMonth()           { return Detail::now.econ_ymd.month; }
@@ -244,6 +270,17 @@ struct EconTime : public DateDetail::BaseTime<struct EconTimeTag> {
 	}
 
 	static bool UsingWallclockUnits(bool newgame = false);
+
+	/**
+	 * Calculate the date of the first day of a given year.
+	 * @param year the year to get the first day of.
+	 * @return the date.
+	 */
+	static inline Date DateAtStartOfYear(Year year)
+	{
+		if (UsingWallclockUnits()) return Detail::DateAtStartOfWallclockModeYear(year);
+		return ParentBaseTime::Detail::DateAtStartOfCalendarYear(year);
+	}
 };
 
 namespace DateDetail {

src/misc.cpp

@@ -158,7 +158,9 @@ void InitializeGame(uint size_x, uint size_y, bool reset_date, bool reset_settin
 
 	if (reset_date) {
 		CalTime::Detail::SetDate(CalTime::ConvertYMDToDate(_settings_game.game_creation.starting_year, 0, 1), 0);
-		{
+		if (EconTime::UsingWallclockUnits()) {
+			EconTime::Detail::SetDate(EconTime::DAYS_TILL_ORIGINAL_BASE_YEAR_WALLCLOCK_MODE, 0);
+		} else {
 			EconTime::Detail::SetDate(CalTime::CurDate().base(), 0);
 		}
 		InitializeOldNames();

src/newgrf_industries.cpp

@@ -431,6 +431,7 @@ uint32_t IndustriesScopeResolver::GetCountAndDistanceOfClosestInstance(byte para
 		case 0xB3: return this->industry->construction_type; // Construction type
 		case 0xB4: {
 			EconTime::Date *latest = std::max_element(this->industry->last_cargo_accepted_at, endof(this->industry->last_cargo_accepted_at));
+			if (EconTime::UsingWallclockUnits()) return ClampTo<uint16_t>((*latest) - EconTime::DAYS_TILL_ORIGINAL_BASE_YEAR_WALLCLOCK_MODE);
 			return ClampTo<uint16_t>((*latest) - EconTime::DAYS_TILL_ORIGINAL_BASE_YEAR); // Date last cargo accepted since 1920 (in days)
 		}
 	}

src/order_cmd.cpp

@@ -2962,13 +2962,21 @@ void DeleteVehicleOrders(Vehicle *v, bool keep_orderlist, bool reset_order_indic
 
 /**
  * Clamp the service interval to the correct min/max. The actual min/max values
- * depend on whether it's in percent or days.
- * @param interval proposed service interval
- * @return Clamped service interval
+ * depend on whether it's in days, minutes, or percent.
+ * @param interval The proposed service interval.
+ * @param ispercent Whether the interval is a percent.
+ * @return The service interval clamped to use the chosen units.
  */
 uint16_t GetServiceIntervalClamped(int interval, bool ispercent)
 {
-	return ispercent ? Clamp(interval, MIN_SERVINT_PERCENT, MAX_SERVINT_PERCENT) : Clamp(interval, MIN_SERVINT_DAYS, MAX_SERVINT_DAYS);
+	/* Service intervals are in percents. */
+	if (ispercent) return Clamp(interval, MIN_SERVINT_PERCENT, MAX_SERVINT_PERCENT);
+
+	/* Service intervals are in minutes. */
+	if (EconTime::UsingWallclockUnits(_game_mode == GM_MENU)) return Clamp(interval, MIN_SERVINT_MINUTES, MAX_SERVINT_MINUTES);
+
+	/* Service intervals are in days. */
+	return Clamp(interval, MIN_SERVINT_DAYS, MAX_SERVINT_DAYS);
 }
 
 /**

src/order_func.h

@@ -42,6 +42,13 @@ static const uint DEF_SERVINT_DAYS_SHIPS    = 360;
 static const uint MIN_SERVINT_DAYS          = 30;
 static const uint MAX_SERVINT_DAYS          = 800;
 
+static const uint DEF_SERVINT_MINUTES_TRAINS   = 5;
+static const uint DEF_SERVINT_MINUTES_ROADVEH  = 5;
+static const uint DEF_SERVINT_MINUTES_AIRCRAFT = 3;
+static const uint DEF_SERVINT_MINUTES_SHIPS    = 12;
+static const uint MIN_SERVINT_MINUTES          = 1;
+static const uint MAX_SERVINT_MINUTES          = 30;
+
 static const uint DEF_SERVINT_PERCENT = 50;
 static const uint MIN_SERVINT_PERCENT = 5;
 static const uint MAX_SERVINT_PERCENT = 90;

src/saveload/afterload.cpp

@@ -873,6 +873,11 @@ bool AfterLoadGame()
 	 * must be done before loading sprites as some newgrfs check it */
 	CalTime::Detail::SetDate(CalTime::CurDate(), CalTime::CurDateFract());
 
+	/* Only new games can use wallclock units. */
+	if (SlXvIsFeatureMissing(XSLFI_VARIABLE_DAY_LENGTH, 5) && IsSavegameVersionBefore(SLV_ECONOMY_MODE_TIMEKEEPING_UNITS)) {
+		_settings_game.economy.timekeeping_units = TKU_CALENDAR;
+	}
+
 	if (SlXvIsFeaturePresent(XSLFI_VARIABLE_DAY_LENGTH, 5) || !IsSavegameVersionBefore(SLV_ECONOMY_DATE)) {
 		EconTime::Detail::SetDate(EconTime::CurDate(), EconTime::CurDateFract());
 	} else {

src/settings.cpp

@@ -1079,6 +1079,12 @@ static void UpdateAllServiceInterval(int32_t new_value)
 		vds->servint_roadveh  = DEF_SERVINT_PERCENT;
 		vds->servint_aircraft = DEF_SERVINT_PERCENT;
 		vds->servint_ships    = DEF_SERVINT_PERCENT;
+	} else if (EconTime::UsingWallclockUnits(_game_mode == GM_MENU)) {
+		/* Service intervals are in minutes. */
+		vds->servint_trains   = DEF_SERVINT_MINUTES_TRAINS;
+		vds->servint_roadveh  = DEF_SERVINT_MINUTES_ROADVEH;
+		vds->servint_aircraft = DEF_SERVINT_MINUTES_AIRCRAFT;
+		vds->servint_ships    = DEF_SERVINT_MINUTES_SHIPS;
 	} else {
 		/* Service intervals are in days. */
 		vds->servint_trains   = DEF_SERVINT_DAYS_TRAINS;
@@ -1127,6 +1133,85 @@ static void UpdateServiceInterval(VehicleType type, int32_t new_value)
 	SetWindowClassesDirty(WC_VEHICLE_DETAILS);
 }
 
+/**
+ * Callback for when the player changes the timekeeping units.
+ * @param Unused.
+ */
+static void ChangeTimekeepingUnits(int32_t)
+{
+	/* If service intervals are in time units (calendar days or real-world minutes), reset them to the correct defaults. */
+	if (!_settings_client.company.vehicle.servint_ispercent) {
+		UpdateAllServiceInterval(0);
+	}
+
+	/* If we are using calendar timekeeping, "minutes per year" must be default. */
+	if (_game_mode == GM_MENU && !EconTime::UsingWallclockUnits(true)) {
+		_settings_newgame.economy.minutes_per_calendar_year = CalTime::DEF_MINUTES_PER_YEAR;
+	}
+
+	InvalidateWindowClassesData(WC_GAME_OPTIONS, 0);
+
+	/* It is possible to change these units in Scenario Editor. We must set the economy date appropriately. */
+	if (_game_mode == GM_EDITOR) {
+		EconTime::Date new_economy_date;
+		EconTime::DateFract new_economy_date_fract;
+
+		if (EconTime::UsingWallclockUnits()) {
+			/* If the new mode is wallclock units, set the economy year back to 1. */
+			new_economy_date = EconTime::DAYS_TILL_ORIGINAL_BASE_YEAR_WALLCLOCK_MODE;
+			new_economy_date_fract = 0;
+		} else {
+			/* If the new mode is calendar units, sync the economy year with the calendar year. */
+			new_economy_date = CalTime::CurDate().base();
+			new_economy_date_fract = CalTime::CurDateFract();
+		}
+
+		/* If you open a savegame as a scenario, there may already be link graphs and/or vehicles. These use economy date. */
+		LinkGraphSchedule::instance.ShiftDates(new_economy_date - EconTime::CurDate());
+		ShiftVehicleDates(new_economy_date - EconTime::CurDate());
+
+		/* Only change the date after changing cached values above. */
+		EconTime::Detail::SetDate(new_economy_date, new_economy_date_fract);
+		UpdateOrderUIOnDateChange();
+	}
+
+	UpdateEffectiveDayLengthFactor();
+}
+
+/**
+ * Callback after the player changes the minutes per year.
+ * @param new_value The intended new value of the setting, used for clamping.
+ */
+static void ChangeMinutesPerYear(int32_t new_value)
+{
+	/* We don't allow setting Minutes Per Year below default, unless it's to 0 for frozen calendar time. */
+	if (new_value < CalTime::DEF_MINUTES_PER_YEAR) {
+		int clamped;
+
+		/* If the new value is 1, we're probably at 0 and trying to increase the value, so we should jump up to default. */
+		if (new_value == 1) {
+			clamped = CalTime::DEF_MINUTES_PER_YEAR;
+		} else {
+			clamped = CalTime::FROZEN_MINUTES_PER_YEAR;
+		}
+
+		/* Override the setting with the clamped value. */
+		if (_game_mode == GM_MENU) {
+			_settings_newgame.economy.minutes_per_calendar_year = clamped;
+		} else {
+			_settings_game.economy.minutes_per_calendar_year = clamped;
+		}
+	}
+
+	/* If the setting value is not the default, force the game to use wallclock timekeeping units.
+	 * This can only happen in the menu, since the pre_cb ensures this setting can only be changed there, or if we're already using wallclock units.
+	 */
+	if (_game_mode == GM_MENU && (_settings_newgame.economy.minutes_per_calendar_year != CalTime::DEF_MINUTES_PER_YEAR)) {
+		_settings_newgame.economy.timekeeping_units = TKU_WALLCLOCK;
+		InvalidateWindowClassesData(WC_GAME_OPTIONS, 0);
+	}
+}
+
 static void TrainAccelerationModelChanged(int32_t new_value)
 {
 	for (Train *t : Train::Iterate()) {

src/settings_gui.cpp

@@ -2432,6 +2432,8 @@ static SettingsContainer &GetSettingsTree()
 		{
 			SettingsPage *time = environment->Add(new SettingsPage(STR_CONFIG_SETTING_ENVIRONMENT_TIME));
 			{
+				time->Add(new SettingEntry("economy.timekeeping_units"));
+				time->Add(new SettingEntry("economy.minutes_per_calendar_year"));
 				time->Add(new SettingEntry("game_creation.ending_year"));
 				time->Add(new SettingEntry("gui.pause_on_newgame"));
 				time->Add(new SettingEntry("gui.fast_forward_speed_limit"));

src/settings_type.h

@@ -64,6 +64,12 @@ enum IndustryDensity {
 	ID_END,       ///< Number of industry density settings.
 };
 
+/** Possible values for the "timekeeping_units" setting. */
+enum TimekeepingUnits : uint8_t {
+	TKU_CALENDAR = 0,
+	TKU_WALLCLOCK,
+};
+
 /** Possible values for "use_relay_service" setting. */
 enum UseRelayService : uint8_t {
 	URS_NEVER = 0,
@@ -763,6 +769,8 @@ struct EconomySettings {
 	uint8_t  town_max_road_slope;            ///< maximum number of consecutive sloped road tiles which towns are allowed to build
 	bool   allow_town_bridges;               ///< towns are allowed to build bridges
 	bool   infrastructure_maintenance;       ///< enable monthly maintenance fee for owner infrastructure
+	TimekeepingUnits timekeeping_units;      ///< time units to use for the game economy, either calendar or wallclock
+	uint16_t minutes_per_calendar_year;      ///< minutes per calendar year. Special value 0 means that calendar time is frozen.
 	uint16_t town_cargo_scale;               ///< scale cargo production of towns by this percentage.
 	uint16_t industry_cargo_scale;           ///< scale cargo production of industries by this percentage.
 	CargoScalingMode town_cargo_scale_mode;  ///< scaling mode for town cargo.
@@ -890,7 +898,7 @@ struct GameSettings {
 
 	uint8_t EffectiveDayLengthFactor() const
 	{
-		return this->economy.day_length_factor;
+		return this->economy.timekeeping_units == TKU_CALENDAR ? this->economy.day_length_factor : 1;
 	}
 };
 

src/subsidy_gui.cpp

@@ -157,7 +157,15 @@ struct SubsidyListWindow : Window {
 				if (IsInsideMM(pos, 0, cap)) {
 					/* Displays the two offered towns */
 					SetupSubsidyDecodeParam(s, SubsidyDecodeParamType::Gui);
-					SetDParam(7, EconTime::CurDate() - EconTime::CurDay() + s->remaining * 32);
+					/* If using wallclock units, show minutes remaining. Otherwise show the date when the subsidy ends. */
+					if (EconTime::UsingWallclockUnits()) {
+						SetDParam(7, STR_SUBSIDIES_OFFERED_EXPIRY_TIME);
+						SetDParam(8, s->remaining + 1); // We get the rest of the current economy month for free, since the expiration is checked on each new month.
+					} else {
+						SetDParam(7, STR_SUBSIDIES_OFFERED_EXPIRY_DATE);
+						SetDParam(8, EconTime::CurDate() - EconTime::CurDay() + s->remaining * 32);
+					}
+
 					DrawString(tr.left, tr.right, tr.top + pos * GetCharacterHeight(FS_NORMAL), STR_SUBSIDIES_OFFERED_FROM_TO);
 				}
 				pos++;
@@ -181,7 +189,15 @@ struct SubsidyListWindow : Window {
 				if (IsInsideMM(pos, 0, cap)) {
 					SetupSubsidyDecodeParam(s, SubsidyDecodeParamType::Gui);
 					SetDParam(7, s->awarded);
-					SetDParam(8, EconTime::CurDate() - EconTime::CurDay() + s->remaining * 32);
+					/* If using wallclock units, show minutes remaining. Otherwise show the date when the subsidy ends. */
+					if (EconTime::UsingWallclockUnits()) {
+						SetDParam(8, STR_SUBSIDIES_SUBSIDISED_EXPIRY_TIME);
+						SetDParam(9, s->remaining);
+					}
+					else {
+						SetDParam(8, STR_SUBSIDIES_SUBSIDISED_EXPIRY_DATE);
+						SetDParam(9, EconTime::CurDate() - EconTime::CurDay() + s->remaining * 32);
+					}
 
 					/* Displays the two connected stations */
 					DrawString(tr.left, tr.right, tr.top + pos * GetCharacterHeight(FS_NORMAL), STR_SUBSIDIES_SUBSIDISED_FROM_TO);

src/table/settings/economy_settings.ini

@@ -9,6 +9,8 @@
 
 [pre-amble]
 static void TownFoundingChanged(int32_t new_value);
+static void ChangeTimekeepingUnits(int32_t new_value);
+static void ChangeMinutesPerYear(int32_t new_value);
 static void InvalidateCompanyWindow(int32_t new_value);
 static void DayLengthChanged(int32_t new_value);
 static bool CheckSharingRail(int32_t &new_value);
@@ -702,10 +704,37 @@ strhelp  = STR_CONFIG_SETTING_INFRASTRUCTURE_MAINTENANCE_HELPTEXT
 post_cb  = [](auto) { InvalidateWindowClassesData(WC_COMPANY_INFRASTRUCTURE); }
 cat      = SC_BASIC
 
+[SDT_VAR]
+var      = economy.timekeeping_units
+type     = SLE_UINT8
+flags    = SF_GUI_DROPDOWN | SF_NEWGAME_ONLY | SF_SCENEDIT_TOO
+def      = TKU_CALENDAR
+min      = TKU_CALENDAR
+max      = TKU_WALLCLOCK
+str      = STR_CONFIG_SETTING_TIMEKEEPING_UNITS
+strval   = STR_CONFIG_SETTING_TIMEKEEPING_UNITS_CALENDAR
+strhelp  = STR_CONFIG_SETTING_TIMEKEEPING_UNITS_HELPTEXT
+post_cb  = ChangeTimekeepingUnits
+cat      = SC_BASIC
+
+[SDT_VAR]
+var      = economy.minutes_per_calendar_year
+type     = SLE_UINT16
+flags    = SF_GUI_0_IS_SPECIAL
+def      = CalTime::DEF_MINUTES_PER_YEAR
+min      = CalTime::FROZEN_MINUTES_PER_YEAR
+max      = CalTime::MAX_MINUTES_PER_YEAR
+interval = 1
+str      = STR_CONFIG_SETTING_MINUTES_PER_YEAR
+strhelp  = STR_CONFIG_SETTING_MINUTES_PER_YEAR_HELPTEXT
+strval   = STR_CONFIG_SETTING_MINUTES_PER_YEAR_VALUE
+pre_cb   = [](auto) { return _game_mode == GM_MENU || _settings_game.economy.timekeeping_units == 1; }
+post_cb  = ChangeMinutesPerYear
+cat      = SC_BASIC
+
 [SDT_VAR]
 var      = economy.town_cargo_scale
 type     = SLE_UINT16
-flags    = SF_PATCH
 def      = 100
 min      = 1
 max      = 5000
@@ -720,7 +749,6 @@ guiproc  = TownCargoScaleGUI
 [SDT_VAR]
 var      = economy.industry_cargo_scale
 type     = SLE_UINT16
-flags    = SF_PATCH
 def      = 100
 min      = 5
 max      = 3000

src/vehicle_gui.cpp

@@ -2819,13 +2819,20 @@ extern void DrawRoadVehDetails(const Vehicle *v, const Rect &r);
 extern void DrawShipDetails(const Vehicle *v, const Rect &r);
 extern void DrawAircraftDetails(const Aircraft *v, const Rect &r);
 
-static StringID _service_interval_dropdown[] = {
+static StringID _service_interval_dropdown_calendar[] = {
 	STR_VEHICLE_DETAILS_DEFAULT,
 	STR_VEHICLE_DETAILS_DAYS,
 	STR_VEHICLE_DETAILS_PERCENT,
 	INVALID_STRING_ID,
 };
 
+static StringID _service_interval_dropdown_wallclock[] = {
+	STR_VEHICLE_DETAILS_DEFAULT,
+	STR_VEHICLE_DETAILS_MINUTES,
+	STR_VEHICLE_DETAILS_PERCENT,
+	INVALID_STRING_ID,
+};
+
 /** Class for managing the vehicle details window. */
 struct VehicleDetailsWindow : Window {
 	TrainDetailsWindowTabs tab; ///< For train vehicles: which tab is displayed.
@@ -3024,9 +3031,10 @@ struct VehicleDetailsWindow : Window {
 
 			case WID_VD_SERVICE_INTERVAL_DROPDOWN: {
 				Dimension d{0, 0};
-				StringID *strs = _service_interval_dropdown;
-				while (*strs != INVALID_STRING_ID) {
-					d = maxdim(d, GetStringBoundingBox(*strs++));
+				for (const StringID *strs : {_service_interval_dropdown_calendar, _service_interval_dropdown_wallclock}) {
+					while (*strs != INVALID_STRING_ID) {
+						d = maxdim(d, GetStringBoundingBox(*strs++));
+					}
 				}
 				d.width += padding.width;
 				d.height += padding.height;
@@ -3036,7 +3044,17 @@ struct VehicleDetailsWindow : Window {
 
 			case WID_VD_SERVICING_INTERVAL:
 				SetDParamMaxValue(0, MAX_SERVINT_DAYS); // Roughly the maximum interval
-				SetDParamMaxValue(1, CalTime::MAX_YEAR.base() * DAYS_IN_YEAR); // Roughly the maximum year
+
+				/* Do we show the last serviced value as a date or minutes since service? */
+				if (EconTime::UsingWallclockUnits()) {
+					SetDParam(1, STR_VEHICLE_DETAILS_LAST_SERVICE_MINUTES_AGO);
+					/* Vehicle was last serviced at year 0, and we're at max year */
+					SetDParamMaxValue(2, MONTHS_IN_YEAR * EconTime::MAX_YEAR.base());
+				} else {
+					SetDParam(1, STR_VEHICLE_DETAILS_LAST_SERVICE_DATE);
+					/* Vehicle was last serviced at year 0, and we're at max year */
+					SetDParamMaxValue(2, EconTime::DateAtStartOfYear(EconTime::MAX_YEAR));
+				}
 				size->width = std::max(
 					GetStringBoundingBox(STR_VEHICLE_DETAILS_SERVICING_INTERVAL_PERCENT).width,
 					GetStringBoundingBox(STR_VEHICLE_DETAILS_SERVICING_INTERVAL_DAYS).width
@@ -3264,8 +3282,22 @@ struct VehicleDetailsWindow : Window {
 			case WID_VD_SERVICING_INTERVAL: {
 				/* Draw service interval text */
 				Rect tr = r.Shrink(WidgetDimensions::scaled.framerect);
+
 				SetDParam(0, v->GetServiceInterval());
-				SetDParam(1, v->date_of_last_service);
+
+				/* We're using wallclock units. Show minutes since last serviced. */
+				if (EconTime::UsingWallclockUnits()) {
+					int minutes_since_serviced = (EconTime::CurDate() - v->date_of_last_service).base() / EconTime::DAYS_IN_ECONOMY_WALLCLOCK_MONTH;
+					SetDParam(1, STR_VEHICLE_DETAILS_LAST_SERVICE_MINUTES_AGO);
+					SetDParam(2, minutes_since_serviced);
+					DrawString(tr.left, tr.right, CenterBounds(r.top, r.bottom, GetCharacterHeight(FS_NORMAL)),
+						v->ServiceIntervalIsPercent() ? STR_VEHICLE_DETAILS_SERVICING_INTERVAL_PERCENT : STR_VEHICLE_DETAILS_SERVICING_INTERVAL_MINUTES);
+					break;
+				}
+
+				/* We're using calendar dates. Show the date of last service. */
+				SetDParam(1, STR_VEHICLE_DETAILS_LAST_SERVICE_DATE);
+				SetDParam(2, v->date_of_last_service);
 				DrawString(tr.left, tr.right, CenterBounds(r.top, r.bottom, GetCharacterHeight(FS_NORMAL)),
 						v->ServiceIntervalIsPercent() ? STR_VEHICLE_DETAILS_SERVICING_INTERVAL_PERCENT : STR_VEHICLE_DETAILS_SERVICING_INTERVAL_DAYS);
 				break;
@@ -3288,9 +3320,10 @@ struct VehicleDetailsWindow : Window {
 			WID_VD_INCREASE_SERVICING_INTERVAL,
 			WID_VD_DECREASE_SERVICING_INTERVAL);
 
-		StringID str = v->ServiceIntervalIsCustom() ?
-			(v->ServiceIntervalIsPercent() ? STR_VEHICLE_DETAILS_PERCENT : STR_VEHICLE_DETAILS_DAYS) :
-			STR_VEHICLE_DETAILS_DEFAULT;
+		StringID str =
+			!v->ServiceIntervalIsCustom() ? STR_VEHICLE_DETAILS_DEFAULT :
+			v->ServiceIntervalIsPercent() ? STR_VEHICLE_DETAILS_PERCENT :
+			EconTime::UsingWallclockUnits() ? STR_VEHICLE_DETAILS_MINUTES : STR_VEHICLE_DETAILS_DAYS;
 		this->GetWidget<NWidgetCore>(WID_VD_SERVICE_INTERVAL_DROPDOWN)->widget_data = str;
 
 		this->DrawWidgets();
@@ -3301,8 +3334,13 @@ struct VehicleDetailsWindow : Window {
 		switch (widget) {
 			case WID_VD_INCREASE_SERVICING_INTERVAL:   // increase int
 			case WID_VD_DECREASE_SERVICING_INTERVAL: { // decrease int
-				int mod = _ctrl_pressed ? 5 : 10;
 				const Vehicle *v = Vehicle::Get(this->window_number);
+				int mod;
+				if (!v->ServiceIntervalIsPercent() && EconTime::UsingWallclockUnits()) {
+					mod = _ctrl_pressed ? 1 : 5;
+				} else {
+					mod = _ctrl_pressed ? 5 : 10;
+				}
 
 				mod = (widget == WID_VD_DECREASE_SERVICING_INTERVAL) ? -mod : mod;
 				mod = GetServiceIntervalClamped(mod + v->GetServiceInterval(), v->ServiceIntervalIsPercent());
@@ -3314,7 +3352,9 @@ struct VehicleDetailsWindow : Window {
 
 			case WID_VD_SERVICE_INTERVAL_DROPDOWN: {
 				const Vehicle *v = Vehicle::Get(this->window_number);
-				ShowDropDownMenu(this, _service_interval_dropdown, v->ServiceIntervalIsCustom() ? (v->ServiceIntervalIsPercent() ? 2 : 1) : 0, widget, 0, 0, 0, DDSF_LOST_FOCUS);
+				ShowDropDownMenu(this,
+						EconTime::UsingWallclockUnits() ? _service_interval_dropdown_wallclock : _service_interval_dropdown_calendar,
+						v->ServiceIntervalIsCustom() ? (v->ServiceIntervalIsPercent() ? 2 : 1) : 0, widget, 0, 0, 0, DDSF_LOST_FOCUS);
 				break;
 			}