diff --git a/src/table/company_settings.ini b/src/table/company_settings.ini
--- a/src/table/company_settings.ini
+++ b/src/table/company_settings.ini
@@ -5,19 +5,16 @@
 ;
 
 [pre-amble]
-static bool CheckInterval(int32 p1);
-static bool InvalidateDetailsWindow(int32 p1);
-static bool UpdateIntervalTrains(int32 p1);
-static bool UpdateIntervalRoadVeh(int32 p1);
-static bool UpdateIntervalShips(int32 p1);
-static bool UpdateIntervalAircraft(int32 p1);
+static void UpdateServiceInterval(int32 new_value);
+static bool CanUpdateServiceInterval(VehicleType type, int32 &new_value);
+static void UpdateServiceInterval(VehicleType type, int32 new_value);
 
 static const SettingTable _company_settings{
 [post-amble]
 };
 [templates]
-SDT_BOOL = SDT_BOOL($base, $var,        $flags, $guiflags, $def,                        $str, $strhelp, $strval, $proc, $from, $to, $cat, $extra, $startup),
-SDT_VAR  =  SDT_VAR($base, $var, $type, $flags, $guiflags, $def, $min, $max, $interval, $str, $strhelp, $strval, $proc, $from, $to, $cat, $extra, $startup),
+SDT_BOOL = SDT_BOOL($base, $var,        $flags, $guiflags, $def,                        $str, $strhelp, $strval, $pre_cb, $post_cb, $from, $to, $cat, $extra, $startup),
+SDT_VAR  =  SDT_VAR($base, $var, $type, $flags, $guiflags, $def, $min, $max, $interval, $str, $strhelp, $strval, $pre_cb, $post_cb, $from, $to, $cat, $extra, $startup),
 
 [validation]
 SDT_VAR = static_assert($max <= MAX_$type, "Maximum value for $base.$var exceeds storage size");
@@ -29,7 +26,8 @@ interval = 0
 str      = STR_NULL
 strhelp  = STR_CONFIG_SETTING_NO_EXPLANATION_AVAILABLE_HELPTEXT
 strval   = STR_NULL
-proc     = nullptr
+pre_cb   = nullptr
+post_cb  = nullptr
 load     = nullptr
 from     = SL_MIN_VERSION
 to       = SL_MAX_VERSION
@@ -82,7 +80,7 @@ var      = vehicle.servint_ispercent
 def      = false
 str      = STR_CONFIG_SETTING_SERVINT_ISPERCENT
 strhelp  = STR_CONFIG_SETTING_SERVINT_ISPERCENT_HELPTEXT
-proc     = CheckInterval
+post_cb  = UpdateServiceInterval
 
 [SDT_VAR]
 base     = CompanySettings
@@ -95,7 +93,8 @@ max      = 800
 str      = STR_CONFIG_SETTING_SERVINT_TRAINS
 strhelp  = STR_CONFIG_SETTING_SERVINT_TRAINS_HELPTEXT
 strval   = STR_CONFIG_SETTING_SERVINT_VALUE
-proc     = UpdateIntervalTrains
+pre_cb   = [](auto new_value) { return CanUpdateServiceInterval(VEH_TRAIN, new_value); }
+post_cb  = [](auto new_value) { UpdateServiceInterval(VEH_TRAIN, new_value); }
 
 [SDT_VAR]
 base     = CompanySettings
@@ -108,7 +107,8 @@ max      = 800
 str      = STR_CONFIG_SETTING_SERVINT_ROAD_VEHICLES
 strhelp  = STR_CONFIG_SETTING_SERVINT_ROAD_VEHICLES_HELPTEXT
 strval   = STR_CONFIG_SETTING_SERVINT_VALUE
-proc     = UpdateIntervalRoadVeh
+pre_cb   = [](auto new_value) { return CanUpdateServiceInterval(VEH_ROAD, new_value); }
+post_cb  = [](auto new_value) { UpdateServiceInterval(VEH_ROAD, new_value); }
 
 [SDT_VAR]
 base     = CompanySettings
@@ -121,7 +121,8 @@ max      = 800
 str      = STR_CONFIG_SETTING_SERVINT_SHIPS
 strhelp  = STR_CONFIG_SETTING_SERVINT_SHIPS_HELPTEXT
 strval   = STR_CONFIG_SETTING_SERVINT_VALUE
-proc     = UpdateIntervalShips
+pre_cb   = [](auto new_value) { return CanUpdateServiceInterval(VEH_SHIP, new_value); }
+post_cb  = [](auto new_value) { UpdateServiceInterval(VEH_SHIP, new_value); }
 
 [SDT_VAR]
 base     = CompanySettings
@@ -134,4 +135,5 @@ max      = 800
 str      = STR_CONFIG_SETTING_SERVINT_AIRCRAFT
 strhelp  = STR_CONFIG_SETTING_SERVINT_AIRCRAFT_HELPTEXT
 strval   = STR_CONFIG_SETTING_SERVINT_VALUE
-proc     = UpdateIntervalAircraft
+pre_cb   = [](auto new_value) { return CanUpdateServiceInterval(VEH_AIRCRAFT, new_value); }
+post_cb  = [](auto new_value) { UpdateServiceInterval(VEH_AIRCRAFT, new_value); }