diff --git a/src/pbs.cpp b/src/pbs.cpp
index 76a85d935e..a8befd0f7f 100644
--- a/src/pbs.cpp
+++ b/src/pbs.cpp
@@ -84,6 +84,7 @@ bool TryReserveRailTrackdir(TileIndex tile, Trackdir td, bool trigger_stations)
 	bool success = TryReserveRailTrack(tile, TrackdirToTrack(td), trigger_stations);
 	if (success && HasPbsSignalOnTrackdir(tile, td)) {
 		SetSignalStateByTrackdir(tile, td, SIGNAL_STATE_GREEN);
+		MarkSingleSignalDirty(tile, td);
 	}
 	return success;
 }
@@ -183,6 +184,7 @@ void UnreserveRailTrackdir(TileIndex tile, Trackdir td)
 {
 	if (HasPbsSignalOnTrackdir(tile, td)) {
 		SetSignalStateByTrackdir(tile, td, SIGNAL_STATE_RED);
+		MarkSingleSignalDirty(tile, td);
 	}
 	UnreserveRailTrack(tile, TrackdirToTrack(td));
 }
diff --git a/src/rail.h b/src/rail.h
index 6bfb97ce53..41dc1c2125 100644
--- a/src/rail.h
+++ b/src/rail.h
@@ -456,6 +456,8 @@ static inline Money SignalMaintenanceCost(uint32 num)
 	return (_price[PR_INFRASTRUCTURE_RAIL] * 15 * num * (1 + IntSqrt(num))) >> 8; // 1 bit fraction for the multiplier and 7 bits scaling.
 }
 
+void MarkSingleSignalDirty(TileIndex tile, Trackdir td);
+
 void DrawTrainDepotSprite(int x, int y, int image, RailType railtype);
 int TicksToLeaveDepot(const Train *v);
 
diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index 44600cc3a5..f8919fe775 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -2379,7 +2379,7 @@ static uint GetSaveSlopeZ(uint x, uint y, Track track)
 	return GetSlopePixelZ(x, y);
 }
 
-void DrawSingleSignal(TileIndex tile, const RailtypeInfo *rti, Track track, SignalState condition, SignalOffsets image, uint pos, SignalType type, SignalVariant variant, bool show_restricted)
+static void GetSignalXY(TileIndex tile, uint pos, uint &x, uint &y)
 {
 	bool side;
 	switch (_settings_game.construction.train_signal_side) {
@@ -2401,8 +2401,21 @@ void DrawSingleSignal(TileIndex tile, const RailtypeInfo *rti, Track track, Sign
 		}
 	};
 
-	uint x = TileX(tile) * TILE_SIZE + SignalPositions[side][pos].x;
-	uint y = TileY(tile) * TILE_SIZE + SignalPositions[side][pos].y;
+	x = TileX(tile) * TILE_SIZE + SignalPositions[side][pos].x;
+	y = TileY(tile) * TILE_SIZE + SignalPositions[side][pos].y;
+}
+
+static bool _signal_sprite_oversized = false;
+
+static const int SIGNAL_DIRTY_LEFT   =  7 * ZOOM_LVL_BASE;
+static const int SIGNAL_DIRTY_RIGHT  =  7 * ZOOM_LVL_BASE;
+static const int SIGNAL_DIRTY_TOP    = 30 * ZOOM_LVL_BASE;
+static const int SIGNAL_DIRTY_BOTTOM =  5 * ZOOM_LVL_BASE;
+
+void DrawSingleSignal(TileIndex tile, const RailtypeInfo *rti, Track track, SignalState condition, SignalOffsets image, uint pos, SignalType type, SignalVariant variant, bool show_restricted)
+{
+	uint x, y;
+	GetSignalXY(tile, pos, x, y);
 
 	SpriteID sprite;
 	bool is_custom_sprite;
@@ -2457,6 +2470,10 @@ void DrawSingleSignal(TileIndex tile, const RailtypeInfo *rti, Track track, Sign
 	} else {
 		AddSortableSpriteToDraw(sprite, PAL_NONE, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE, GetSaveSlopeZ(x, y, track));
 	}
+	const Sprite *sp = GetSprite(sprite, ST_NORMAL);
+	if (sp->x_offs < -SIGNAL_DIRTY_LEFT || sp->x_offs + sp->width > SIGNAL_DIRTY_RIGHT || sp->y_offs < -SIGNAL_DIRTY_TOP || sp->y_offs + sp->height > SIGNAL_DIRTY_BOTTOM) {
+		_signal_sprite_oversized = true;
+	}
 }
 
 static void DrawSingleSignal(TileIndex tile, const RailtypeInfo *rti, Track track, SignalState condition, SignalOffsets image, uint pos)
@@ -2468,6 +2485,44 @@ static void DrawSingleSignal(TileIndex tile, const RailtypeInfo *rti, Track trac
 	DrawSingleSignal(tile, rti, track, condition, image, pos, type, variant, show_restricted);
 }
 
+void MarkSingleSignalDirty(TileIndex tile, Trackdir td)
+{
+	if (_signal_sprite_oversized || td >= TRACKDIR_END) {
+		MarkTileDirtyByTile(tile, ZOOM_LVL_DRAW_MAP);
+		return;
+	}
+
+	static const uint8 trackdir_to_pos[TRACKDIR_END] = {
+		8,  // TRACKDIR_X_NE
+		10, // TRACKDIR_Y_SE
+		4,  // TRACKDIR_UPPER_E
+		6,  // TRACKDIR_LOWER_E
+		0,  // TRACKDIR_LEFT_S
+		2,  // TRACKDIR_RIGHT_S
+		0,  // TRACKDIR_RVREV_NE
+		0,  // TRACKDIR_RVREV_SE
+		9,  // TRACKDIR_X_SW
+		11, // TRACKDIR_Y_NW
+		5,  // TRACKDIR_UPPER_W
+		7,  // TRACKDIR_LOWER_W
+		1,  // TRACKDIR_LEFT_N
+		3,  // TRACKDIR_RIGHT_N
+		0,  // TRACKDIR_RVREV_SW
+		0,  // TRACKDIR_RVREV_NW
+	};
+
+	uint x, y;
+	GetSignalXY(tile, trackdir_to_pos[td], x, y);
+	Point pt = RemapCoords(x, y, GetSaveSlopeZ(x, y, TrackdirToTrack(td)));
+	MarkAllViewportsDirty(
+			pt.x - SIGNAL_DIRTY_LEFT,
+			pt.y - SIGNAL_DIRTY_TOP,
+			pt.x + SIGNAL_DIRTY_RIGHT,
+			pt.y + SIGNAL_DIRTY_BOTTOM,
+			ZOOM_LVL_DRAW_MAP
+	);
+}
+
 static uint32 _drawtile_track_palette;
 
 
diff --git a/src/signal.cpp b/src/signal.cpp
index 83793d6c64..c9eb234536 100644
--- a/src/signal.cpp
+++ b/src/signal.cpp
@@ -583,7 +583,7 @@ static void UpdateSignalsAroundSegment(SigInfo info)
 				MarkDependencidesForUpdate(SignalReference(tile, track));
 			}
 			SetSignalStateByTrackdir(tile, trackdir, newstate);
-			MarkTileDirtyByTile(tile, ZOOM_LVL_DRAW_MAP);
+			MarkSingleSignalDirty(tile, trackdir);
 		}
 	}
 
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index 5652da6e45..951b1ac7e9 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -2822,7 +2822,7 @@ void FreeTrainTrackReservation(const Train *v, TileIndex origin, Trackdir orig_t
 				} else {
 					/* Turn the signal back to red. */
 					SetSignalStateByTrackdir(tile, td, SIGNAL_STATE_RED);
-					MarkTileDirtyByTile(tile, ZOOM_LVL_DRAW_MAP);
+					MarkSingleSignalDirty(tile, td);
 				}
 			} else if (HasSignalOnTrackdir(tile, ReverseTrackdir(td)) && IsOnewaySignal(tile, TrackdirToTrack(td))) {
 				break;
@@ -3105,7 +3105,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 {
 	Track best_track = INVALID_TRACK;
 	bool do_track_reservation = _settings_game.pf.reserve_paths || force_res;
-	bool changed_signal = false;
+	Trackdir changed_signal = INVALID_TRACKDIR;
 
 	assert((tracks & ~TRACK_BIT_MASK) == 0);
 
@@ -3138,8 +3138,8 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 			ClrBit(v->flags, VRF_WAITING_RESTRICTION);
 
 			do_track_reservation = true;
-			changed_signal = true;
-			SetSignalStateByTrackdir(tile, TrackEnterdirToTrackdir(track, enterdir), SIGNAL_STATE_GREEN);
+			changed_signal = TrackEnterdirToTrackdir(track, enterdir);
+			SetSignalStateByTrackdir(tile, changed_signal, SIGNAL_STATE_GREEN);
 		} else if (!do_track_reservation) {
 			return track;
 		}
@@ -3154,7 +3154,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 		if (res_dest.tile == INVALID_TILE) {
 			/* Reservation failed? */
 			if (mark_stuck) MarkTrainAsStuck(v);
-			if (changed_signal) SetSignalStateByTrackdir(tile, TrackEnterdirToTrackdir(best_track, enterdir), SIGNAL_STATE_RED);
+			if (changed_signal != INVALID_TRACKDIR) SetSignalStateByTrackdir(tile, changed_signal, SIGNAL_STATE_RED);
 			return FindFirstTrack(tracks);
 		}
 		if (res_dest.okay) {
@@ -3165,7 +3165,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 				if (!HasLongReservePbsSignalOnTrackdir(v, ft.m_new_tile, new_td)) {
 					/* Got a valid reservation that ends at a safe target, quick exit. */
 					if (p_got_reservation != nullptr) *p_got_reservation = true;
-					if (changed_signal) MarkTileDirtyByTile(tile, ZOOM_LVL_DRAW_MAP);
+					if (changed_signal != INVALID_TRACKDIR) MarkSingleSignalDirty(tile, changed_signal);
 					TryReserveRailTrack(v->tile, TrackdirToTrack(v->GetVehicleTrackdir()));
 					return best_track;
 				}
@@ -3227,7 +3227,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 			best_track = FindFirstTrack(res);
 			TryReserveRailTrack(v->tile, TrackdirToTrack(v->GetVehicleTrackdir()));
 			if (p_got_reservation != nullptr) *p_got_reservation = true;
-			if (changed_signal) MarkTileDirtyByTile(tile);
+			if (changed_signal != INVALID_TRACKDIR) MarkSingleSignalDirty(tile, changed_signal);
 		} else {
 			FreeTrainTrackReservation(v, origin.tile, origin.trackdir);
 			if (mark_stuck) MarkTrainAsStuck(v);
@@ -3259,7 +3259,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 				FreeTrainTrackReservation(v, origin.tile, origin.trackdir);
 				if (mark_stuck) MarkTrainAsStuck(v);
 				got_reservation = false;
-				changed_signal = false;
+				changed_signal = INVALID_TRACKDIR;
 				break;
 			}
 		}
@@ -3268,7 +3268,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 			FreeTrainTrackReservation(v, origin.tile, origin.trackdir);
 			if (mark_stuck) MarkTrainAsStuck(v);
 			got_reservation = false;
-			changed_signal = false;
+			changed_signal = INVALID_TRACKDIR;
 		}
 		break;
 	}
@@ -3287,7 +3287,7 @@ static Track ChooseTrainTrack(Train *v, TileIndex tile, DiagDirection enterdir,
 
 	TryReserveRailTrack(v->tile, TrackdirToTrack(v->GetVehicleTrackdir()));
 
-	if (changed_signal) MarkTileDirtyByTile(tile, ZOOM_LVL_DRAW_MAP);
+	if (changed_signal != INVALID_TRACKDIR) MarkSingleSignalDirty(tile, changed_signal);
 	if (p_got_reservation != nullptr) *p_got_reservation = got_reservation;
 
 	return best_track;
@@ -4224,7 +4224,7 @@ bool TrainController(Train *v, Vehicle *nomove, bool reverse)
 					Trackdir tdir = TrackDirectionToTrackdir(track, chosen_dir);
 					if (v->IsFrontEngine() && HasPbsSignalOnTrackdir(gp.new_tile, tdir)) {
 						SetSignalStateByTrackdir(gp.new_tile, tdir, SIGNAL_STATE_RED);
-						MarkTileDirtyByTile(gp.new_tile);
+						MarkSingleSignalDirty(gp.new_tile, tdir);
 					}
 
 					/* Clear any track reservation when the last vehicle leaves the tile */