diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index bfdfcbfea8..ee3176e6d5 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -1118,10 +1118,12 @@ CommandCost CmdBuildSingleSignal(TileIndex tile, DoCommandFlag flags, uint32 p1,
 						SetBitTunnelBridgeExit(tile);
 					}
 				}
-				SetTunnelBridgeSemaphore(tile, sigvar == SIG_SEMAPHORE);
-				SetTunnelBridgeSemaphore(tile_exit, sigvar == SIG_SEMAPHORE);
-				SetTunnelBridgePBS(tile, is_pbs);
-				SetTunnelBridgePBS(tile_exit, is_pbs);
+				if (p2 == 0 || p2 == 4 || p2 == 8) {
+					SetTunnelBridgeSemaphore(tile, sigvar == SIG_SEMAPHORE);
+					SetTunnelBridgeSemaphore(tile_exit, sigvar == SIG_SEMAPHORE);
+					SetTunnelBridgePBS(tile, is_pbs);
+					SetTunnelBridgePBS(tile_exit, is_pbs);
+				}
 			}
 			if (IsTunnelBridgeExit(tile) && IsTunnelBridgePBS(tile) && !HasTunnelBridgeReservation(tile)) SetTunnelBridgeExitGreen(tile, false);
 			if (IsTunnelBridgeExit(tile_exit) && IsTunnelBridgePBS(tile_exit) && !HasTunnelBridgeReservation(tile_exit)) SetTunnelBridgeExitGreen(tile_exit, false);