What is indicated by red flashing lights on a closed and locked drawbridge?

Red flashing lights on a closed and locked drawbridge indicate that the bridge is in a locked position and no passage is allowed. This warning system is essential for ensuring the safety of both boaters and the structural integrity of the bridge. When the lights flash red, it signifies that the bridge cannot be opened for navigation, and it is crucial for boaters to understand that they must not attempt to pass under the bridge at that time. The presence of red lights acts as a clear and recognized signal to prevent accidents and unauthorized passage. In contrast, other signals—such as solid green lights or different warning configurations—would indicate different statuses regarding the bridge’s operability.