What color lights are utilized to directly indicate the main navigable channel on a multiple span bridge?

The main navigable channel of a multiple span bridge is indicated by white lights arranged in a vertical line. This specific color and arrangement of lights serve as a clear signal to mariners about the safest route to take when navigating through or under the bridge. Such markings help to guide vessels safely and efficiently, ensuring they stay within the navigable channel, away from potential hazards.

In navigation, white lights typically denote safe passage, while other color indicators—such as red or green—are often used in conjunction with buoys and other navigational aids to indicate different aspects of navigation, such as port and starboard sides. The positioning of the lights in a vertical line provides additional visual clarity and assists in the identification of the channel, especially in low visibility conditions.