Table of Contents:

U.S. ATON System

Private Aids to Navigation

Safety Tips

Lateral System

Non-Lateral Aids to Navigation

Uniform State Waterway Marking System

Western Rivers Marking System

Visual Buoyage Guide

Nautical Chart

Bridge Lighting & Other Signals

ATON Abbreviations

USCG District ATON Offices

Report ATON Defects

Aids to Navigation — Road Signs of the Waterway

Bridge Lighting and Other Signals

Bridge Lighting: In U.S. waters, the Coast Guard prescribes certain combinations of fixed lights for bridges and structures extending over waterways. In general, red lights (A) are used to mark piers and supports, and green lights (B) mark the centerline of the navigable channel through a fixed bridge. If there is more than one channel through the bridge, the preferred route is marked by three white lights (C) placed vertically. Red lights (D) are also used on some lift bridges to indicate the lift is closed, and green lights (E) to indicate that the lift is open to vessel traffic. Double-opening swing bridges are lighted with three lanterns on top of the span structure so that when viewed from an approaching vessel the swing span when closed will display three red lights (F), and when open for navigation will display two green lights (G).

Illustration of lighting on a fixed bridge over a main channel. A red light is affixed towards the main support pier on each side of the central span. A green light is affixed to the center of the span. A series of three vertical white lights is affixed to the center of the span. Illustration of lighting on a double leaf (lift) bascule bridge. In the closed position, two red lights are affixed to each pier on either side of the main span and two additional red lights are affixed to the center of the span. In the open position a single green light is attached to each side of the open, raised bridge span.
Fixed Bridge
  		Double Leaf (Lift) Bascule Bridge
 
Illustration of lighting on a vertical lift span bridge that is open. Two red lights are attached at the base of the support piers on either side of the main span. A single green light is affixed to the center of the span. Illustration of lighting on a vertical lift span bridge that is closed. Two red lights are affixed near the bottom of each support pier. An additional red light is affixed to the bottom center of the span.
Vertical Lift Span Bridge (Open)
 		 Vertical Lift Span Bridge (Closed)
 
Illustration of lighting on a double opening swing bridge that is open. Two red lights are affixed to the support piers on either side of the main span and three red lights are affixed to the central support pier. Two green lights are affixed in a vertical arrangement on the central raised part of the span. Illustration of lighting on a double-opening swing bridge that is closed. Two red lights are affixed to the end support piers and three red lights are affixed to the central support pier. A single red light is affixed to the top of the highest portion of the bridge span, while an additional red light is affixed to the second highest points on either side.
Double Opening Swing Bridge
(Open) 		Double Opening Swing Bridge
(Closed)
 

Photograph of a clearance gauge affixed to a bridge pier. The gauge indicates a clearance of 8 feet.Clearance Gauges are extremely valuable to vessel operators because they indicate the vertical distance (clearance) between the "low steel" of the bridge channel span and the waterline (They do not indicate the depth of water under the bridge). These gauges are permanently fixed to the bridge pier or structure and located on the right side of the channel facing approaching vessels. Each gauge is marked by black numbers and foot marks (lines) on a white background board. The picture to the right illustrates a clearance of approximately 7 feet 9 inches, since the 8-foot mark line is not visible.

 

Bridge schematic with a clearance gauge, low steel and waterline.

Drawbridge Opening Signals: The operator of a vessel requesting a drawbridge to open shall signal the bridge tender, and the bridge tender shall acknowledge that signal. The following are the mnost common types of signals a vessel operator should use to request an opening:

  1. Radiotelephone Communications - Most bridges monitor VHF-FM channels 13 and 16 with the exception of bridges in Florida. In June 1996, the FCC published a notice stating that all boaters throughout the State of Florida should hail bridge tenders on VHF-FM channel 9 to reduce the high amount of traffic on channel 13. Boaters operating in Georgia and South Carolina are encouraged to follow the same procedures.
    Note: Boaters should always use "low power (1watt) output" on their VHF-FM marine radio when hailing a bridge tender.
  2. Sound Signals - These signals shall be made by whistle, horn, megaphone, or hailer. To request an opening, the vessel operator shall give the "opening signal" consisting of one prolonged blast (4 to 6 seconds duration) followed by one short blast (about 1 second duration). The draw tender shall reply with the same sound signal (one prolonged followed by one short) acknowledging that the draw can be opened immediately. When a vessel approaches a drawbridge with the draw in the open position, the vessel shall give the opening signal. If no acknowledgement is received within 30 seconds, the vessel may proceed, with caution, through the open draw. When a draw cannot be opened immediately, or is open and must be closed promptly, the draw tender shall give five short blasts sounded in rapid succession after the vessel's opening signal request.

Further information on drawbridge regulations and opening signals for bridges over the Navigable Waterway can be found in the U.S. Coast Pilots.
USCG red rod
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