Skip Top Navigation

1st Ave South Bridge

1st Avenue South Bridge - Common Questions

When does the bridge open for marine traffic? 
On weekdays from 6 - 9 a.m. and 3 – 6 p.m. the bridge will not open for marine traffic with two exceptions: the bridge will open at any time for a vessel of 5,000 gross tons or more, or for a tugboat going upstream to get a vessel of 5,000 gross tons or more. The bridge is opened upon request outside of peak hours, on weekends and all federal holidays except Columbus Day.

Historically, marine traffic has the right-of-way on many waterways around the Puget Sound. Maritime law pre-dates most other law. 

Can WSDOT request a change to marine openings?
Changing the hours is a long and complicated process that literally requires an Act of Congress. Because the Duwamish Waterway is a critical cargo waterway, WSDOT must balance the needs of people and the economy. No one can control the tides and many of these boats are dependent on the tides to move in and out of the area. 

The mission of the Washington State Department of Transportation is to keep people and business moving by operating and improving the state’s transportation systems vital to our taxpayers and communities. That includes the marine imports and exports that are so important to our economy.

Making operational changes to moveable bridges requires Congressional approval. First WSDOT must demonstrate a need to change the hours. To do that, we need comprehensive traffic studies of car counts and patterns. The area around the 1st Avenue S. Bridge has few traffic sensors to monitor traffic. New sensors and stoplights installed in the summer of 2010 will provide us with better data. WSDOT must make a request to the local Coast Guard for a change in operating hours. If the local Coast Guard office approves, the request is then sent to the Coast Guard headquarters in Washington, D.C. for review. The proposal will be then open to public comments. After the public comment period, the Coast Guard can then submit it to Congress for it to be written into law and voted on. This process can take two-three years.
What about short term changes to restricting marine traffic?
“Short term” is defined as anything that lasts 59 consecutive days or less. A short term change can be approved by the local Coast Guard office. Anything beyond 59 days must be approved by Congress.

How long does an opening last?
It depends on what type of marine vessel is going through. Some can take as little as five minutes, while others may last 30 minutes or more. The average opening lasts just under 11 minutes. However, it can take 20-30 minutes for the resulting congestion to dissipate. 

How come it seems like I wait longer than the traffic on the other end the bridge when there's an opening?
Our bridge tenders follow very strict protocol for opening and closing the spans. The first span that opens is always the first span that closes. That helps ensure that drivers on either end of the bridge wait approximately the same amount of time.

It seems like one drawspan opens first and then the other. Why can't you open them at the same time?
The bridges were built forty years apart and operate using completely different systems. The old bridge uses a gear-like mechanism, while the newer bridge operates using hydraulics. There are two separate control panels for each bridge.

Because of the complexities involved, the bridge operator can only open one at a time to ensure the safety of drivers and boats. Once one bridge is opened, the tender can then concentrate on opening the second one. Occasionally, you will see both bridges open and close at the same time. When that happens, it means there is a second operator in the bridge tower and the two are each operating a bridge. 

Why aren't there the same number of upstream openings listed as downstream on your bridge openings web page? Both spans are always opened for a boat.
We count upstream and downstream openings separately because we are noting the direction of the boat. Any number of factors can dictate whether an opening is required including the size of the boat and the tide.

For example, a tugboat going upstream to retrieve a barge may not need the bridge opened because it fits through it just fine. But several hours later, when it is pulling the barge downstream it may need the drawspan opened because the tide may be high or the barge may be too large to fit under the bridge.