Dean Wong

It was not a pretty scene. A bus had exploded under the Alaskan Way Viaduct. Part of the aging structure had collapsed on top of the bus and other cars. Injured people cried for help as they waited to be rescued.

Fortunately this was only an emergency exercise. The drill was designed to see how Seattle Police, the Seattle Fire Department, medics, along with City transportation and utility crews, would respond if a real disaster occurred on the Alaskan Way Viaduct.

The Emergency Traffic Management and Closure Plan held last Saturday morning was conducted by the Seattle Department of Transportation (SDOT). It was funded by a $100,000 Urban Areas Security Initiative Grant.

In a real emergency, SDOT would collaborate and consult with multiple agencies, including the Seattle Police Department, Seattle Fire Department, Seattle Public Utilities, Seattle City Light and Emergency Operations Management, the Washington State Department of Transportation and King County Metro.

Seattle Mayor Greg Nickels kicked off the drill.

"The Viaduct and Seawall are the greatest vulnerability we have in Seattle. It has is inspected every six months and it has moved three times since," he said minutes before the 10 a.m. start of the exercise.

After the mayor's address, Seattle Fire Department vehicles began arriving, with a total of 59 firefighters going to work extracting mannequins, setting up ladders, connecting water hoses and assembling a base of operations.

The exercise is one step towards getting the city services ready if something was to bring the viaduct

down. The 2.1-mile Alaskan Way Viaduct is a double deck structure used by over 100,000 commuters each day. The structure was damaged in the 2001 Nisqually earthquake. The seawall under the viaduct was also damaged. The structure was built in the 1950s and does not meet modern earthquake standards.

The 6.8 magnitude Nisqually earthquake caused damage to a portion of the bridge near South

Washington Street and near Royal Brougham Way. Support columns at South Washington Street were shored up since then. Other repairs included expansion joints along the structure. The viaduct has been closed periodically for inspections that reveal wear and tear.

The emergency drill coincided with another two day closure of the old elevated highway as engineers held inspections to check on the condition of the structure and look for any new damage.

In December, the City of Seattle and the Washington State Department of Transportation announced plans to replace the Alaskan Way Viaduct with a $4 billion dollar tunnel.

A delegation of Washington Congressmen secured $231 million towards the project in July from a new federal program for major projects.

"This is a tremendous beginning and we have a lot of work ahead of us to secure all the funding needed to replace this crumbling and dangerous roadway with a tunnel before it threatens people's lives and our region's livelihood. But today I'm happy to say that we've taken another significant step ahead," said Nickels in a statement released on July 28.

Engineers predict the viaduct has a one in 20 chance of failing in the next ten years from an earthquake. In addition, the Seawall which supports the Viaduct was built in the 1930s with steel pilings supported by untreated lumber. It has deteriorated considerably since then.

Failure of the Seawall can cause lateral spreading that can damage Alaskan Way, waterfront piers,

underground utilities and viaduct foundations supported by Seawall fill.

The Emergency Traffic Management and Closure Plan cites natural and man-made hazards that could impact the viaduct. They include a seismic event, major traffic accident, a terrorist act or a structural failure.

In the comprehensive plan, the City addresses four potential scenarios involving the viaduct if it has to be closed for any reason. Any closure of the viaduct means a large amount of traffic has to rerouted. The plan has chosen detours with connections to north and south SR99 routes in mind. It also considers the number of travel lanes available and how they can accommodate trucks and buses. The scenarios in the Emergency Traffic Management and Closure Plan cover four possibilities; a complete closure of the Viaduct and Alaskan Way, a closure of the viaduct only, a temporary closure of the viaduct and a scenario involving tighter weight restrictions.

One to two lane detours in each direction would connect traffic to severed links to SR99. Some traffic

would be re-directed to already congested I-5 and I-90.

The plan clearly states it does not replace the capacity or travel conditions of the viaduct, which normally flows well. No other available detour can provide the Viaduct's traffic speeds and travel times. Each scenario has step by step directions for SDOT to implement. This includes interagency coordination, detailed detours and public communication.

"An emergency closure of the Alaskan Way Viaduct requires more than one department for successful response. Close collaboration is crucial," wrote Grace Cruncian, Director of SDOT.

The highly detailed emergency plan discusses communications, a messaging system to provide instructions to the public, hospitals, trucks, rail and others that will need this information. This includes the possible use of Safeco Field, Qwest stadium and the Seattle Center for any contingency.

The Emergency Traffic Management and Closure Plan is available by logging onto http://www.ci.seattle.wa.us/mayor/issues/viaduct/. Comments can be emailed to viaduct@wsdot.wa.gov. or mailed o Washington State Department of Transportation, 999 Third Avenue South, Suite 2424, Seattle, WA 98104.