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City of Seattle
Ed Murray, Mayor

SUBJECT: New Technology to Help Keep Traffic Moving during Alaskan Way Viaduct Work

10/17/2011  12:30:00 PM

New Technology to Help Keep Traffic Moving during Alaskan Way Viaduct Work

SEATTLE – With the nine-day closure of the Alaskan Way Viaduct only four days away, the City of Seattle, the Washington State Department of Transportation (WSDOT), King County Metro Transit and the Port of Seattle are urging drivers and transit users to plan ahead to avoid significant traffic disruptions. Highlighting the technology being used to monitor and aggressively manage traffic during the work, the partner agencies encourage travelers to take advantage of new systems that can help make trips easier.

SR 99 will be closed for nine full days from 7:30 p.m. Friday, October 21, through 5 a.m. Monday, October 31, for demolition and construction work, leaving drivers without one of the city’s two north-south freeways.

As part of closure preparations, Mayor Mike McGinn today unveiled an upgrade to the city’s Traveler's Information Map that adds cameras streaming live for 12 locations citywide. The pilot program allows viewers to see real-time video of traffic conditions at key road locations. The mayor also announced the activation this week of a new traffic responsive corridor on Aurora Avenue N, adding to the four currently operating, which will automatically sense traffic conditions and adjust signal timing for better flow. These are among many improvements collectively taken to keep people, goods and services moving through Seattle as construction on the south end of the Alaska Way Viaduct gets underway this Friday.

"Our technology investments will help transit riders and drivers have better information, and get to their destinations easier during this major closure," said Mayor McGinn. "Especially with the Traveler's Information Map and its streaming video, residents and businesses can plan before they leave and make the best decision on their route or means of getting to their destination."

WSDOT, in partnership with Metro Transit and the City of Seattle, recognized the potential effects of closures during viaduct replacement construction and invested $125 million in projects designed to keep traffic moving. A portion of this investment funded new electronic driver information signs on I-5, SR 99 and other major routes leading to downtown.

"It is essential WSDOT and its partner agencies work together to provide accurate real-time information to the public," said Matt Preedy, Alaskan Way Viaduct deputy program administrator. "WSDOT's emergency operations center and SDOT's traffic management center will stay in close contact and use traffic cameras to actively monitor traffic conditions during the nine-day viaduct closure. We will pass on information to drivers via new electronic message boards along the SR 99 and I-5 corridors through Seattle."

WSDOT assisted Metro in expanding the downtown and West Seattle bus-monitoring system by adding 21 new readers and modifying eight existing readers. This system allows Metro to monitor bus travel times throughout the corridor to better understand delays from construction activities. The readers were placed in strategic locations to measure changes in transit travel times.

"Metro is using a new bus monitoring system during the viaduct closure that allows our Transit Control Center to more accurately track transit travel times," said Metro General Manager Kevin Desmond. "With this, we can watch how bus routes are affected during major disruptions so that we can make better schedule adjustments in the future. It also helps our control center know where to deploy extra buses during the viaduct closure."

"The region has to keep moving all the time, regardless of construction, and the port is working with shippers, truckers, and our neighbors to do what we can to help during the closure," said Port of Seattle CEO Tay Yoshitani. "By working together, WSDOT, King County, Seattle, and the port are combining efforts to ease what will be a difficult few days for everyone."

The Seattle Department of Transportation (SDOT) has been building a robust Intelligent Transportation System throughout Seattle over the past few years in anticipation of large construction events like the viaduct closure. The system includes: 22 dynamic message signs along roadways; 146 closed-circuit cameras to detect congestion and accidents; traffic responsive technology on five corridors to respond to traffic conditions (Elliott Ave W/15th Ave W, First Ave S, Fourth Ave S, E Marginal Way and Aurora Ave N); and the Traffic Management Center.

The city's camera upgrade is considered a pilot program while the city monitors the impacts to its internet service. If this 12 camera pilot program is a success, the enhanced feature will continue after October Alaskan Way Viaduct construction concludes. The following locations have live streaming available:

West Seattle Bridge Deck Lake City Way NE and NE 125th St
West Seattle Bridge at Delridge 15th Ave NW and NW Market St
Boren Ave and Madison St Montlake Ave NE and 25th Ave NE
Northgate Way N and 5th Ave N Aurora Ave N and N 87th St
E Marginal Way S and S Hanford St Rainier Ave S and S Henderson St
Aurora Ave N and Aloha St Rainier Ave S and S Dearborn St

The Traveler's Information Map is available on SDOT's home page or by visiting

The seismically vulnerable Alaskan Way Viaduct carries thousands of vehicles to and from downtown Seattle, two major stadiums and the Port of Seattle each day. To keep drivers safe and the economy moving, the southern section between S King and S Holgate streets is being replaced with a new side-by-side roadway that meets current seismic standards. For more information, visit the project web site at

For transit options about getting around during the closure and on-going construction, visit:

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