SEATTLE - Washington State Department of Transportation analysts said Wednesday that tolling on the new viaduct replacement tunnel will cause 30 to 40 percent of traffic that now takes the viaduct to divert to other roads.
Those roads include First Avenue, 4th Avenue, I-5 and even Broadway east of I-5.
In three scenarios, WSDOT considered tolls ranging from as little as 75 cents, to as much as $4 for cars with Good to Go accounts. Drivers paying by mail without an account would have taken on handling fees of another $1.50 on top of that.
The results were announced before the state's Advisory Committee on Tolling and Traffic management. Diversion onto city streets is a big concern for the City of Seattle and many local businesses, who fear regular customers won't be able to get through congested streets.
The state says it needs to toll to cover $200 million of the costs to construct a tunnel running under downtown Seattle. The tunnel will replace what remains of the 60-year-old double deck concrete viaduct considered vulnerable to earthquakes.
Tolling of the 520 floating bridge started in the last days of 2011 and caused similar rates of diversion, primarily on to I-90. But many drivers who swore they would never pay a toll are slowly coming back, and during some short peak periods in the morning and afternoon, traffic levels on 520 are back to pre-tolling levels.