Could tolls cut 520 traffic in half?



Posted on September 7, 2011 at 7:09 PM

Updated Wednesday, Sep 7 at 11:37 PM

SEATTLE -- New study:  Toll on 520 might cut bridge traffic in half.

How far might drivers on 520 go to avoid paying a toll?  A new study conducted for the Washington State Department of Transportation predicts traffic volume on the 520 bridge could be cut by nearly 50% when the state imposes tolls to go across the highway.

A draft report by Wilbur Smith Associates, a South Carolina consulting firm, says there are many alternatives for drivers who don't want to take 520, unlike the Tacoma Narrows Bridge where commuters had few options but to pay a toll. 

The new 520 study took into account the actual cost of tolls, which have been set at $3.50 each way at peak hour.  The consultant analyzed everything from how long alternate routes would take, to income levels and gas prices.  There would be "changes in destination choice, combining trips, or simply reducing trip frequencies," the study says.

The study also predicts traffic volumes on 520 might not return to today's levels until after the year 2030.

Washington Transportation Secretary Paula Hammond told us, a 50% diversion would be a worst-case scenario.  This study is being used to base revenue projections as the state prepares to sell its first 520 bonds next month.  The Department of Transportation says the consultant is being extremely cautious in projecting toll revenues.  "The financial folks when they look at the traffic and toll analysis; they take a very conservative approach in what diversion might be," Hammond says.

So where would that traffic go?

In a survey of about 2,000 drivers cited in the report, people's preferred alternate routes to the 520 bridge were the I-90 bridge (72 percent) and SR 522 (20 percent). Eight percent said they would choose other routes such as I-5 and I-405.  A small group said they would stop commuting altogether.

Four years ago, the Transportation Department had another study which predicted the traffic drop would be closer to 30 percent. 

At a State Finance Committee meeting today, State Treasurer Jim McIntire told the Governor and Lieutenant Governor that he is using the new study and the higher diversion estimate to make a safe projection on toll revenue.  "That's been built into our projections and our analysis," McIntire says.

The DOT says there's a big difference in studies used for planning and projections made for the bond market.  The Wilbur Smith report qualifies its projections saying, "It is incumbent on the State to make prudent assumptions that will not overstate revenue receipts."