Local officials are expressing increasing concerns over the possible effects tolling on the State Route 520 bridge might have on traffic along State Route 522.

They are also showing plenty of skepticism over state projections regarding how many commuters might move their daily drives from 520 to 522, becoming willing to drive around Lake Washington rather than pay to cross the lake via the 520 bridge.

“We believe very strongly there’s going to be a large number of diversions,” said Kenmore Mayor David Baker.

In Bothell, that already mentioned skepticism was on ready display Sept. 7 as City Council hosted Craig Stone, director of WSDOT’s (Washington State Department of Transportation’s) tolling division. Councilman Patrick Ewing said flatly that state estimates of the number of diversions from 520 make “no logical sense.” He said he for one would not pay tolls of up to $3.80 during peak hours.

In the same vein, Bothell Mayor Mark Lamb wondered if any toll proceeds were to be made available to cities impacted by altered traffic patterns, and the short answer was “no.” Stone said the state legislature would need to act to make toll revenues available outside a certain specified traffic corridor.

The state plans to begin tolling on 520 in the spring, with the proceeds going to help replace the aging bridge. Stone said initial state estimates showed as few as 60 drivers altering their routes from 520 to 522 during peak hours in order to avoid the tolls. He added WSDOT officials adjusted those figures in April.

For morning rush hours, the state now estimates 140 diversions to 522, an increase of 8.2 percent in traffic. In the afternoon peak hours, revised figures show 150 diversions or a 6.4 percent traffic increase.

“The modeling today is not showing a dramatic impact on 522,” Stone said, though it was clear councilmembers weren’t really buying his argument.

Stone admitted the state’s projections are just that, projections or estimates. He added WSDOT plans further study once tolling actually begins. Stone said he understands the doubts expressed by officials, but said, even after tolling gets under way, some time may pass before anyone knows for sure what impact the fees have on traffic patterns.

According to Stone, once tolling starts, there will be an inevitable traffic- or driver-adjustment period that could last up to 18 months. He said that initially drivers almost certainly will try a number of different routes, just to see what works best for them. Obviously, traffic also will change depending on the time of day. Stone further insisted tolling is not just a way to raise money, but also an attempt to smooth traffic along 520. He said once that smoothing takes place, more drivers may opt to take the bridge.

Stone said the state’s traffic-diversion estimates are based on information obtained from other tolling experiences both in Washington and around the country. He also said the state did extensive surveying trying to determine the value of time to local drivers. In other words, the state tried to figure how much drivers would be willing to pay to shave five or 10 minutes off their drive time.

In Kenmore, Baker said city officials decided to gather in their own traffic figures. Kenmore City Council authorized traffic counts at a couple of different locations along 522. Officials also plan to complete air-quality studies at spots along the 522 corridor.

“We just want to have our own base numbers,” Baker said.

Officials in both cities noted they have spent a lot of time and, notably, millions of dollars attempting to improve 522 and more work is planned for the roadway in Bothell and Kenmore. Baker claimed the work in his city has all but eliminated traffic backups at several former chokepoints. He added no one wants to see those traffic headaches return. Baker also stated the city is in regular talks with various officials in search of funding in order to complete improvements to a final section of Kenmore’s portion of the roadway.

In Bothell, the city has begun work on a well-advertised, major revamping of 522 that will move the state route south, changing its alignment with Main Street and State Route 527. Officials have said the idea is to help build Bothell’s downtown, but also to improve traffic flow, a flow that now may be impacted by state tolling.