A recent City of Kirkland traffic study shows that 520 tolling impacts on city streets are not as significant as officials expected.

The study of traffic volumes through arterial streets by the City of Kirkland’s Public Works Department was released in a memorandum to Kirkland City Manager Kurt Triplet during the city’s recent annual retreat.

City staff concluded that, “travel time has not changed significantly from pre-tolling values” and that there are no patterns that suggest a significant amount of Kirkland drivers are going north to use 522 as an alternate to tolling.

“Overall, I look at it and see that the changes aren’t that great,” said City of Kirkland Transportation Engineering Manager David Godfrey. “The effects we are seeing could be from tolling but they could also be from other things.”

Some main arterials are seeing some major changes in volumes at certain times of the day but most seem to have no connection to tolling.

“It is a little early to say that there are no changes due to tolling,” said Godfrey. “But I expected more of an impact to be honest. We all prepared for more of a substantial impact … I also expected to see more of a swing as people adjusted and found alternate routes.”

The Public Works Department’s conclusion asserts that the changes seen in the study may not be as clear as the results produced by the Washington State Department of Transportation’s study for tolling effects on other freeway systems. The city’s engineers had to deal with an incomplete history of traffic volumes on newly-annexed streets along with other difficulties.

The WSDOT’s study showed that traffic on the 520 bridge had declined about 41 percent since tolling was implemented on Dec. 29, 2011.

But one of the conclusions of the WSDOT and city is that many drivers have found alternate ways of traveling, or have altered their lifestyle, to avoid the tolls. One of the most concrete examples of this is that Metro ridership with service across the 520 bridge has increased 10 percent.

But the decline of 41 percent in traffic volumes from the 520 bridge and where all those commuters are going has not been completely answered.

“That is the million dollar question,” said Godfrey. “We plan to continue monitoring this … The DOT is doing longer-term studies. When we see that data we might find what people are doing.”

The biggest thing that commuters feel on the arterial routes is a change in travel time. According to the study, most commute times on the main arterials have not changed significantly going north or south near Lake Washington.

Most travel times on Lake Washington Blvd., Market Street, 98th/100th Ave. and Juanita Drive, have not increased by more than about 20 seconds.

Some data shows differences of nearly two minutes but is based on incomplete data, according to the memorandum, and is not considered accurate. Because there was nearly a year between testing times for most of the study, other changes, like population growth, also have to be factored into the results.

The most significant change in commute time with accurate data was actually a traffic-volume reduction. Southbound on Market Street from N.E. 116th Ave. to Central Way during the morning hours, decreased by a little over a minute in the southbound direction.

The other largest change came from N.E. 116th Street and the city limits along 98th/100th Ave. That stretch increased by a little over a minute during the p.m. hours going northbound and decreased by nearly the same amount traveling southbound during that same time of day.

The largest increase in traffic volume is on Lake Washington Blvd. south of N.E. 38th Street, southbound during the evening hours. The study compared volumes from February 2011 to those of February 2012 and saw a 39 percent increase. The increase was the largest of any road in the study based on a single direction at a certain time of day. But it is northbound Lake Washington Blvd. that is the issue with rush-hour traffic during the p.m. hours.

“To take one piece of data by itself is hard to explain,” said Godfrey.

That same stretch of road, traveling northbound in the morning hours saw a 21 percent decrease. This conflicts with the idea that drivers were using that stretch to get from Bellevue to Seattle and around the north part of the lake, unless they were using an alternate route during the morning hours.

Southbound morning traffic volumes saw a 17 percent rise in volume. Overall, Lake Washington Blvd. has seen a 13 percent increase in volume on weekdays during the past year, the largest increase in both directions overall of any road in the study.

The next biggest change came in a study that compared traffic volumes in March 2011 to those in February of 2012. On 96th Ave. south of SR-522, or the northern extension of 100th Ave. into Bothell, the southbound stretch saw a 38 percent increase in traffic volume during the morning hours.

But that same study showed a 23 percent increase in both directions during the morning hours and very little increase during the p.m. hours.

Juanita Drive, west of 98th Ave. N.E., saw northbound traffic volumes in the morning rise 20 percent during the past year. But that same stretch saw and 8 percent decline in volumes in the southbound direction at night.

Juanita Drive’s rush-hour commute is southbound in the morning and northbound at night. Overall, both directions only saw a 3 percent increase in volume on weekdays during the past year.

In a study done comparing traffic volumes in November 2011 to those in February 2012, Juanita Drive north of 141st Street has seen a 24 precent increase in volume during the morning hours traveling southbound, but has remained the same during p.m. hours.