If you drive a car in the Puget Sound region, you already know the conclusion of a state Department of Transportation report issued this week. Traffic congestion is getting worse on the area’s freeways.

“We’re certainly seeing a trend,” DOT spokesman Lloyd Brown said Friday.

Data collected from car-monitoring sensors embedded in area highways show traffic conditions significantly worsened between 2003 and 2005, according to the department’s annual congestion report.

“On 34 of the 35 commute routes analyzed, travel times increased at peak periods, speeds slowed, peaks lengthened and the reliability of travel times worsened,” the department said in a Wednesday statement announcing the release of the study.

The biggest reason for the increasing congestion isn’t difficult to discern, according to state traffic engineer Ted Trepanier. State records show some 70,000 people moved to the Puget Sound region during the study period.

“The biggest factor is the area is growing and the infrastructure isn’t,” Trepanier said Friday. “You just have demand outstripping capacity.”

The study is based on information collected on roads in King and Snohomish counties.

Road construction in Pierce County over the past couple of years – adding lanes to Highway 16 and rebuilding the Highway 16/Interstate 5 interchange, for example – made gathering data impractical in the Tacoma area, Brown said.

But traffic engineers believe things are getting worse in the South Sound area, too.

“You can pretty much extrapolate what we’re seeing in King and Snohomish counties right on out,” Trepanier said. “All the South Sound routes are increasing.”

Among other things, the study compared average peak travel times – basically, how long it took to drive from Point A to Point B during rush hour – between 2003 and 2005.

It also compared the duration of the morning and evening rush periods: the amount of time average speeds fell below 70 percent of the posted limit.

Key findings include:

 • Average peak travel times increased on all routes but one: the morning drive from Redmond to Bellevue via Highway 520 and Interstate 405.

Three routes posted 28 percent increases (the highest), including the morning drive from Seattle to Bellevue via Interstate 405/Highway 520/Interstate 5.

The time it took to drive those 10 miles increased from 18 minutes in 2003 to 23 minutes in 2005.

 • Evening commutes are deteriorating faster than morning ones. Traffic engineers say that’s because there are more people traveling for purposes other than work in the evenings. More cars equals longer delays.

 • The morning commute from Federal Way to Seattle is worse than the commute from Everett to Seattle.

That’s because the time the average speed dips below 35 mph on I-5 stretches for 65 minutes during the drive from Federal Way. It lasts for about 50 minutes from Everett.

 • The morning rush period on northbound Highway 167 between Auburn and Renton went from 1 hour and 10 minutes to 2 hours and 25 minutes, an increase of 85 percent.

 • The worst commute was into and out of Bellevue. The longest rush period measured was the evening commute from Bellevue to Tukwila on I-405, which extended for 5 hours and 35 minutes.

State transportation officials are doing what they can to alleviate the growing problem, Trepanier said.

Congestion-reduction measures include building more high-occupancy vehicle lanes – including in Pierce County, where HOV lanes soon will open on Highway 16 – adding meters at on-ramps to better control traffic flow, increasing public transportation alternatives, charging tolls on certain high-demand highways and adding general purpose lanes where appropriate and feasible, he said.

“There is no single solution, and there are big dollars involved,” Trepanier said.

On the Web

To see the state’s latest report on increasing traffic, go to www.wsdot.wa.gov and follow the link to “Annual WSDOT Congestion Report.” Commute times

Not surprisingly, the state Department of Transportation’s annual congestion report shows commute times increasing across the region. While no Pierce County figures were available, here’s a look at two of the most heavily traveled routes in South King County. Note: “Peak period” means the amount of time the average speed fell below 70 percent of the posted limit during rush hour.

morning evening

2003 2005 2003 2005

I-5 from Federal Way to Seattle

Average peak travel time 40 min. 44 min. 34 min. 37 min.

Duration of peak period 2 hours, 30 min. 2 hours, 45 min. 1 hour, 40 min. 2 hours, 5 min.

Highway 167 from Auburn to Renton

Average peak travel time 16 min. 17 min. 16 min. 18 min.

Duration of peak period 1 hour, 10 min. 2 hours, 25 min. 2 hours, 50 min. 3 hours, 5 min.

Adam Lynn: 253-597-8644

adam.lynn@thenewstribune.com