Traffic on Interstate 90 westbound through Issaquah in the mornings is typically pretty sludgy.
But that slow spot will worsen until 2030, when traffic will move slower than 30 miles an hour for about three hours every weekday morning from Highlands Drive to Lakemont Boulevard — if no major improvements are made.
Such was the worst-case scenario that state Department of Transportation officials painted for the City Council’s Committee of the Whole meeting on Tuesday.
What was scheduled to be a 15-minute debriefing on the future of I-90 turned into more than an hour of questions from the council.
“We are very concerned with traffic,” Councilman Dave Kappler told the WSDOT representatives.
WSDOT gave both the current traffic conditions of I-90 and what the predictions are for 2030 for the stretch of the interstate that passes through Issaquah.
The traffic estimates for 2030 were made on the assumption that no work would be done along the Issaquah stretch.
“I commend you on your attempt to look 22 years in the future,” Councilman Josh Schaer said. “There are a lot of factors.”
The area around the Lakemont exit is predicted to have an increase in traffic of more than 50 percent, the second-highest increase predicted along all of I-90.
Unfortunately, Issaquah also has the dubious honor of having the highest increase as well, along the Sunset exit, which is predicted to go up anywhere from 43 percent to 72 percent depending on the time of day.
These numbers did not factor in any impact tolling might have on I-90 traffic. Those numbers are still being calculated and should be available next month, officials said.
Also not factored in was the removal of the Southeast Bypass, which the council voted down in March. Although this shouldn’t have a huge effect on most of I-90, it will affect the interchange at Front street, WSDOT consultant Torsten Lienau said.
“It’s not a simple thing to take out,” Lienau said after council members asked how their decision earlier this year affected the future traffic numbers.
The council also heard about some near term and long term solutions to the traffic on I-90, including more mass transit, shoulder usage during peak hours and turning HOV into HOT lanes similar to the current pilot project on Highway 167 in South King County.
Long term goals include an overcrossing near State Route 900 and a Front Street Flyover.
Councilman Fred Butler pointed out that the city already has plans for an I-90 undercrossing.
The undercrossing has been delayed until 2009, following a SEPA appeal. City staff members are currently updating the traffic model for the SEPA review to move the project forward. City officials still need to finalize the purchase of the Zetec property, as well as work out the rights of way with WSDOT.