The city of Snoqualmie has come to the cities of Maple Valley, Covington and Kent for help to fund an interim ramp at the Interstate 90/State Route 18 intersection while the Washington State Department of Transportation completes a Diverging Diamond Interchange (DDI).

Snoqualmie spent $130,000 to hire an engineer to come up with different plans to improve the I-90/SR 18 interchange, and then went to WSDOT with their idea. That’s when they came up with the DDI idea, Snoqualmie Mayor Matt Larson said.

“In a traditional diamond interchange, three phases are required to move traffic through the interchange, including a separate phase for left-hand turns. In a DDI, through-traffic and left turns happen at the same time, eliminating the need for a separate left-turn phase,” according to an article on WSDOT’s website.

According to Larson, he thinks WSDOT liked this idea because it was not only cheaper than the original “fly over ramp” plan they had, but also there could be leftover money, which WSDOT might use toward widening SR 18 from Hobart to Raging River, Larson said.

Tentatively, construction for the DDI will begin in 2021. The DDI is proven to reduce collisions and to keep the flow of traffic moving, it said on WSDOT’s website.

While the construction for this project is being done, traffic congestion and back ups will be undeniable.

To combat this, the city of Snoqualmie went to WSDOT and introduced the idea of an interim ramp that will allow drivers to get onto I-90 West from Snoqualmie while construction is going on.

Covington City Manager Regan Bolli said the problem with this project idea is WSDOT considered it a “throw away” project because it will be ripped out once the DDI is completed or close to completion.

“They certainly didn’t want to take one nickel out of the $150 million (DDI budget) and put it toward what they considered a ‘throw away’ project,” Larson said.

The city of Snoqualmie agreed to come up with $650,000 to go toward this $1.25 million temporary on-ramp.

According to Maple Valley City Manager Laura Philpot, Snoqualmie has been able to come up with $450,000 by asking its residents if they would be willing to pay a $20 car fee.

Larson said this tab fee will generate between $200,000 to $225,000 a year in revenue for two years.

“They heard overwhelmingly support for that from the outreach that they did,” Philpot said.

That left Larson with a gap of $175,000 to fill, which is where Covington and Maple Valley come into play.

According to a slideshow presented to Covington and Maple Valley city councils, Snoqualmie is asking for $50,000 from each of these cities, and $15,000 from Kent to make up the rest of the promised funds.

Snoqualmie has specifically reached out to these three cities because residents from the cities use this on interchange quite frequently.

About 1,410 Maple Valley commuters use the SR 18/I-90 interchange in the morning and about 1,252 Covington vehicles use the interchange as well, it stated on the slideshow.

“I think they (Covington and Maple Valley) have a measurable, notable impact on this (the interchange),” Larson said.

The hope, according to Bolli, is for the interim ramp to stay put for the entirety of the four years it is estimated to take to complete the DDI project, but he said that might not be likely.

“WSDOT said they may want to pull this out, that it may only last a couple of years as opposed to (lasting) the whole project because they may have to use a portion of this (area) for some of the construction, but I think that’s unlikely,” Bolli said.

Larson said WSDOT committed to two years for sure, but could not guarantee it will last to the end of the project.

Neither Covington or Maple Valley council members have made a final decision as to whether or not they will contribute funding to the interim ramp.

Bolli said the Covington Council is deliberating, but said they are leaning toward saying “yes,” they will help fund this interim project.

The funds would ideally come from the city’s contingency fund.

“Typically those aren’t spent by city council each year. So those funds are most likely what would be applied to this,” Bolli said.

Covington City Council is scheduled to make a decision regarding the funds at the March 26 meeting.

Philpot said Maple Valley is also still deliberating.

“At this time, we’re still in the evaluation phase. The council has assigned a council committee of (council members) Syd Dawson, Linda Olson and Les Burberry to look at it in more detail (then) come back with a recommendation,” she explained.

A final decision should come from Maple Valley by April, according to Philpot.

Construction for the interim ramp will start as soon as Snoqualmie can gather the funds needed and could open up as early as fall 2019, Bolli said.