Residents may feel like the last thing Issaquah needs is more traffic backups.

But unfortunately for local drivers, one of the four Interstate 90 crossings in Issaquah closed last week and will remain out of commission until next year.

On the evening of June 26, sections of Southeast 62nd Street and Fourth Avenue Northwest, including the Fourth Avenue crossing under I-90, closed as part of the Southeast 62nd Street extension project. The closure is expected to last until late 2018.

The project will create a new road that extends 62nd Street west to Lake Drive to connect it with East Lake Sammamish Parkway Southeast. Two roundabouts will be put in where the new roadway intersects 221st Place Southeast and Lake Drive.

John Mortenson, senior engineer for the city, explained in an email that the reason for the closure’s long duration is that “a large fill will be constructed in this area to raise the road elevation 15 feet above the existing ground to construct an undercrossing for the East Lake Sammamish Trail and to match the bridge elevation. After the fill is constructed there is waiting period that will last until early January 2018 while the soils under the fill consolidate and settle.”

City of Issaquah Transportation Manager Kurt Seemann called the new road extension “a huge east-west connection in an area that doesn’t have many connections.”

Drivers will be able to cross I-90 at the 17th Avenue Northwest overpass, the Front Street North/East Lake Sammamish Parkway Southeast under-crossing and the East Sunset Way/Highlands Drive Northeast overpass.

The Fourth Avenue under-crossing has been known by some as a “local’s secret” for avoiding the busier traffic backups at the three other over- and under-crossings, which all intersect with freeway off- and on-ramps and provide routes for regional pass-through commuters.

“I’m not too happy to lose that access either,” said Seemann, who himself frequently uses the under-crossing. However, he said, “If we were never to do any construction, we would never disrupt anyone, but we would never have any new projects either … These are short-term impacts, but huge long-term benefits to the city.”

Mortenson said that if no improvements are made, there will be an average of a 173-second delay at the 221st Place and Southeast 62nd Street intersection by 2030. If the project is completed, this will instead be an 11-second delay.

Additionally, Mortenson and Seemann pointed out that the city purposely conducted the East Lake Sammamish Parkway widening, which was completed in 2015, ahead of this project so that drivers would be able to use a large road designed to hold a greater capacity of people than it had done before.

“Widening East Lake Sammamish Parkway before constructing Southeast 62nd Street was key because it allowed East Lake Sammamish Parkway to handle the additional traffic from Fourth Avenue Northwest and 221st Place Southeast,” Mortenson said.

“I don’t see major backups because we first made the improvements to East Lake Sammamish Parkway,” Seemann said. He said that the parkway holds far more drivers than the smaller Fourth Avenue, so while “you’re losing a local bypass route, in terms of volume,” there won’t be too much of an impact.

In addition to the street extension and the roundabouts, the project will widen 62nd Street between East Lake Sammamish Parkway and Lake Drive, will construct two acres of wetland, enhance the North Fork of Issaquah Creek, preserve nearly six acres of property that had been intended for development, improve East Lake Sammamish Trail so users can go under 62nd Street rather than stopping to cross traffic and will add new sidewalks, bike lanes, curbs, gutters, curb ramps and street lights.

Costco is covering approximately $23 million of the $44 million project cost, as the road improvements will improve access for Costco employees to reach the company’s international headquarters on Lake Drive. Seemann said that the development agreement with Costco was a perfect way to help fund a project that had been on the city’s to-do list for years.

“Better connections benefit everybody … We thought it was a great opportunity to partner with a developer and get a roadway that will benefit Costco and will benefit us,” Seemann said. “We’re always looking for ways to make more street connections, and this is one of those.”

With grants from the Washington State Transportation Improvement Board and the Washington State Department of Commerce, the city will only need to fund about 10 percent of the project. Seemann and Mortenson both said that this is a huge boon to taxpayers.

“The citizens are getting all the benefits of this roadway for 10 percent of the cost,” Seemann said.