MARYSVILLE — Before schools let out for the day, traffic heading into Marysville is already at a slog.

Even many Sundays now see I-5 jammed to its three-lane gills on the northward trek to Snohomish County’s second-largest city.

A better commute is coming, though it’s still a ways off.

The Washington State Department of Transportation continues to work on plans to open up the right shoulder of northbound I-5 from Everett to Marysville during peak congestion times. The improvement will be paired with a new interchange at Highway 529.

The bundled project, totaling an estimated $84 million, is expected to be complete in 2022.

Meanwhile, Marysville is preparing with a $12 million expansion of First Street. Together, the First Street bypass and the new interchange will help drivers from downtown and the city’s south end reach I-5 without contending with the dreaded railroad tracks on Fourth Street.

“It’s really exciting. It’s going to help alleviate quite a bit of traffic,” said Jeff Laycock, Marysville’s city engineer.

The interchange plan was initially spearheaded by the city, which brought it through initial environmental reviews and other required steps.

Both the $50 million interchange and $34 million peak-use shoulder lane received full funding through the 2015 Connecting Washington gas-tax plan.

The special shoulder lane would extend from Marine View Drive in Everett to Highway 528 (Fourth Street) in Marysville. It would operate like the peak-use shoulder lane on I-405 north of Canyon Park, with signs telling drivers when the shoulder is open to traffic.

Some considerations are still up in the air, however.

One option would reserve the Marysville shoulder lane for carpools only.

Striping also could be affected for the merge points from Marine View Drive and U.S. 2.

WSDOT is working on a preferred approach for the project, spokesman Tom Pearce said. A decision is expected in 2019. It will be up to a contractor to complete the design. The project is expected to go out to bid at the end of 2020.

Right now, a high occupancy vehicle lane is on the left side of the interstate coming into Everett. The HOV lane reverts to a general purpose lane south of Marine View Drive.

In a count last spring, the state identified more than 5,900 northbound vehicles with more than one occupant traveling out of Everett during the peak afternoon rush of 2 to 7 p.m. That was just over one-quarter of the total traffic volume.

Allowing vehicles to drive on the shoulder is a relatively cheap way to add capacity to a busy roadway.

Buses use designated sections of shoulders on I-5 and I-405 when flow is slow.

The shoulder of the eastbound U.S. 2 trestle has been open to afternoon commuters since 2009. Unlike I-405, the shoulder is simply available at set times (now 2-7 p.m. weekdays).

The state also plans to create a peak-use shoulder lane for general traffic on eastbound I-90, from Eastgate to Issaquah, in 2020. That spot also will use electronic lane control signs, like I-405 and I-5.

But I-5 is just one piece of the commuting puzzle for Marysville drivers.

Getting onto the interstate from Fourth Street is a bottleneck, with little room to add lanes.

Then there are those train tracks.

The new interchange is expected to divert 6,000 vehicles per day from the rail crossing on Fourth Street. With train crossings expected to double in the coming years, that’s an even bigger deal.

And there are more people arriving, too.

“With all the growth happening in Marysville, especially in the Whiskey Ridge area … it’s an important step that these projects are happening now and will support that future growth,” Laycock said.

First Street will be widened into an arterial, and be extended from its current end point at Alder Avenue east to 47th Avenue NE. Sidewalks and bike lanes will be added. Construction is expected to start next spring and wrap up by summer 2020.

The city also plans a bridge to cross over the railroad tracks on Grove Street from State Avenue to Cedar Avenue. The overcrossing, estimated at $22 million, is in an early design phase and does not yet have funding for construction.

Street Smarts: streetsmarts@heraldnet.com, 425-339-3432.