Canyon County

Drivers have wanted this stretch of I-84 widened for a decade. It’s finally happening

For years, Canyon County commuters have complained of the bottleneck that forms when Interstate 84 narrows from three to two lanes west of Franklin Boulevard.

While the Idaho Transportation Department spent nearly $500 million to improve a 24-mile stretch of I-84 between Boise and Nampa, most of Canyon County has been left with its two lanes of rough roads — the same number of lanes as when I-84 was first built in 1966.

In those 53 years, the eastern half of a mostly agricultural county has become heavily urban. Nampa’s population has grown from nearly 20,000 to 102,000, and Caldwell’s from 14,000 to 59,000.

But after years of urging from local officials and federal funds won by Idaho’s congressional delegation, work is finally underway to improve I-84 in Canyon County, starting with the stretch between Franklin Boulevard and Midland Boulevard. Eventually, the interstate will be widened all the way to Centennial Way, about 10 miles in all.

ITD officials say drivers could see faster commute times and fewer traffic jams when the project is finished.

Construction crews began work this spring to add a third lane to the interstate in each direction from Franklin Boulevard to Midland Boulevard. Nighttime construction lane restrictions and occasional closures are underway.

The agency is set to spend at least $340 million over the next few years to widen I-84 from Nampa to Caldwell. In the first phase of the project, which ITD aims to complete by 2021, the agency will spend $150.5 million to:

  • Add a third lane to either side of the Interstate between Franklin Boulevard and Midland Boulevard, about 4 miles, plus exit-only lanes.
  • Widen the Franklin Boulevard eastbound off-ramp and modify traffic signals.
  • Replace the Northside Boulevard interchange with a single-point urban interchange.
  • Replace the Karcher Road overpass.

In the second phase of construction, ITD will spend $191.3 million to:

  • Add a third lane to either side of the interstate between Midland Boulevard and Franklin Road, about 4 miles.
  • Replace the Ustick Road overpass.
  • Replace the Middleton Road overpass.
  • Add a sound-wall near Indian Creek Estates.
  • Replace the Linden Road underpass.

ITD is conducting an environmental study for its third phase, which will potentially include widening I-84 from Franklin Road to Centennial Way in Caldwell, about 2 miles, and building sound walls in Caldwell between Centennial Way and 10th Avenue.

As construction progresses throughout the summer, drivers should be on the lookout for the occasional closure, said Amy Schroeder, transportation program manager at ITD.

“We’ll be keeping two lanes open in each direction during the day, and there may be some nighttime closures,” she said.

ITD will first shift traffic to the outside few lanes as they rebuild the median on the inside. Then, it will move traffic to the interior to finish constructing the outside lanes.

For exasperated drivers, the interstate widening has been a long time coming: The Nampa-to-Caldwell stretch has suffered because of a lack of funding for repairs and the expansion.

Drivers coming in from Oregon can tell when they’ve crossed state lines when their cars start to quake. Patches of asphalt are smeared over cracks, where others are left deep and open. Regular commuters tell stories of near misses and accidents they’ve witnessed as drivers lose patience near the exists.

“I have learned to drive with one side of my car right on the solid white line to smooth out the ride just a bit,” wrote Leona Fouts in a comment submitted to ITD.

Caldwell Mayor Garret Nancolas has fought for the project for years and is grateful to see it finally moving forward.

“When the interstate doesn’t function well, it takes time from everyone,” he said in a phone interview.

In 2001, nearly 39,000 cars passed through I-84 at Middleton Road each day. At that time, traffic engineers estimated that in 2020, that stretch would serve 75,000.

It didn’t take that long. By 2018, that stretch saw 80,000 cars passing through it each day, according to COMPASS, the regional planning agency. At the Treasure Valley’s current rate of growth, COMPASS estimates that the same intersection will see 113,000 cars passing through every day by 2025.

Without improvements, travel times will double, COMPASS predicts.

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Provided by Idaho Transportation Department

Getting I-84 funded

Funding for I-84 in Canyon County hasn’t always been a guarantee. In 2014, ITD canceled plans to make road repairs along that stretch after costs came in higher than expected and ITD ran out of money.

ITD receives most of its funding from a state gas tax and the federal government. The Legislature can also authorize ITD to sell GARVEE (which stands for “grant anticipation revenue vehicle”) bonds. The state repays its GARVEE bonds with future payouts from the federal government.

A 2006 bill signed by Gov. Dirk Kempthorne authorized the state to sell $1.2 billion in GARVEE bonds. By 2014, the state had used them all.

Legislators and local officials from Canyon County rallied to have the Legislature authorize more GARVEE funding. Legislators, at first hesitant to saddle future Idahoans with debt, did eventually authorize $300 million in GARVEE bonds in 2017, with much of it slated for the I-84 project.

Then, the state got a pleasant surprise: in 2018, Idaho’s congressional delegation won a $90.2 million grant from the Federal Highway Administration to cover 60 percent of the costs of the first phase. Now, less of not all of the $300 million will be going toward the I-84 widening than legislators had expected, meaning Idaho motorists will shoulder less of the cost than previously thought.

“The Treasure Valley is in a unique position because of the dramatic influx of new residents, more quickly than estimates predicted,” wrote Sen. Mike Crapo in a statement to the Statesman. “It is good to see this strong partnership of congressional leadership, our governor, mayors, county leaders and transportation planners being able to expedite this construction process for this important project.”

Lindsay Nothern, Crapo’s spokesman, said Idaho will likely receive more federal funding.

“We’ll wait to hear from ITD, and if they need the money we’ll certainly go to bat for it,” Nothern said.

Playing catch-up

Melder, of ITD, said adding the new lanes might help for now, but the department can’t always rely on widening the interstate to alleviate traffic.

“We are getting to a point in time on I-84 where just adding lanes is not going to be an option much longer,” he said.

The department is looking into other solutions to congestion, such as adding ramp meters — traffic signals that limits the number of cars entering the freeway.

Highway widening alone rarely relieves traffic — that’s conventional wisdom among transportation planners. In fact, they often make traffic worse, because of a concept called “induced demand:” New roads attract new drivers, both in the form of residents and businesses attracted to the increased capacity. In the end, traffic congestion typically stays about the same.

Plans for a regional transit rail have circulated in COMPASS but have gone nowhere. COMPASS estimates that the capital costs for a commuter rail and bus system to feed it between Caldwell and Boise would cost $693 million, not including the right of way and operating costs. But with no dedicated funding source for rail, it’s nearly impossible to build.

Although COMPASS is still planning for some kind of commuter line, for now the interstate is where most commuters end up.

“Where we’re at, we’re trying to keep up with growth,” Melder said. Part of that means increasing the capacity along other roads within the region. That’s why ITD is concurrently working to widen Highway 20/26 and Highway 44, he added.

ITD’s improvements on routes parallel to I-84 could help disperse traffic throughout the region, Schroeder said.

“It’s an entire network,” Melder added. “We are meeting existing needs and preparing for some future needs.”

For updates on construction, go to, text 84CORRIDOR to 22828, or download the Idaho 511 traveler information app.

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