Historic System Interchange rebuild nearing successful completion

Aerial view of the system interchange at Pocatello.

With the painting of final lane markers on the new roadway, construction at the I-86/I-15 “Flying-Y” System Interchange in Pocatello is coming to a successful conclusion. Begun in July 2022, the three-year $112 million project has dramatically changed the drivability of the interchange.

“We spent over eight years from design to actual construction of the project. We’re pretty proud of it. It’s one of the bigger projects we’ve designed. It’s one of the largest projects ever designed entirely by ITD staff and inspected with ITD personnel. Most of the people on the team live here locally and this has been a really meaningful project for us to make sure we did our very best,” said Project Engineer Aaron Baird.

Critical areas that were improved include the northbound Pocatello Creek on-ramp, the northbound-to-westbound collector distributor, and the eastbound-to-northbound ramp. Each of those improvements made merging from one Interstate to the other smoother and safer for motorists.

“We’re excited for people to use the final product. We hope it’s something that will last a long time and keep the travelling public safe as they use it,” said Project Manager Greg Roberts.

The scale of the endeavor has been truly historic. Approximately 1 million cubic yards of excavation have been completed. In addition, about 490,000 tons of base material was brought in; 116,000 tons of asphalt were placed; and over 7,700 cubic yards of concrete were poured. Nearly 70,000 square feet of retaining walls were also built throughout the project area. Finally, ITD built eight new bridges. Four of those have precast concrete girders and four have steel girders. In all, over 5 million pounds of steel has been used in the new bridges.

Construction crews worked year-round and around the clock for approximately three years to complete the project. To minimize disruption to traffic, key demolition operations were conducted at night. These efforts minimized the impact on traffic while the interchange was being reconstructed.

In addition to the major changes inside the Flying-Y design, the Chubbuck Road overpass was reconstructed as an underpass to improve site distances and vertical clearance on I-15, and to improve access to the Wellness Center from Chubbuck. The new underpass is significantly wider and includes bike lanes and sidewalks.

ITD also worked closely with the Portneuf Greenway to construct a pedestrian and bicycle path on the east side of the worksite to connect the Greenway to the Wellness Center.

Work left to wrap up the project will be off the roadway and conducted on the shoulders. In addition, ITD will be seeding open ground with native grasses.

“Thank you for being patient with us and seeing our vision, seeing what we’re trying to do to positively impact this community,” said Project Manager Zak Johnson.

District Engineer Todd Hubbard echoed those sentiments, “This project has been a great success and is an important addition to the community for the safety of drivers. It has been a lot of work to get all of it completed and to keep traffic moving. I want to thank everyone for their patience as we have worked on this project over the last three years. And a thank you to the project team and Sundt-Cannon Joint Venture for a project well done.”

Drivers are encouraged to remain attentive, move over for workers and emergency vehicles, and follow posted speed limits.

Chubbuck Road to open for Fourth of July weekend

Chubbuck road underpass as viewed from the west.

Chubbuck Road is open for traffic under Interstate 15. As part of the redesign of the System Interchange project Chubbuck Road was rebuilt as an underpass with lanes for bicycles and sidewalks. Over the last month the new underpass was closed so crews could build the eastbound lane, construct sidewalks, paint permanent lines and add signs.

ITD expects no further closures of Chubbuck Road. However, crews will continue to work around the site adding vegetation and doing cleanup work. Drivers are encouraged to slow down for workers on and near the roadway.

No cleanup work will occur during the holiday.

Originally built in the 1960s, the I-86 and I-15 System Interchange is undergoing a rebuild to improve safety and replace aging infrastructure. This week crews are painting the final lane lines throughout the project area. Once the lines are completed the remainder of the project will consist of seeding vegetation and other cleanup work that will not affect traffic.

Motorists are encouraged to use 511.idaho.gov or the 511 app to keep track of project detours. Project details are available on ITD’s projects website at itdprojects.idaho.gov/i-86i-15-system-interchange.

Chip sealing to begin Wednesday at I-86 and I-15 System Interchange

Aerial photo of the system interchange at Pocatello.

Beginning tomorrow the Idaho Transportation Department will chip seal the System Interchange in Pocatello. Once this work is complete, the roadway will be restriped to indicate the final lane configurations.

Chip sealing covers temporary lane markings used throughout various phases of construction and maximizes the taxpayers’ investment by extending the lifespan of the pavement. A sticky slurry is sprayed on the pavement then rock chips are applied on top for a long-lasting seal. This treatment protects pavement from sun, oxidation, weather, water, oil and gas, and increases traction for safety.

Tabs will be placed on the new chip seal to indicate lanes for the short time before striping work can occur.

The previous connection between I-86 and I-15 was originally built in the 1960s. Now nearing completion, the System Interchange is a $112 million redesign to improve safety and replace aging infrastructure that began construction in 2022.

Motorists should carefully follow signs and slow down to posted speed limits while traveling through the construction area. With crews working day and night at the System Interchange, it is especially important that drivers be alert and travel safely.

Motorists are encouraged to use 511.idaho.gov or the 511 app to keep track of related detours. Project details are available on ITD’s website at itdprojects.idaho.gov/i-86i-15-system-interchange.

Inkom on-ramp to northbound I-15 (Exit 58) night closures planned for next week

Map of detour in construction area around Inkom.

Due to bridge demolition, the Inkom northbound entrance ramp onto I-15 will be closed for two nights. The West Inkom Interchange northbound entrance ramp (Exit 58) closure will take place from 9 p.m. to 6 a.m. on Monday, June 23 and Tuesday, June 24, weather and other factors permitting.

Traffic will be detoured to Old Highway 91 and then to Exit 63 to head north on I-15. Please watch for crews, use caution, and drive safely.

Due to the nature of the work, considerable noise is expected during the bridge demolition.

The Idaho Transportation Department is in the process of replacing bridges on I-15 at Inkom:

Over the Union Pacific Railroad tracks and Old Highway 91.
Over Rapid Creek Road (Main Street).
I-15 bridges and reconstructing the West Interchange.

ITD combined and streamlined the projects to reduce the construction timeline to approximately two years rather than doing one location at a time over three years. This approach minimizes disruption to the local community and the traveling public and efficiently uses construction funds.

To learn more about the project or sign up for construction updates, please visit: itdprojects.idaho.gov/pages/i15-inkom-corridor. This temporary closure and other traffic impacts will be posted to 511.idaho.gov.

Paving begins north of Blackfoot

A dump truck and paver working on repaving a road.

Tomorrow the Idaho Transportation Department will begin repaving the southbound lanes of Interstate 15 from the Rose/Firth Exit 98 to one mile north of West Blackfoot Exit 93. Traffic will be reduced to one lane in each direction and moved over to the northbound side of I-15.

The project will reconstruct the road to address rutting and potholes. Work is anticipated to be completed in mid-August. The northbound lanes were similarly repaved last year.

Motorists should carefully follow signs and posted speed limits while traveling through the construction area and are encouraged to use 511.idaho.gov or the 511 app to keep track of project detours.

I-84 will close Tuesday and Wednesday nights at the Karcher Interchange

Aerial photo of I-84 Karcher interchange near Nampa, Idaho.

The Idaho Transportation Department will close I-84 under the Karcher Interchange Tuesday and Wednesday nights to place girders on the overpass bridge. Detours will be in place.

Closures will run from 10 p.m. to 5 a.m. each night. On Tuesday night, westbound traffic will be affected, and on Wednesday night, eastbound traffic will be affected.

Motorists traveling westbound on I-84 Tuesday night will:

Exit I-84 at the Northside Interchange (Exit 35).
Travel north on Northside Blvd.
Turn left on to Karcher Road.
Travel west until you reaching the Karcher Interchange westbound on-ramp.
Use the Karcher Interchange westbound on-ramp to merge back on to westbound I-84.

Motorists traveling eastbound on I-84 Wednesday night will:

Exit I-84 using the Karcher Interchange eastbound off-ramp (Exit 33).
Cross Karcher Road.
Use the eastbound on-ramp to merge back onto I-84.

View the detour maps at ITDProjects.idaho.gov/pages/Karcher IC Maps

The girders were fabricated locally and will support the new westbound lane on Karcher Road over the interstate. ITD will host a Facebook live event during the girder placement on Tuesday, June 10. To tune in visit the ITD Facebook page.

Improvements on this project include:

Adding a free running right hand turn at the westbound off-ramp
Paving a third westbound lane on Karcher Road from the westbound off-ramp to Sundance Road
Reinforcing the Karcher Interchange and Indian Creek bridges to support the new lane
Updating signal equipment and adding a pedestrian flashing beacon at the eastbound on-ramp
Building a separated mixed-use path on the north side of Karcher Road

These improvements will increase safety and traffic flow at the interchange. Construction is expected to finish in fall 2025.

Stay informed by signing up for email and text alerts regarding project updates. Text 84CORRIDOR to 1-866-483-8422 or visit itdprojects.idaho.gov/pages/karcheric. For questions, contact the project team at (208) 334-8002. Maps and other details can also be found on the project website.

Construction to begin Monday in American Falls

Map showing final configuration of the intersection of Pocatello Avenue and SH-39

The Idaho Transportation Department will begin construction Monday at the intersection of Pocatello Avenue and State Highway 39 in American Falls. The $3.5 million project will redesign the busy intersection to improve safety.

Work will place a signal at the intersection Pocatello Avenue and SH-39. SH-39 will also be widened to four lanes from the intersection to Fairgrounds Road. New turn lanes will also be built on SH-39 for traffic heading to Pocatello Avenue.

This year construction will take place through August and will focus on realigning and widening the intersection. All lanes will remain open, but traffic will be slowed in the construction zone. Flaggers will be present during different phases of the project. Access to the American Falls Airport and the Power County Fairgrounds will remain open throughout construction.

In the spring of 2026 ITD will return to install the traffic signal. Project details are available on ITD’s projects website at itdprojects.idaho.gov/pages/pocatelloave-i86b.

Night work Tuesday and Wednesday on I-15 at 2.5 Mile Road

The Idaho Transportation Department will move Interstate 15 traffic Tuesday and Wednesday nights to accommodate girder placement at 2.5 Mile Road Bridge.

Traffic will be reduced to a single lane in each direction and shifted onto the same side of the interstate. Work will be conducted between 7 p.m. and 5 a.m. each night with a speed limit of 55 miles per hour through the work zone.

Motorists should carefully follow signs and posted speed limits while traveling through the construction area. With crews working day and night on the project to make I-15 three lanes from Northgate to Fort Hall it is especially important that drivers be alert and travel safely.

I-15 serves as a major transportation corridor through eastern Idaho. These improvements will increase capacity and improve safety to serve the region’s growing transportation needs for years to come.

Expect delays on US-95 for Thorn Creek Bridge work next week

Construction equipment and work zone at Thorn Creek Bridge along US-95.

Daytime intermittent closures on U.S. Highway 95 between Moscow and Lewiston near Thorn Creek/ Uniontown Cutoff will be in effect next Wednesday and Thursday, May 28 and 29, from 6 a.m. to 6 p.m. while the Idaho Transportation Department is installing new bridge girders at the Thorn Creek Bridge.

The bridge will fully close to both north and southbound traffic while each girder is installed. Girders are the large horizontal beams that will support the new bridge deck being constructed this summer.

Flaggers will be present to allow traffic to pass one direction at a time between each girder installation. Motorists are encouraged to seek an alternative route to avoid delays.

This work at Thorn Creek Bridge is part of a large-scale project improving safety along US-95 from Lewiston to Moscow. Portions of this project are funded as part of Idaho Governor Brad Little’s Leading Idaho transportation funding initiative. These funds are used to make investments in critical state infrastructure to enhance safety, mobility and to sustain Idaho’s strong economy into the future.

Digital message boards are currently in place to alert drivers of these closures next week. Updates can also be found on the Idaho 511 app and at https://511.idaho.gov/.

I-15 Stoddard Creek Exit now open to southbound traffic ahead of Memorial Day

I-15 southbound lanes at Stoddard Creek Exit 184 in east Idaho.

Southbound traffic is now able to travel over the Stoddard Creek Bridge at Interstate 15 Exit 184 just in time for the Memorial Day weekend. Travelers can now turn both right and left onto Stoddard Creek Road underneath the bridge. This road provides access to multiple camping and recreational opportunities in the area.

Southbound 1-15 traffic is no longer diverted onto the Exit 184 ramps, but back onto one lane over the Stoddard Creek Bridge along the main roadway. This one lane closure allows the Idaho Transportation Department and contractor partners to accomplish finishing work, like replacing guardrails, on the passing lane of I-15. Work is expected to be complete and all traffic restrictions removed within the next month.

This update can be seen on the Idaho 511 app and at https://511.idaho.gov/.