System Interchange project enters final year of construction

Photograph showing I-15 southbound lane during construction.

The Idaho Transportation Department’s $112 million rebuild of the System Interchange for Interstate 86 and Interstate 15 at Pocatello is entering its final year of construction with crews working in multiple areas throughout the worksite.

Five bridges were built in the last year, bringing the project total up to eight new structures. Two of the new bridges are steel and measure 414 feet long each. The other three bridges are concrete and measure a total of 387 feet in length. The construction of these bridges included 725 feet of 8-foot diameter concrete shafts installed underground for bridge foundations. In addition, 10,000 feet of steel piles were also driven underground for bridge foundations.

The massive project registered other impressive statistics in 2024:

247,319 cubic yards of dirt moved.
143,500 tons of structural dirt imported.
4,000 cubic yards of concrete poured.
55,894 tons of asphalt placed.
568,862 pounds of metal reinforcement installed.

In the coming year several items will be completed to button up the project.

The new southbound-to-westbound ramp will be completed.
The old northbound-to-westbound ramp will be removed.
The temporary southbound-to-westbound ramp will be removed.
The roadway north of the Pocatello Creek on-ramp will be built to its final grade. This will allow movement from Pocatello Creek to Chubbuck and remove the detour currently in place.
The new Chubbuck Road underpass roadway will be completed.
A chip seal will be applied to extend the life of the new asphalt pavement installed by the project, and the road will be restriped to its final lane configuration.
Bridge approaches will be smoothed out to remove bumps made during construction.

Construction is anticipated to be completed in August.

“We appreciate the community’s patience as ITD continues to work with the contractor to button up work items and complete the remaining tasks for this historic project,” Project Manager Greg Roberts said. “ITD is excited to see the travelling public use this updated system interchange for years to come.”

Originally built in the 1960s, the I-86 and I-15 System Interchange is undergoing a rebuild to improve safety and replace aging infrastructure.

Motorists should carefully follow signs and 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 project detours. Project details are available on ITD’s projects website at itdprojects.idaho.gov/pages/i-86i-15-system-interchange.

Chubbuck Road Re-opens to Highland Area

Photograph of the new Chubbuck Road underpass.

The long-awaited reopening of Chubbuck Road has come and traffic is once again flowing from Chubbuck to the Highland area. The Idaho Transportation Department opened the road Friday afternoon to through traffic. However, the new underpass will still require a brief closure next summer to open the road up for pedestrian access.

The Chubbuck Road overpass, built in 1962 was an impediment to large loads travelling north and south on Interstate 15. As part of the System Interchange project the decision was made to transform Chubbuck Road into an underpass with additional facilities for pedestrians and bicyclists. That change necessitated a two-year closure for demolition and the construction of two new bridges to carry I-15 over Chubbuck Road.

Now that the new underpass is open to vehicle traffic, residents in Chubbuck wishing to travel to the Portneuf Wellness Complex or Highland High School will no longer be detoured through the Northgate Interchange.

“We really appreciate the public’s patience during this process,” said Project Manager Zak Johnson. “We’re really excited to have Chubbuck Road open to vehicle traffic again.”

While the road is now open for cars there is expected to be a short closure this summer for approximately two weeks so crews can complete the underpass lanes, curbing and sidewalks.

Originally built in the 1960s, the I-86 and I-15 System Interchange is undergoing $112 million of redesign work to improve safety and replace aging infrastructure.

Motorists should follow all signs and 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.

Pocatello Creek ramp closure scheduled for this week

Drone photo of the System Interchange at Pocatello.

Beginning tomorrow at 7 a.m. the Pocatello Creek Road on-ramp to northbound Interstate 15 will be closed to allow crews to pave the new on-ramp. The closure is expected to last until approximately 5 p.m. Friday. Detours will be in place to guide traffic to the Northgate Interchange or to the Clark Street Exit.

Originally built in the 1960s, the I-86 and I-15 System Interchange is undergoing $112 million of redesign work to improve safety and replace aging infrastructure. The project is scheduled to be completed next summer.

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

Pocatello Creek ramp closure scheduled for tomorrow

Beginning tomorrow at 9 a.m. the Pocatello Creek Road on-ramp to northbound Interstate 15 will be closed to allow crews to remove pavement and to prepare to pave the new on-ramp. The closure is expected to last until approximately 2 p.m. Detours will be in place to guide traffic to the Northgate Interchange or to the Clark Street Exit.

Final full closure for US-20 Rexburg interchange starts tomorrow

US-20 Exit 333 at Rexburg, road closed sign in place with construction equipment surrounding

REXBURG— U.S. Highway 20 Exit 333 for Main Street in Rexburg will fully close beginning tomorrow. This closure allows crews to complete final paving operations and marks the last time Rexburg exits are expected to close for the construction of new diverging diamond interchanges. Exit 333 will be re-opened as soon as paving and striping work is finished, on or before October 29.

“Our goal was to have these projects completed by late fall and that really is going to happen,” Project Manager Conner Huffaker said. “We’re so grateful to the Rexburg community for their support and patience.”

After re-opening, construction efforts at Exit 333 will be largely off the roadway, with only limited lane closures from that point on. Motorists can expect some interruptions as work continues toward final completion, though they will be short lived.

With construction efforts winding down, motorists will also see improvements to timing for the traffic signals at both Exits 332 and 333. Engineers will make signal adjustments until the movement of the new interchanges is ideal for typical traffic flow.

Since March, the Idaho Transportation Department and contractor partners have been working to complete the massive undertaking of rebuilding Exits 332 and 333 in Rexburg. Both exits are now operating diverging diamond interchanges that are expected to resolve former traffic concerns in the Rexburg area.

Cold weather paving in Idaho: how we do it and why it works

Paving, compacting and temperature testing occurring in Idaho with Fall leaves in the background.

The Idaho Transportation Department is overseeing more road construction than ever before. This work continues as temperatures are cooling and the ice and snow make their all-to-soon appearance. How does ITD successfully pave a road and have one of the shortest summer seasons in the country? Materials engineering and testing actually do make it possible.

Before asphalt pavement is ever laid, the surface where it needs to go is sprayed with a binder that will make it stick. This is called tack, a liquid made of oil and water. Tack must naturally break apart to become adhesive, separating as it lays across the surface where paving will happen. As it breaks, tack turns from a brown color to darker black, indicating that breaking has happened, and asphalt can be laid on top.

On the warmest of Idaho summer days, tack breaks in about ten minutes. When it’s colder, it can take hours. Still, with the right process, tack will break. ITD just knows it takes longer and plans accordingly.

Hot mixed asphalt is combined in a hot plant that can heat the components—crushed gravel and oil—to more than 300 degrees. This is dumped from a truck and spread using a paver, then compacted with a roller. ITD inspectors are on site anytime the contractor is, testing temperatures, compaction and much more to ensure that taxpayers get their money’s worth out of each project.

For quality compaction on state highways and interstates, the process must occur between 240-280 degrees. On warm summer days, asphalt must sit for a while after being spread before it is cool enough to be compacted. On colder days, asphalt loads hauled from hot plants are covered in transit to retain the most amount of heat. The asphalt will then be spread, and the roller follows closely behind to compact immediately before the material has cooled too much. All century-old, effective tricks of the trade in action.

“We don’t loosen up our requirements just because it gets cold,” ITD Materials Engineering Manager Mark Hayes said. “All contractors are held to the same quality materials standards and only operate when there are ways to do it right.”

Most of Idaho’s state highways run through rural areas, far removed from permanent hot plant locations. This fall, paving is occurring on State Highway 28 between Leadore and Salmon. The closest permanent hot plant sits in Idaho Falls, nearly four hours away. Enter the mobile hot plant erected by contractors at the ITD Leadore gravel pit, less than five miles from where the asphalt needs to be delivered.

In Rexburg, where paving is still occurring on multiple interchanges off U.S. Highway 20, the contractor’s permanent hot plant lies in Teton, less than ten miles away. Planning to have these proximities ensures that temperature requirements are met, and paving can be done successfully both earlier and later in the year.

Of course, there comes a cold enough ambient daily temperature that means paving operations are simply no longer viable. ITD requires that the temperature be 40 degrees and rising for paving to happen, which can result in fewer hours to pave during the fall but still allows a window of work. The right equipment, materials, planning, testing and operating tricks of the trade make it so ITD and contractors can pave with quality even when it is colder outside.

When you see paving equipment and a compacting roller working close together while your heater is on inside your car, know that ITD and the industry have the brief Idaho summers and cold Idaho temperatures on tap. That new road surface will meet the same metrics as summer paving, ensuring it lasts for many years to come.

US-20 South Rexburg Exit to close starting Monday

Road closed signs at Exit 332 on US-20 in Rexburg.

REXBURG—U.S. Highway 20 Exit 332 for University Boulevard in Rexburg will fully close starting Monday, September 30, for crews to complete final paving and striping operations. Work is not expected to take more than a few days, and the exit will be re-opened as soon as it is completed.

This closure was purposefully scheduled during Madison School District’s harvest break to least affect traffic. Detours include Exit 328 (Thornton), Exit 333 (Main Street) and Exit 337 (North Rexburg). After re-opening next week, construction work at Exit 332 will be minimal and off the roadway.

Construction does continue at Exit 333, with one lane running in each direction. These projects to create safe and efficient diverging diamond interchanges at both Rexburg exits are still expected to be complete later this fall.

For more information about this project, visit https://itdprojects.idaho.gov/pages/us20rexburg. Drivers can also use the 511 app to see current status on this and other Idaho projects.

Repairs start to US-30 overpass near Fish Creek Summit

Beginning tomorrow the Idaho Transportation Department will repair a wildlife underpass on U.S. Highway 30 near Fish Creek Summit. Work will consist of patching the bridge deck.

During construction traffic for both the eastbound and westbound lanes will be restricted to single lanes. Work should be completed in about a month.

Motorists are encouraged to visit 511.idaho.gov or use the 511 app to keep track of delays.

US-20 Exit 333 in Rexburg re-opens

Aerial map and graphic descriptions of how to drive the diverging diamond traffic pattern at Rexburg Exit 333

REXBURG— U.S. Highway 20 Exit 333 in Rexburg will re-open Thursday night with a new diverging diamond interchange in place. This exit has been closed since late July so the Idaho Transportation Department and contractors could construct the new road design and complete vital underground infrastructure work.

The re-opening comes in time for an increase of traffic as university students arrive in Rexburg for the fall semester. All lanes of traffic will be open and construction efforts remain off the roadway at both Exit 332 (University Boulevard) and Exit 333 (Main Street) through this weekend to accommodate this influx.

“There really is a light at the end of the tunnel in Rexburg,” ITD Project Manager Conner Huffaker said. “We’re excited to be giving people some relief from construction and know that these new exits will do a great job of keeping everyone safe and moving better. Thank you for bearing with us.”

Motorists and citizens should be aware that construction efforts will continue again next week and through the month of October. Intermittent single-lane closures will be in place, with traffic still able to move through the interchanges. Impacts will be noted on 511.idaho.gov.

University Boulevard Exit will fully close again during the week of September 30 through October 4 to allow crews to add a final layer of pavement. This timeframe has been selected in coordination with when Madison School District is out of school for harvest break. Work on both exits is on track to be completed late this Fall. For further details about this project and to watch a video on how to drive the new diverging diamond traffic pattern, visit itdprojects.idaho.gov/pages/us20rexburg.

I-15 Woodville Overpass scheduled for repair Tuesday night

Map showing I-15 detour on US-91 for Woodville construction

Beginning tomorrow night at 10 p.m., the northbound lanes of Interstate 15 will be closed underneath the Woodville Overpass so crews can replace a damaged girder. A detour will be in place until 6 a.m. on Wednesday.

Traffic will be detoured off the interstate at Exit 108 to U.S. Highway-91 and then will return to the interstate at Exit 113.

The girder was damaged in November when a towed excavator travelling on I-15 struck the bridge. Traffic on the overpass has been limited to one lane while ITD prepared for the repair. Work will continue until the end of the month when the overpass will be fully open to two-way traffic.

Motorists are encouraged to visit 511.idaho.gov or use the 511 app to keep track of project detours.