To meet growing traffic needs, the Idaho Transportation Department (ITD) is expanding and upgrading the State Highway 41 Corridor from Post Falls to Rathdrum to increase capacity and improve safety.

“There is a lot of new development in the area,” says Randy Durland, Project Manager for the south section of the SH 41 project. “The area is growing exponentially and the roads’ current capacity is beyond its design level.”

New residential developments are bringing more people to the area, and retail and commercial spaces are following the new rooftops. About 13,000 vehicles drive on this section of SH 41 daily. With the improvements, it will be designed to carry 21,000.

“This is one of those projects that everyone wanted,” says Megan Jahns, Spokesperson for ITD. “That’s why we have seen good coordination through design and into construction.”

The cities of Post Falls and Rathdrum contributed $5.7 million toward the $51.5 million project.

The project will widen six miles of the road from two lanes to four lanes with several additional signals. The north-south project will add a 50-foot median wherever possible, which allows for future expansion of the road; create a shared-use path on the east side of the road with park benches; and construct a railroad bridge, which will feature stained concrete to match the surroundings. In places where a 50-foot median is not possible, there will be curbing to separate traffic.

The department designed the northern portion from Prairie Avenue to Boekel Road in house. HDR of Omaha, Nebraska, served as the prime designer of the southern portion.

In a separate contract, the department has redesigned the Interstate 90 interchange with SH 41 to improve traffic flow and improve safety. Construction should start on the $73 million project this year.

The department divided the five design projects into two construction contracts at the northern and southern ends of the project.

On the northern end, the team eliminated two at-grade Union Pacific railroad crossings. One crossing was replaced with a twin bridge overpass.

“Not having to stop at the grade crossing has a huge benefit, and we were able to eliminate one of the spur lines,” says Chance Cole, Project Manager for the north portion of the SH 41 project.

Getting rid of that spur line near Prairie Avenue took about a year and half of negotiations with the Surface Transportation Board. Additionally, ITD, Post Falls Highway District, and the City of Post Falls paid for its removal. “There will be a huge increase in safety,” Cole adds.

The spur’s elimination also will help with local traffic on Prairie Avenue and enable the creation of a trail/bicycle path along the former railroad bed. Locals are discussing plans to extend the existing path.

Scarsella Brothers of Kent, Washington, received the prime constructor contracts for both sections. The family-owned company has more than 65 years of experience in heavy civil construction and works throughout the western United States, including an office in Alaska. The company was awarded the I-90 interchange project as well.

Construction began on the northern project in June 2020 and on the southern segment in spring of 2021.

Utility relocations were needed throughout the corridor, requiring coordination with the utility companies and local governments to keep the project on schedule.

“One of the highlights of the south end is Scarsella Brothers ability to cooperate and coordinate with those various utilities,” Durland says. “It’s been very challenging for them, and they have worked diligently to help those folks get out of the way.”

Scarsella Brothers completed the first of two bridges spanning a railroad between Hayden and Wyoming avenues in May 2021. Then work commenced on the second twin bridge. The two bridges are each about 140 feet long and 55 feet wide, with 24 feet of clearance over the rail tracks. A 12-foot path, separated by concrete barriers, has been constructed on both sides of the overpass to allow for future and existing connections. There will be lighting at the bridge and the intersections, and inside the pedestrian tunnel. A tunnel on the north end will connect sidewalks on the bridges.

During the road widening, traffic remained on the existing alignment while the contractor built the northbound lanes. Then traffic shifted to the new lanes, so reconstructive work could progress on the southbound lanes. During construction, alternating intersections are closed to traffic so work can progress for several weeks at a time. Traffic is detoured to alternative intersections.

The contractor is using automated machine grade control for grading of the roadway. The company is using traditional scrapers.

The department is using a special pollinating seed mix, which will be added to the right of way, excluding areas within 20 feet as those sections are managed for invasive weeds. The seed mix will attract bees and Monarch butterflies, Cole reports. There were no other environmental concerns on the project.

Durland states he is most proud of “the coordination with Scarsella Brothers, ITD, the local municipalities, local drivers, and emergency services.”

Cole also praised the coordination and adds, “Drivers will get the payoff in the end.”

The project is scheduled for completion later this year. “We’re excited to wrap up construction on SH 41,” Jahns concludes. “Later this summer, we expect to start construction on the I-90/SH 41 interchange.”

Photos courtesy of the Idaho Transportation Department