In just a 2-mi. stretch of highway, the Idaho Transportation Department (ITD) is traveling into a new era of road building.
In the first stage of the $18.8-million Twin Falls Alternate Route project, being led by Western Contractors of Boise, ID, two aspects completely new to the Gem State have been included.
The 8-mi. (12.9 km) stretch of roadway, which will become the new U.S. 93 upon its completion, will remove truck traffic from the current U.S. 93, which runs through downtown Twin Falls.
The current roadway, which at one intersection carries 35,000 cars per day, was not built to handle the demands of today’s traffic, said Walter Burnside, ITD’s District 4 resident engineer.
During the roadway’s design phase, ITD officials kept in mind that a major highway will eventually bring in more residential and business development, so crews are using a technique new to Idaho to reduce the amount of traffic noise. Burnside said ITD adapted Minnesota’s standards to fit its own needs.
To create a quieter highway, crews are using a process called carpet drag finish.
Instead of running a tining machine behind a slip form paver as crews construct the concrete roadway, Burnside said workers instead drag an Astroturf-type material longitudinally across the freshly-poured material.
The resulting “microtexture” lessens the amount of noise produced by traffic.
Burnside said the surface, according to the American Concrete Pavement Association, maintains “good skid numbers.”
In addition to creating a more pleasant auditory environment, ITD included a raised planted median along this stretch of the roadway to improve its aesthetics.
While the concrete’s surface is a leap forward in Idaho road building, what lies beneath a 1,000-ft. (305 m) portion of the alternate route could save the state a lot of money in the long run.
Burnside said crews are installing MMFX steel reinforcement in this section for the first time in Idaho.
“It’s the technology of the future,” he said.
This type of steel is more expensive than traditional rebar, but is believed to be less prone to corrosion, thus extending the life of the roadway.
“I think it’s a good investment, but we want to ensure that before it becomes specified statewide,” Burnside said.
Over the course of the next few years, crews will extract the bars and compare them with the traditional rebar in another section of the project to see if the material is living up to its billing.
Burnside said this project is unique in the scope of utility work it requires. There are a large amount of relocations, placement of new utilities to serve the expected growth and upgrades including fiber optic conduit to tie in the signals and other equipment to the state’s developing intelligent transportation system network.
Approximately half of the two-mile portion has been completed, said Western Project Manager Arnie Spriggel.
Western Contractors subbed out the concrete portion of the project to Concrete Placing Co. of Boise, ID, which takes up 25 to 30 percent of the project’s costs.
But the work Western kept for itself has come with its own set of challenges.
As work began in the spring, Spriggel said his crews not only had to deal with a significant amount of utility work, but also active irrigation relocation. Had the project started in the fall, when the irrigation system is inactive, that speed bump would have been nonexistent.
Spriggel said he’s really proud of the fact that his crews completed the one-mile rural stretch of the project in just four months. Work wrapped up in early November ahead of winter shut down.
Approximately 30 workers were at the site, working 10-hour shifts for five or six days a week.
But that doesn’t count those involved with bringing the material to the site.
Approximately 50,000 tons (45,000 t) of base rock and 25,000 cu. yds. (19,000 cu m) of concrete rock were brought from two different sites – a quarry located 20 mi. away and a riverbed located 50 mi. away. Each site had a crusher manned by eight people.
In order to keep ahead of the work at the site, as many as 35 trucks were used to transport the material, he said.
Approximately 40,000 cu. yds. (30,600 cu m) of dirt was moved to make way for the road.
Work will continue through the winter on the reconstruction of a bridge over a perennial coulee, this bridge also has a bike tunnel adjacent to the waterway. This portion of the project is being handled by subcontractor Cannon Builders in Blackfoot, ID.
Cannon will rebuild the bridge in two phases to maintain traffic flow.
Work on the more urban mile of the two-mile stage will begin in the spring.
Spriggel expects to be done with the job by the end of October.
The second stage of the Twin Falls Alternate Route project currently being designed, estimated at $20 million, will include a $7 million steel girder bridge, and will rebuild the county roadway from just west of Grandview Drive to the U.S. 30/U.S. 93 junction completing a truck by-pass route around Twin Falls. Work on this stage is expected to commence upon the completion of stage one. CEG