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The Arkansas Department of Transportation has all the pieces in place to improve the Cantrell Road/Interstate 430 interchange in west Little Rock.

But people can't expect dirt to be turned in earnest for another three years.

The Arkansas Highway Commission on Tuesday approved Garver LLC, the multidisciplinary engineering services firm based in North Little Rock, as the engineers' estimating consultant for the project, which has an estimated price tag of $58 million.

The selection came two months after commission approval of Kiewit Infastructure South of Fort Worth to help design the project and Innovative Contracting & Engineering of Las Vegas to serve as an independent cost estimator that will work with the contractor and the design team.

The three companies have been engaged to help the department undertake its first project using the construction manager/contractor method in which the construction manager -- in this case, Kiewit -- will work side by side with the department's design team to help control costs and manage traffic during construction.

Typically, projects are designed and then put out for bid, with the lowest bidder winning the job.

Last week, the department signed contracts with Kiewit and Innovative Contracting & Engineering and held a day-and-a-half-long meeting to discuss a preliminary schedule and other matters, said Scott Bennett, the department's director.

"The process has started," he said.

Kiewit will work alongside the department's design team to provide practical advice from an experienced contractor for what is expected to be a complicated project.

"It won't be designed in a vacuum," Bennett said.

That section of Cantrell Road, which is also called Arkansas 10, is the busiest noninterstate thoroughfare in the state, with up to 54,000 vehicles traveling between Pleasant Valley and Pleasant Ridge roads every day. A study of the corridor has projected, thanks to the surging development in the area, that 76,000 vehicles will be using Cantrell daily in 20 years.

The project is centered on a single-point urban interchange design in which the section of Cantrell, widened to six lanes from four, will have traffic go over the North Rodney Parham Road intersection rather than through it, as Cantrell does now.

The elevated roadway is similar to the ramp that carries traffic on Interstate 630 over South Shackleford Road in the Interstate 430/Interstate 630 interchange.

The "single point" in the interchange design would be underneath Cantrell at North Rodney Parham. One traffic signal would control traffic moving onto or off Cantrell, which would allow motorists going east and west on Cantrell to avoid stopping at a light to accommodate North Rodney Parham traffic, a feature that is a source of much of the congestion in the corridor.

The design also includes a feature popularly known as a "Texas turnaround," which will allow drivers traveling south on I-430 to turn east on Cantrell. Motorists actually would travel west for a short distance, then make what amounts to a U-turn back to the east.

The Texas turnaround would replace a loop ramp that traffic now uses to go from southbound I-430 to eastbound Cantrell and would eliminate an element that has the southbound I-430 traffic merging into the same lane used by eastbound Cantrell traffic to access I-430 north.

The new interchange also will feature a traffic circle north of Cantrell and opposite North Rodney Parham that would serve traffic for the Walton Heights neighborhood, River Mountain Road and a bank and church facing Cantrell.

By allowing Kiewit to work closely with the design team, the hope is to avoid any surprises once construction begins, Bennett said.

Using the new construction method will allow the design team to put together a "better project, faster and more efficiently," he said, adding the design team will be working on "constructability and phasing issues" before the majority of the work begins.

The design work isn't expected to be complete until a year from now, Bennett said. At that point, the necessary rights of way will be acquired. Utility relocation isn't expected to finish until the middle of 2021, at which time construction can begin.

Part of the design work will be figuring out what parts of the project might be able to be built before 2021, Bennett said.

As part of the new construction method, Kiewit will have the opportunity to submit a bid to do the work without involving other contractors.

This is where Garver figures in the project. It will be Garver's job to closely monitor the work of Kiewit and the department's design team and come up with its own project cost estimate, a figure that won't be shared with Kiewit, only department officials.

Kiewit's figure will be compared with the one developed by Garver. If Kiewit's number is within 10 percent of the Garver number, Kiewit will be awarded the contract to construct the project.

If it isn't within 10 percent, the project will go through the normal bidding process. Kiewit wouldn't be precluded from submitting another bid at that point.

Some work already has been done on the interchange. Kiewit was the contractor that recently completed the $22.9 million construction of a ramp from Cantrell westbound to I-430 northbound.

The project construction method is permitted by Act 809 of 2017, which allows the department to use the method on up to three pilot projects not to exceed $200 million in total cost. Only one project at a time can be built under the manager/contractor method.

Metro on 04/25/2018

Print Headline: Road project's last firm OK'd; But Cantrell/I-430 junction revamp still years off, state says

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