A company that specializes in public-private partnerships is one step closer to designing and building the reworking of C-470, a main but congested artery in the southwest Denver metro area.

Flatiron/AECOM is the preliminary pick over two other companies for the $215 million project.

The Colorado Department of Transportation will now start formal negotiations on the contract.

Flatiron/AECOM — the “Apparent Selected Proposer” for the C-470 project — is part of the Front Range Mobility Group, which has developed and managed over 220 public-private partnerships worldwide, according to the company.

The project calls for adding two tolled express lanes westbound from Interstate 25 to Colorado Boulevard, one tolled express lane between Colorado and Wadsworth Boulevard westbound, and one tolled express lane eastbound from Wadsworth to I-25.

Over 100,000 motorists currently use this segment of C-470 each day with volumes projected to increase 40 percent by 2035.

Construction is slated to start this summer and projected to be completed in the spring of 2019.

Monte Whaley: 720-929-0907, mwhaley@denverpost.com or @montewhaley