C-470 is a major suburban commuter thruway and critical artery serving the South Denver metropolitan area. The two-lane east-west highway forms the southwest portion of the metro area’s beltway and connects with Interstate 25 and Interstate 70, the state’s most heavily trafficked north-south and east-west corridors. To its east, C-470 becomes E-470, a controlled-access toll road owned and operated by a public highway authority.

Due to significant and undeterred suburban population growth as well as a significant increase in commercial businesses, traffic volumes along C-470 often exceed highway capacity, resulting in frequent gridlock and slowdown. In addition, population growth along the corridor is estimated to increase 21 percent from 2015 to 2035, worsening current conditions. Prior to construction, more than 100,000 motorists used the project area’s segment of C-470 daily. Volumes are projected to increase 40% by 2035.

To improve traffic flows and mitigate additional population pressures on the corridor, CDOT awarded Flatiron a $215 million design-build contract, in partnership with AECOM, to construct several stretches of tolled lanes (one and two-lane eastbound and westbound portions) along a 12-mile segment of the highway, directly west of Interstate 25. Flatiron is leading the fully integrated design and construction team, with AECOM providing construction and design services. The tolled, express lanes (no HOV/Carpool option) will supplement existing non-tolled traffic lanes, allowing motorists to choose between free and paid options, with the paid option conducted through a seamless electronic system installed by Flatiron that is also integrated with a single transponder/toll network used on other metro area highways. 

The project focuses on a particular segment of C-470, between I-25 and Wadsworth Boulevard. In that project area, Flatiron will:

• Add two tolled westbound express lanes from I-25 to Colorado Boulevard, one tolled westbound express lane between Colorado and Wadsworth Boulevard, and one tolled eastbound express lane along the length of the project area from Wadsworth to I-25, as well as constructing auxiliary lanes in select locations

• Replace bridges over the South Platte River and widen existing bridges throughout the project area

• Improve on- and off-ramps

• Install tolling equipment, including Intelligent Transportation Systems

• Construct direct-connect ramps from I-25 to the tolled express lanes, among other project elements

In March 2016, CDOT selected Flatiron from among three shortlisted teams. Award criteria included optimizing traffic along the corridor and meeting project milestones while minimizing public impact during construction.

Add two tolled express lanes on existing westbound C-470 from I-25 to Colorado Boulevard, in addition to constructing eastbound and westbound single tolled express lanes in the 12.5-mile project area

Replace bridges over the South Platte River, as well as widening of existing bridges throughout the project area

Install tolling equipment, including Intelligent Transportation Systems

Construct direct-connect ramps from I-25 to the tolled express lanes