Plans call for improvements along C-470, the southwestern quadrant of Denver's almost-full (not quite 360-degree) belt route:
http://www.denverpost.com/news/ci_26979955/cdots-c-470-rebuilding-plan-will-go-traditional
QuoteRather than a public-private partnership between the state and a private firm, C-470 will be widened for toll lanes as a publicly funded, design-build project. That means a company will bid to design and construct the improvements to C-470 but will not manage the highway nor collect tolls. That is how most highway projects in Colorado have been done in the past. ... The $230 million C-470 widening project will add toll lanes in each direction and rebuild various on-ramps along C-470 between I-25 west to about Kipling Parkway. The toll lanes will be "priced to provide a reliable travel time" and will be in addition to the existing four general purpose lanes that will require no user fees, said CDOT spokeswoman Megan Castle. ... Construction is scheduled to begin the summer of 2016 and completed by December 2017.