When the two-phase expansion of U.S. Highway 36 between Denver and Boulder is finished in a few years, the roadway will be one of the "smartest" and most innovative in the country. The project, whose first phase is one-third complete, will provide four modes of travel in one place for the first time in Colorado—bus, high-occupancy vehicle (HOV) and high-occupancy toll (HOT) lanes as well as a separate commuter bikeway next to the highway.

The multimodal, design-build U.S. 36 Express Lanes Project is estimated to cost more than $425 million. It is Colorado's first infrastructure project to provide the latest in 24/7 traffic management technology aimed at maximizing safety and minimizing congestion. The technology includes intelligent transportation systems for collecting tolling data and incident management and active traffic management, which employs multiple message signs next to the highway to inform drivers of traffic hazards, delays and weather conditions. The Regional Transportation District (RTD), one of the project's owners and the operator of public transit in the metro area, is studying whether it can add WiFi to buses and stations along the highway.

"We have a facility that was built in the 1950s, and it's worn out," says Mark Gosselin, U.S. 36 Phase 1 project director with the Colorado Dept. of Transportation, the project's principal owner. "The agencies along the corridor are united in wanting multimodal choices. This is the model CDOT is looking at for the future."

The stretch of highway, also known as the Boulder Turnpike, needs improvements to accommodate the population and traffic growth of the last 20 years. CDOT estimates that average daily traffic counts have jumped to as high as 100,000 from 13,774 vehicles in the mid-1960s.

"This project is right in line with what we're seeing nationwide. But I've never worked on a project with the four different modes of travel we're incorporating on U.S. 36," says Brad Johnson, design manager and senior vice president in the Salt Lake City office of Omaha-based HDR Inc., the lead engineering firm for the new express lanes.

Phase 1 Nearly at Peak

The project's $312-million, 11-mile Phase 1 begins at the southern end of the highway. It is about 30% finished, having started construction in summer 2012. It is scheduled to open in January 2015. That work includes adding an express, or managed, lane in both directions, reconstructing pavement, rebuilding or widening several bridges, installing 12-ft-wide inside and outside shoulders and improving existing bus stations. New express lanes will be free for bus rapid transit (BRT) and HOV drivers. Solo drivers can use them for an as-yet-undetermined fee. The existing traffic lanes will remain free.

"We're trying to provide transit priority and travel-time advantage, along with reliability, to encourage people to ride the bus more," says Nadine Lee, RTD program manager for the U.S. 36 BRT. "We're trying to optimize the capacity of the corridor. Instead of carrying three people in three cars, we can carry 55 people on a bus."

Phase 1's design-build team is headed by Burnsville, Minn.-based Ames Construction Inc. and Granite Construction Inc. of Watsonville, Calif., through the Ames/Granite Joint Venture. It also includes engineering firms HDR and Pittsburgh-based Michael Baker Corp. The project is being led by CDOT, the Colorado High Performance Transportation Enterprise (HTPE)—a CDOT financing arm—and RTD.

Peak construction began in late July with the launch of three months of concrete paving; bridge work is well under way. The installation and testing of automated tolling systems are also under way. Crews this summer were working 24 hours a day Monday through Saturday, and sometimes on Sundays for special work such as moving culverts across the highway.

For paving, Ames/Granite is incorporating recycled asphalt and concrete from the old highway. Paving materials are produced at a recently opened fabricating facility located next to the highway in Broomfield. "We're trying to limit throwaway costs," says Jason Estes of Granite Construction and deputy project manager for Ames/Granite JV.

Paving is expected to take 90 to 110 days because contractors want to avoid Colorado's fall snows. Late spring snowfall "crippled us," according to Estes, and contractors are making up for lost time. "We're working double shifts, doing heavy hauling at night and compacting and grading during the day on what's hauled in the night before," Estes says.