The Colorado Dept. of Transportation begins work in mid-March on its first continuous flow intersection (CFI) project at the U.S. 160/550 west intersection near Durango.

Map courtesy of CDOT
The CFI reconfigures the highway by allowing vehicles to cross to the left side of the highway before the intersection.

CFIs reduce congestion and increase safety at high-traffic intersections, based on other CFIs constructed nationwide. The first CFI in Colorado was built in 2010 by the city of Loveland on Madison Avenue for access onto Eisenhower Blvd./U.S. 34. The one near Durango is the first CFI on a Colorado state highway.

“This intersection sees 30,000 to 45,000 vehicles each day, depending upon the season,” said Region 5 Traffic Engineer Mike McVaugh. “That’s more motorized traffic than any state highway on the Western Slope (including I-70) and about the same amount of traffic as the busiest state highways in Greeley.”

McVaugh and designer/project engineer Tommy Humphrey worked with a consultant to examine several options for the Durango intersection. Extensive analysis showed that neither a roundabout nor a traditional interchange would fit the bill, mainly due to high traffic volumes and cost. Construction cost for the CFI is $6.1 million.

“With the traffic modeling we did, a roundabout could not handle this volume of traffic,” Humphrey said, “and an interchange would have had limited benefits for its additional, much higher cost because of its close proximity—less than 800 ft—to the College Drive signal, as well as future signalized intersections as U.S. 160 continues to develop west of town.”

A CFI effectively removes a left-turn movement from an intersection by reconfiguring the highway to allow vehicles to cross to the left side of the highway in advance of the intersection, allowing for additional concurrent traffic movements not possible at a conventional signalized intersection. These additional concurrent movements increase signal efficiency and provide the opportunity for longer green times for southbound and eastbound movements.

Vehicles traveling northbound on U.S. 550 and turning left onto westbound U.S. 160 (to Cortez) will utilize a new signal to turn in advance of the current stoplight, cross southbound traffic to a new separated cross southbound traffic to a new separated lane, and complete their turn onto U.S. 160 from the new lane.

Other project improvements include:

• Enhanced traffic flow at U.S. 550 (Camino del Rio)/College Drive intersection through reconfiguring the traffic signal and College Drive approach lanes for more efficient signal operation

• Improved bicyclist transportation with bike lanes, bike boxes, green pavement markings, signage and bicycle-capable signal detection

• Improved pedestrian transportation with median refuges, shortened roadway crossing distance through raised-curb islands and medians, raised crosswalks, signing and rectangular rapid flash beacons.

The work is expected to last through mid-August.