CDOT to construct Continuous Flow Intersection in Durango - a first on colorado's State Highway System

The CFI is a proven and promising approach to reducing congestion and increasing safety at high-traffic intersections, based on other CFIs constructed nationwide. (The first CFI in Colorado was constructed in 2010 by the City of Loveland on Madison Avenue for access onto Eisenhower Blvd./US 34; a Loveland Reporter Herald article addresses results a year later:  http://www.reporterherald.com/ci_18831980.)

“This intersection sees 30,000 to 45,000 vehicles each day, depending upon the season,” said R5 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 look at various solution options for the Durango intersection. Extensive analysis showed that neither a roundabout nor an interchange would fit the bill, mainly due to high traffic volumes and cost of these options. The total 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 limited benefits for its additional, much higher cost because of its close proximity—less than 800 feet—to the College Drive signal, as well as future signalized intersections as US 160 continues to develop west of town.”

A CFI effectively removes a left-turn movement from an intersection by re-configuring 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 that are 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 US 550 (from Walmart, for example) turning left onto westbound US 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 US 160 from the new lane.

Other project improvements include (see more specific details, below):

• Enhanced traffic flow at US 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, signing, and bicycle-capable signal detection
• Improved pedestrian transportation with median refuges, shortened roadway crossing distance through raised curbed islands and medians, raised crosswalks, signing and rectangular rapid flash beacons

Project Schedule & Anticipated Travel Impacts: The work is expected to last through mid-August 2014. Single-lane closures Monday through Friday during day- and nighttime hours are possible. No weekend work is currently anticipated. More information about travel impacts will be sent to those signing up for updates and posted on the project web site (www.coloradodot.info/projects/us160_us550durangocfi). Next week, crews will begin work between the US 160/550 intersection and 9^th Street on surveying, installing initial erosion control and saw cutting for the removal of the guardrail and handrail in front of Liquor World (business access will be maintained). Motorists should expect some single lane closures during the day.

Sign up for project updates: The best way to stay up to date on project progress, traffic impacts and more is to sign up for email and/or wireless (text) alerts. Go to CDOT's web site at www.coloradodot.info and click on the green cell phone icon in the upper right hand corner of the page. Enter your information and choose "US 160/550 Durango" under the "projects" list. If you would like to reach the project information team directly, please call the hotline at 970-238-1669 or email us at [email protected]. Information will also be updated on the project website at http://www.coloradodot.info/projects/us160_us550durangocfi.

More information on the CFI project’s attention to bicycle and pedestrian traffic:

To serve bicyclist transportation needs, the CDOT, in collaboration with the City of Durango’s multi-modal unit, used national, state and large city cycling engineering design guidance from across the US. The project includes cycling transportation infrastructure treatments that have been successfully implemented on busy roads by cities with robust cycling transportation infrastructure such as Portland, OR, and Boulder, CO.  These cities also provided assistance and input on the project design. Many of the cyclist improvements also have collateral benefits for other modes. Cyclist transportation will be provided with bike lanes, bike boxes, sharrows (bicycle graphic with directional arrows painted on the roadway), green pavement markings, bicycle related signing, and bicycle capable signal detection. Here are the details:

1. Bike Lanes - Current design includes interconnected 5’ to 6’ bike lanes on US 160 West, US 550(Camino) and portions of College Drive.
2. Bike Boxes – Two-stage turn queue boxes (in front of vehicular traffic queue at cross walks) on US 550 and bike boxes on College Drive are planned for installation to facilitate cyclists’ left turns.
3. Sharrows - Where insufficient width is available on Roosa Avenue for right turn lanes, shared lane markings are planned (these are the markings currently used on Roosa Avenue).
4. Green Pavement Markings -Green markings will be used behind on roadway bike symbols, within bike boxes, and at certain locations where bicycles and motorized traffic conflict to enhance cyclist conspicuity.
5. Signing - Signing to emphasize appropriate movements at conflict areas between motorists and cyclists will be installed.
6. Bicycle Capable Signal Detection - A detection system found successful in other areas outside Durango has worked well during  testing at the eastbound 9^th Street approach to Camino del Rio. Also, the northbound US 550 to westbound US 160 bicycle turning movement is currently designed as an exclusive bicycle signal phase (that is, all vehicle traffic movement at the intersection will have a red signal indication while the bicycle movement has a green signal indication.)

To serve pedestrian transportation needs, CDOT also relied on national, state and city pedestrian engineering design guidance.  The project includes pedestrian features that have been successfully implemented on busy roads and state highways by cities such as Boulder on CDOT and non-CDOT projects.  Pedestrians will be provided with refuge and shorter roadway crossing distances by raised curbed islands and medians, raised crosswalks, pedestrian related signing and rectangular rapid flash beacons-

1. Raised curbed medians and islands - Refuge within medians and islands is planned at 7^th Street, US 160 West at the dog park, and three of the four quadrants at US 550 and College.  Pedestrian refuge provides locations for pedestrians to wait that is physically separated from the roadway; the refuge also provides shorter crossing distances. Both of these features improve pedestrian safety and mobility. Raised medians and shorter pedestrian distances also have a collateral mobility and safety benefit to motorists.
2. Raised Crosswalks - For un-signalized right turns with islands, such as at US 550 and College, raised crosswalks will be provided to slow right-turning traffic and emphasize that motorists are to yield to pedestrians.
3. Signing – The project will provide signing (per current national guidelines) that emphasizes where motorists must yield to pedestrians.
4. Rectangular Rapid Flash Beacons (RRFB) - Currently an RRFB is in use at US 550 (Camino del Rio) and 7^th street. The project plans to upgrade the 7^th Street system and install a second such crossing at US 160 West at the dog park. Improvements for the crossings include installing a raised curb median refuge, an RRFB and other signs on the median and roadway and reinforced pavement markings.

“The City greatly appreciated the valuable input given by Durango citizens and businesses through the public outreach,” said Amber Blake, City of Durango’s multimodal administrator. “The cycling and pedestrian components in the CFI offered us an opportunity to partner on a project from our Multimodal Transportation Master Plan.”