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Linking Lookout: US 6 and 19th Street Interchange

Golden, Colorado

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In addition to 60,000 vehicles, hundreds of residents, cyclists, and Colorado School of Mines students navigate the US 6 and 19th Street intersection in Golden each day traveling between neighborhoods and downtown, up Lookout Mountain, and between classes and student housing. The US 6 and 19th Street interchange (Linking Lookout) replaced the existing signalized intersection with a modified diamond interchange featuring a city park and multi-use trails built on the first landscaped bridge and innovative highway lid in Colorado.

For the CDOT 1601 Interchange Approval Process, Muller completed traffic operations analyses, including Synchro and VISSIM Modeling for the interchange alternatives considered. For final design, Muller traffic engineers developed the traffic operational improvements for two temporary signalized intersections used during construction and a permanent roundabout. As lead roadway designers for the project, Muller prepared geometric design for relocation (lowering) of US 6, alignment changes for 19th Street, interchange ramps, multi-use trails, and the intersections associated with the interchange. A very talented group of women led the way by undertaking key project leadership roles.

The modified diamond interchange design at US 6 and 19th Street called for lowering US 6 with 19th Street reconstructed on its current grade. The structure used for the grade separation of 19th Street over US 6 is a “lid” approximately 270 feet wide that carries 19th Street and bike and pedestrian facilities across US 6, along with a park area with landscaping and user amenities. A unique geometric configuration keeps pedestrian and bicycle traffic separated from vehicular traffic and provides traffic operations at the ramp terminals without the use of traffic signals. The primary movements between downtown Golden and Denver and Lakewood all move freely to and from 19th Street without stopping. A roundabout replaced an intersection at Elm Street and 19th Street east of the interchange to improve operations along 19th Street in the interchange area.

Another key project element is the landscaped bridge or lid itself. To minimize US 6 excavation, thin side-by-side box girders were used for the superstructure. Special drainage board and waterproofing was used on the bridge deck to carry away rain and irrigation water infiltrating through the park landscaping. Noise and privacy berms on the lid park were built with styrofoam to minimize weight on the bridge deck.

The project included an extensive stakeholder and public involvement program including the City of Golden, CDOT, Colorado School of Mines, and Jefferson County. Muller’s success with stakeholder input demonstrates how early and continuing public and agency communication and collaboration achieves consensus and accelerates project delivery.

The City of Golden community connectivity improved in several ways. Colorado School of Mines students now walk from home to class through a park built above US 6, rather than crossing the busy multi-lane highway. The park on the lid above US 6 provides neighbors with quiet seating areas to enjoy mountain views. Cyclists climb 19th Street to Lookout Mountain on bike lanes and wide concrete trails through the park. Finally, the depressed US 6 alignment and low-speed design of 19th Street both serve to minimize noise in the adjacent neighborhoods. Overall, the Linking Lookout project is a shining example of how competing goals can all be achieved in a major transportation project via community involvement and innovative quality design.


City of Golden


Transportation Planning & Design
Traffic Engineering & ITS
Stormwater & Floodplain Management



  • WTS Colorado Innovative Transportation Solution of the Year 2017
  • American Public Works Association (APWA) – Colorado Chapter Project of the Year, Transportation $5M but less than $25M 2018
  • American Association of State Highway and Transportation Officials (AASHTO) America’s Transportation Awards, Best Use of Technology & Innovation, Medium Project 2018
  • Federal Highway Administration Environmental Excellence Award 2019
  • ACEC National Grand Award, Engineering Excellence Awards 2019
  • ACEC Colorado Grand Conceptor Award, Engineering Excellence Awards 2019


47-foot Concrete Box Culvert | 2.5 Miles of Corridor Planning | 16 Curb Ramp Improvements and Upgrades | 1 Mile of Fiber Optic Lines | 1 Interchange | 3 Intersections Designed | 2.5 Miles of Urban Roadway | 1 Roundabout | 2,829 Feet of New Sanitary Sewer Lines | 5,373 Feet of Storm Drains | 0.6 Mile of Mountain Trails| 816 Feet of Water Lines

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