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By Mike McKibbin

Remember when roundabouts were the latest answer to ever-increasing traffic congestion on Colorado highways?

Despite some misgivings, they seem to be an accepted part of traffic engineering, even in big box store parking lots.

Get ready for diverging diamond interchanges, including one at Interstate 70 and Kipling Street in Wheat Ridge. It was one of several transportation-related projects city manager Patrick Goff described in a recent unofficial State of the City address.

According to Wikipedia, diverging diamonds have been used in France since the 1970s and the design was listed by Popular Science magazine as one of the best engineering innovations in 2009. Such interchanges, also called a double crossover diamond interchange, moves traffic on the non-freeway road across to the opposite side on both sides of the highway bridge. That means motorists on the freeway over or underpass briefly drive on the left side of the road. The crossover “X” intersections are usually controlled by traffic lights. Right turn lanes are placed before the crossover intersections.

The Colorado Department of Transportation plans this interchange to be similar to U.S. Highway 36 and McCaslin Boulevard in Louisville. However, Kipling Street would remain under the I-70 bridge.

CDOT described the overall project to include I-70 from Ward Road to Wadsworth Boulevard and 44th Avenue to 51st Place on Kipling Street. The first potential improvements are the eastbound I-70 auxiliary lane from Ward Road to Kipling Street and the westbound I-70 off-ramp with associated changes at 49th and 50th avenues. Other changes are planned to the north and south frontage roads and local area streets, along with an eastbound I-70 auxiliary lane from Ward Road to Kipling Street.

CDOT completed a planning and environmental linkages study in July 2013. A National Environmental Policy Act environmental assessment and preliminary design began in 2016. Leah Langerman, public involvement coordinator in the transportation business unit of David Evans and Associates — a CDOT project contractor — wrote in an email that the environmental assessment is expected to be released for public review and a final public meeting held to gather comments in early 2019, followed by Federal Highway Administration permission to proceed.

The NEPA study will help CDOT and Wheat Ridge pursue funding by showing the need and the specific improvements to address the need, Langerman noted. CDOT has also recommended this project be included on a proposed ballot initiative for transportation funding in the November general election, she added.

In an interview, Goff added the design will require right-of-way purchases from adjacent property owners, which he expected would take some time.

Light Rail This Summer

The much-discussed and long-delayed G Line Ward Station light rail project received Colorado Public Utilities Commission approval in March that allows further testing of the same crossing technology that caused the Regional Transportation District headaches on the A Line to Denver International Airport. Still, Goff said light rail service between Wheat Ridge and Union Station in downtown Denver could begin later this summer.

As part of that effort, a $12 million project includes reconstruction of adjacent streets, a new traffic signal, pedestrian bridge over the light rail tracks, pedestrian access improvements and public amenities, Goff added. Transit-oriented development is envisioned at the station.

“The vision plan includes an outdoor recreation focus since there are a couple of large lakes there and we could maybe develop that into a regional park,” Goff said.

Three residential and commercial projects are also planned, with around 300 townhomes, 200 apartment units and 6,000 to 8,000 square feet of commercial space, he added.

Greenway Project

Goff said a 2011 plan called for a greenway project on West 38th Avenue between Sheridan Avenue and Wadsworth Boulevard. It included temporary road changes from four to three lanes, with turn lanes in the middle in each direction. The goal was to spur more pedestrian and cyclist use of the corridor and new amenities to make it more attractive, Goff added.

“We had a lot of support for it, but we couldn’t get (City Council) to approve the project,” Goff noted. “But it’s still a priority.”

City Council did agree to a small greenway project on land owned by Jefferson County School District R1. A memorandum of understanding between the district and city allows its use for events, Goff said.

“But we need a more official plaza area, something like an informal gathering place with a small amphitheater,” he added.

The city is selecting a design firm and public input will be sought, Goff said.

Since 2011, 38th Avenue has seen much commercial development, such as a new Vectra Bank.

“Some of that is due to the vision that’s in the plan,” Goff said.

Multi-family housing has also been proposed for the corridor. Motorist speed has dropped with the change from four to three lanes, he added, and several annual community events are held along the street.

Funding has not been identified for the project, with initial estimates in the $5 million to $10 million range, depending in part on how many lanes of traffic to permanently allow, Goff said.

Wadsworth Widening

Widening of Wadsworth Boulevard between 35th Avenue and I-70 to six lanes, with a two-way bicycle lane, continuous sidewalks, streetscape improvements and RTD facilities is estimated to cost between $45 million to $60 million. The city has offered a $7 million match to obtain funding from other sources, Goff said. He anticipated the project could start around 2021 and pointed out the lengthy environmental assessment process could delay that timeline, as could protective measures for five identified historic properties in the project area.