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Unusual Muldoon interchange design prompts public outreach campaign

  • Author: Devin Kelly
  • Updated: September 28, 2016
  • Published May 30, 2015

State transportation officials have begun the process of convincing the public that a proposed northeast Anchorage interchange that would move drivers to the "wrong" side of the road is not as confounding as it looks.

A virtual video tour, social media posts and even a 30-second, movie-theater-style "preview" are among the tools that the Alaska Department of Transportation and Public Facilities will be using to educate people about plans for a "diverging diamond" interchange where Muldoon Road passes over the Glenn Highway. Aimed at reducing congestion and improving safety, the $55 million interchange would incorporate crisscrossing one-way lanes with traffic signals and free-flowing ramps, as well as a new pedestrian walkway.

Contrary to what's standard in the U.S. and most other countries, drivers would cross to the left side of the overpass and move on that side for about 500 feet in the interchange.

Project manager Steve Noble of DOWL-HKM said at a media briefing Wednesday that the design, a first for Alaska, is cheaper, safer and more efficient than other alternatives analyzed by engineers and in public meetings.

"In the end, it was a very clear choice for us," Noble said. He said construction could start as soon as next spring.

The current Muldoon Road-Glenn Highway interchange is more than 40 years old. In the early 2000s, traffic volumes exceeded the capacity of the intersection and there's been congestion ever since, Noble said.

Traffic increased with the 2008 opening of the Tikahtnu Commons shopping center, adding to an area that already includes an entrance to Joint Base Elmendorf-Richardson and Bartlett High School. Pedestrian safety has become an increasing concern, with people occasionally cutting through traffic to avoid a circuitous walkway. The overpass is also too low for some trucks, officials said.

From a concept pioneered in Versailles, France, several dozen "diverging-diamond" designs have been deployed in the United States since 2009, including in Utah and Missouri. For the Muldoon Road-Glenn Highway interchange, the design allows for free-flowing right and left ramp movements, so cars no longer have to pause and wait for gaps in oncoming traffic to merge on and off the road, Noble said.

Noble also said a study found the project would cost about $10 million less to build and would last longer than other alternatives. DOT commissioner Marc Luikens and regional director Rob Campbell support the outcome of the study, said DOT spokeswoman Jill Reese.

Like roundabouts in recent decades, diverging-diamond designs have generated considerable excitement among engineers as a different approach to traffic planning. But, like roundabouts, officials acknowledge the big challenge is getting the public used to them.

Skepticism abounded on the project's Facebook page as the department advertised a third public meeting on Wednesday. One person called the design "over-engineered." Others said it looked too confusing.

Those sentiments will be the target of the public awareness campaign. The state transportation department doesn't typically produce videos but has already made two, one of which is a virtual animated tour showing how traffic patterns would work with the new interchange.

The second, a 30-second video, is set to play this fall during the previews at theaters at Tikahtnu Commons. It starts off with the text, "Coming soon to an interchange near you."

In a deep voice, a narrator says, "In a world just like ours … they cross to the opposite side of the road."

Noble said the project managers are taking cues from Utah, which has built at least six diverging-diamond interchanges. Utah officials stressed that public outreach was critical for such an unusual design, he said.

He also said feedback to federal highway officials on diverging-diamond designs has been generally more positive than for roundabouts.

"People are finding it's not nearly as confusing as they thought it would be," Noble said.

With the intersection design approaching completion, project managers said they're on track to put out bid documents this fall. It has been only about two years since planning started, and the relatively speedy timeline underscores safety concerns surrounding the intersection, said Tom Schmid, project manager with the DOT.

Noble said one big selling point for the diverging diamond came when engineers estimated it would cost $10 million less to build, because engineers won't have to build a temporary bridge before tearing down the old overpass. A mix of state and federal funding will finance the project, Schmid said, though officials are looking to draw mostly from federal sources.

Officials have held three public open houses on the project. There will be further public involvement once the contractor is selected, Noble said.

To submit comments or find other information relating to the project, visit

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