Alaska Builds Second Six-Lane Highway

Mar 28, 2018 | Construction, Engineering, Transportation

Sam Friedman
Freelance writer in Fairbanks

A section of the New Seward Highway between Dowling Road and Dimond Boulevard during the summer 2017 construction season. During 2018, crews plan to complete most of this section of highway. A final wave of Seward Highway widening (from Dimond south to O’Malley Road) is expected to commence in 2021.

Anchorage mega-project in second of three stages

A project to transform Anchorage’s major north-south highway into a six-lane road is almost two-thirds done. This summer, contractor QAP plans to finish construction on the second of three main phases to widen and improve the Seward Highway between Tudor Road and O’Malley Road.

The third stage of the project is now being designed, with plans for construction to start around 2021.

For more than a decade planners have been working on the busy four miles between Tudor and O’Malley, transforming the stretch of roadway into the second six-lane highway in the state.

Key Corridor

As it enters Anchorage from the south, the Seward Highway passes near Dimond Center (Alaska’s largest shopping mall), midtown Anchorage, the University of Alaska Anchorage, and Providence Alaska Medical Center (Alaska’s largest hospital) before ending at 5th Avenue in downtown Anchorage.

The original Seward Highway was built in 1952. The then two-lane highway connected Seward on the Kenai Peninsula with downtown Anchorage, along a path that sometimes parallels the Alaska Railroad tracks. The city of Anchorage itself had grown out of a railroad construction camp established at Ship Creek in 1915.

In 1952, Anchorage had recently overtaken Fairbanks as the largest city in the Territory of Alaska, but Anchorage was a much smaller city than today. Along the Seward Highway corridor, the hospital and university in the Goose Lake area didn’t open until 1962 and 1970, respectively. The Dimond Center, originally a small shopping center, opened in 1977, and the BP high rise that towers over midtown Anchorage wasn’t built until 1985.

Anchorage’s population at the 1950 census was 11,254 and the city hadn’t yet swallowed what is today the neighborhood of Mountain View (which had a 1950 population of 2,880).

The Seward Highway remains a two-lane highway south of Anchorage, the only road from Anchorage to Girdwood, Whittier, and the Kenai Peninsula. Inside urban Anchorage, the original two-lane highway is known is the Old Seward Highway and parallels the path of the current highway.

Construction of the four-lane New Seward Highway was completed in 1971, with a series of interchange expansions occurring over the next two decades. The current highway between south and midtown Anchorage is a modern “controlled access” freeway, which means drivers can only get on and leave it at a limited number of designated entrances and exits.

As of 2016 traffic study, the Seward Highway had busier sections of highway than any other road in Alaska except for the Glenn Highway. The busiest section of the Seward Highway was in midtown just north of 36th Avenue, where average daily traffic was 56,990 vehicles a day. The next busiest section was between Dowling Road and Dimond Boulevard, where traffic averaged 56,837 vehicles per day. For reference, Anchorage’s total population in 2016 was just less than 300,000 people. The busiest highway section of the state, on the Glenn Highway, averaged 65,172 vehicles per day to the east of the Muldoon Road intersection.

A Decade of Planning

Planning to make the Seward Highway a six-lane highway began more than a decade ago with public meetings and an environmental assessment that was written between 2001 and 2007.

The project has three main goals, says Project Manager Sean Baski, PE, with the Alaska Department of Transportation: to improve safety, to improve congestion, and to improve cross corridor connectivity, the flow of traffic on the east-west streets around the highway.

The project adds two main highway bridges that will allow traffic to pass below. One is located where 76th Avenue meets Lore Road on the section of highway under construction this year. Another is where the newly-renamed Scooter Drive will meet Academy Drive under a yet-to-be-built highway bridge. The Scooter/Academy Drive intersection is part of the final third of the project.

The 2007 environmental document for the Seward Highway project covers a large section of highway from 36th Avenue on the north end to Rabbit Creek Road to the south. But the Department of Transportation focused on the middle section, from Tudor Road south to O’Malley Road.

For the southern end of the corridor, the project planners decided the highway didn’t have enough traffic between Rabbit Creek and O’Malley Road to merit widening from four lanes to six.

The northern end of the corridor was wrapped into a different road improvement project called the Midtown Congestion Relief project, which extends north to 20th Avenue.

North of Tudor Road, the Seward Highway transitions from a freeway to a busy arterial city street. This part of the highway is actually the busiest section. According to the project website (, the midtown part of the corridor also has a “long history of unfinished projects that similarly sought to address traffic congestion issues.” Work on the midtown part of the Seward Highway is in a pre-design phase. The next step is a PEL, or planning and environmental linkages, study. An open house to discuss the project was held in January.

Introducing the “Diverging Diamond” and a Street Named for a Cat

The new Seward Highway expansion plans call for a style of interchange that’s relatively new to Alaska, the “diverging diamond.” In this style of interchange, drivers make a figure eight type path, temporarily switching to the left of the oncoming lane as they cross over or under a highway bridge.

The advantage of this intersection style is that it’s easier to make easier left turns onto the highway, because it doesn’t require crossing oncoming traffic. Additionally, it’s a relatively inexpensive interchange that can be built with budget similar to traditional diamond-shaped interchanges and in about the same space.

The first diverging diamond interchange in the United States was built in Springfield, Missouri in 2009. Alaska’s first diverging diamond recently went up where Muldoon Road passes over the Glenn Highway, and drivers have been figuring it out, Baski says.

“The word is things are going well,” he says. “As with any interchange, there are things to learn about it. The thing about diverging diamonds is they’re pretty intuitive. Even though you’re crossing to the other side of the highway, some people don’t even notice they’re doing anything different. You get in the left lane if you want to turn left you get in the right lane if you want to turn right.”

The next section of the Seward Highway project calls for diverging diamonds where the highway crosses over Dimond Boulevard/Abbott Road and where it crosses over O’Malley Road.

The new highway will also feature a new raised section that will allow traffic to pass underneath. South of Dimond Boulevard and north of O’Malley Road is Academy Drive, a street that dead-ends at a Seward Highway access road.

In this section, the Seward Highway separates Independence Park, a large neighborhood, from the Dimond Center shopping mall. There’s not currently a convenient way to cross the highway at this location, but pedestrians found a way despite fences intended to discourage them.

“There are a lot of youth who cross the highway. The state has fences along this stretch and for a long time youth have gone out and clipped all of the fences on that stretch and our maintenance crews have gone out and fixed it,” Baski says. “There’s an obvious need for cross-corridor connectivity on the pedestrian front, getting across the highway. The main attractant is obviously Dimond Center mall.”

When the highway project is complete, both pedestrians and drivers will be able to cross Academy Drive under the highway. On the west side of the highway, a short street previously known as Abbott Road has been renamed because it didn’t connect to Anchorage’s bigger Abbott Road. The new name is Scooter Drive, after a family’s cat that lived on this street.

Instead of diverging diamonds, the new Scooter/Academy interchange will move traffic under the highway with a pair of roundabouts. A similar traffic pattern was built this summer to create more cross corridor connectivity where 76th Avenue and Lore Road meet under the Seward Highway. There is a pair of roundabouts and a new road under the newly-raised highway.

Breaking Ground

Construction on the northern third of the project, from Tudor Road to Dowling Road, was completed in 2013. The second third, between Dowling and Dimond, started in 2017. That section should be substantially completed by the end of the 2018 construction season, Baski says. Some landscaping and finish work may take place in 2019.

To minimize traffic backup during construction during the previous two stages of construction, work crews rebuilt frontage roads along the highway first and then directed traffic down the frontage roads while working on the main stem of the highway, Baski says.

The final third of the project will be more difficult because there’s no frontage road on the west side of the highway, he says. During construction, workers will build a new frontage road on the west side of the Seward Highway from Dimond Boulevard to Scooter Drive, in front of the recently-shuttered Sam’s Club store. There won’t be an access road on the west side of the highway south of Scooter Drive because the area is a residential subdivision which is accessed from the east side, on Old Seward Highway.

The first two construction contracts have gone to QAP, a subsidiary of the French COLAS Group. The design contract for all three stages of the project was won by Colorado engineering firm CH2M, which was purchased by Dallas-based Jacobs Engineering Group in December.

Combined, the total project cost for the three highway sections is expected to be about $280 million. The total project cost includes construction as well as design and the expense of purchasing right-of-way from landowners and relocating utilities like water pipes and electricity wires.

Under a formula common with highway construction projects, the federal government will pay for 90 percent of the cost, with the state covering the remainder. State funding for the final third hasn’t yet been approved.

For additional information, the website for the Seward Highway construction project is The website for the future construction project along the corridor in midtown is


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