'No getting on that bridge': Glenn Highway bridge closures, detours to cause major delays

What you need to know:

• The northbound span of the Knik River bridge on the Glenn Highway will close for at least 30 days starting next month for resurfacing and joint replacement, followed by a similar closure of the southbound span.
• All traffic will be diverted to the open span during the closures, with three lanes reconfigured twice daily to accommodate peak-direction flow. Significant delays are expected, and commuters are urged to telework or carpool.
• The federally funded project addresses long-standing issues such as deep rutting. Similar work is planned for the Peters Creek bridge next year.

PALMER – A bridge used daily by thousands of drivers headed into Mat-Su will close for repairs next month as part of Glenn Highway construction expected to trigger major traffic slowdowns and delays into the summer.

The northbound span of the Knik River bridge between Mile 30 and 31 on the Glenn Highway will close for at least 30 days while crews resurface the deck and replace joints connecting the bridge to the roadway, officials said in a statement this week. Work is expected to start by mid-April, although that date could shift due to weather, they said.

Officials plan to divert all traffic onto the southbound span, where a trio of lanes will be reconfigured twice a day to provide two lanes of travel for the direction with the heaviest traffic, they said.

When the northbound work is complete, the southbound side will undergo a similar closure, with all traffic diverted to the newly reopened side, officials said.

Drivers should expect significant backups and delays, especially during peak commuting hours, they said.

About 31,400 vehicles cross the decades-old bridge spans each day, according to state traffic data. Commuters are encouraged to telework or carpool to reduce traffic during the project, officials said.

“There’s just no getting on that bridge during construction,” project engineer Brendan Daugherty said during an interview earlier this year. “This is the least impactful way to do it — everybody on one side of the bridge.”

The bridges are notorious among users for their deep rutting, slick surfaces and frequent low visibility caused by frigid winter ice fog that hangs over the river and contributes to traffic accidents. The construction is designed to address some of those issues, officials said.

There have been about 90 crashes in the miles on or near the Knik River bridges since 2018, according to Alaska State Troopers data, including a 37-vehicle collision that shut down the highway for hours early last year.

Increasing the number of lanes from two to three during the closures is intended to provide some construction congestion relief, officials said during a January transportation fair highlighting the project. But it also means all vehicles on the open span will have to navigate a narrow corridor with little room for error, they said.

Each 1,532-foot bridge span currently holds two 12-foot travel lanes, with a 4-foot shoulder on one side and a 10-foot shoulder on the other, according to a state Department of Transportation fact sheet.

The conversion to three lanes will reduce the width of each by a foot while also significantly shrinking the shoulders to 2 feet on one side and 1 foot on the other, the fact sheet states.

Opposing traffic will be separated by a 2-foot-wide series of concrete barriers, which will be shifted twice daily by a specialty Road Zipper machine rented by contractor Hamilton Construction as a part of the project. The machine is the first of its kind in the state.

Drivers can avoid the construction entirely by traveling the Old Glenn Highway through Butte, but state transportation officials do not plan to designate that route as an official detour because it is too out of the way and not designed to handle high traffic volumes.

While officials plan to reopen the bridge to drivers by mid-summer, construction is not expected to be fully completed until just before the Alaska State Fair in August, they said.

The northbound span of the Knik River bridge was built in 1965, and the southbound span opened in 1990. The overhauls are the first of their kind for both spans, officials said.

The $20 million project will be paid for with federal funds and includes similar work slated for the Peters Creek bridge next year, officials said.

-- Contact Amy Bushatz at contact@matsusentinel.com

This story was updated March 20 to reflect that Hamilton Construction is renting the barrier moving machine.