What you need to know:
- Travelers faced few delays Wednesday as construction crews closed highway lanes and funneled all Glenn Highway traffic in and out of Mat-Su into three lanes on the southbound span of the Knik River Bridge.
- The northbound Knik River bridge span will remain closed for at least 30 days for deck restoration and joint replacement. The southbound span will undergo similar upgrades later this year.
- Several ramps near the bridge are also closed during construction. Officials urge drivers to use the zipper merge technique and stay alert in the work zone.
PALMER - It was smooth sailing over the Knik River bridge Wednesday as thousands of Glenn Highway commuters traveling in and out of Mat-Su faced the first day of a months-long construction project that funnels all vehicles onto one span of the bridge.
Drivers heading north into Mat-Su Wednesday evening saw slight slowdowns between 5 and 6 p.m. as traffic moved into a narrow detour that snakes from the closed northbound highway onto the southbound span.
Morning commuters also reported no significant delays, with speeds reduced to 45 miles per hour through the construction zone.
The northbound span of the Knik River bridge between Mile 30 and Mile 31 will remain closed for at least 30 days while crews restore the deck and replace the joints that connect the bridge to the highway, according to state construction plans.
A detour will siphon all traffic into three narrow lanes on the southbound span for the duration of the closure, with two lanes traveling in one direction and one in the other, officials said.
Crews will use a special barrier-moving machine to shift that configuration twice a day during the work week – at about 3 a.m. and 11 a.m. – to provide double lanes for the direction with the heaviest traffic, state transportation officials said Tuesday.
The span will be reconfigured only once a day on weekends, with the span offering two northbound lanes on Saturdays and two southbound lanes on Sundays, according to the project website.
When construction on the northbound span is complete, the southbound side will undergo a similar closure, with all traffic diverted to the newly reopened side, according to construction plans.
About 31,400 vehicles cross the decades-old bridge each day, according to state traffic data.
Construction crews officially kicked off the closures early Wednesday, completely blocking off the northbound bridge span and shifting all traffic into southbound span lanes set earlier in the week.
The barrier-moving Road Zipper machine brought in state by the project's contractor crawled the open southbound span for about 20 minutes just before noon Wednesday, moving the concrete dividers to allow two lanes for Mat-Su-bound vehicles throughout the afternoon and evening.
The $20 million federally funded project is the first such overhaul for both bridge spans. The northbound side was built in 1965 when the highway was first constructed over the Palmer Hay Flats. The southbound span was added in 1990.
The construction project also brings a series of related ramp closures near the bridges.
The northbound on-ramp from the Old Glenn Highway that enters the Glenn Highway just before the bridge will be closed for the duration of the construction, officials said.
