ANCHORAGE, Alaska (Reuters) - A big rig hauling a load too tall to clear an underpass rammed the structure with such force that authorities had to close a major Alaska highway for repairs, causing a disruption rarely seen in the state’s largest city - traffic gridlock.

The accident occurred Wednesday afternoon about 13 miles from central Anchorage on the Glenn Highway, the only road north out of the city and a route traveled by some 57,000 motorists a day, many commuting between downtown and outlying communities of Eagle River, Wasilla and beyond.

The crash of the too-tall tractor-trailer into the bottom of the bridge created an instant bottleneck that snarled traffic and disrupted school and government office schedules in a transportation calamity locals have dubbed “Bridgepocalypse.”

The consequences were fully felt during Thursday’s morning rush-hour. Highway traffic was detoured onto smaller community streets in Eagle River and alternative highway exit and entrance ramps, extending what is normally about a 20- or 30-minute commute by up to five hours.

Schools delayed openings and the Anchorage School District canceled classes in Eagle River for Friday. State workers impacted by the road closure also were advised to stay home on Friday.

Damage from the crash, and resulting shutdown, was limited to the highway’s southbound lanes, so northbound traffic was unaffected - with the caveat that anyone heading out of town was prevented from immediately coming back.

The closure is expected to last through Monday, said Shannon McCarthy, a state transportation department spokeswoman.

“What we don’t want is that span falling on commuters, or even part of it, because it’s like 200,000 pounds,” she said.

The agency was seeking $1.8 million in emergency funding to pull down and replace the damaged span, which McCarthy described as “pulverized.”

In the meantime, Anchorage residents idled or slowed down by the disruption did their best to make light of the ordeal.

Bystanders waved signs, including one woman in a dinosaur suit who held a sign saying: “You’re almost there.”

Entrepreneurs hawked T-shirts proclaiming: “I survived the Bridgepocalypse.” Local kids set up a “Bridgepocalypse” hot cocoa and tea stand.

On Facebook, one commuter likened the experience to being lost in space.

“Captain’s log hour 2.5: Bladder filling. Food supply scarce. Caffeine supply empty. Slowly losing will to live. Good luck and Godspeed fellow travelers,” said a post by commuter Ryan Kelly.