Fallen rock discovered inside the Anton Anderson Memorial Tunnel closed the only road access to and from the Southcentral Alaska town of Whittier on Tuesday afternoon.
The tunnel was closed at 1 p.m. Tuesday "due to a rock fall hazard inside the tunnel," the Alaska Department of Transportation and Public Facilities said in a news release. It is closed until further notice.
The rocks came down overnight and were discovered Tuesday morning, said DOT spokesman Jeremy Woodrow. He said those rocks were cleared, and the tunnel was briefly reopened Tuesday morning, "until we had a better opportunity to evaluate the area."
"We decided to close it out of an abundance of caution," he said.
DOT staff "are currently evaluating the condition of existing rock inside the tunnel," the department reported.
There was no damage to any vehicles, and no one was harmed in the incident. The tunnel is closed to traffic from 10:45 p.m. to 7 a.m. during the winter months.
"This is rare," Woodrow said of rock falling inside the tunnel. "The last time it happened was close to when it opened, in the early 2000s."
He said the department doesn't know the exact cause of the rockfall, and is waiting on a geologist to deliver more information.
"This is a time of year when we get a lot of freeze and thaw events. You get expansion and contraction, and that can lead to rocks becoming loose," Woodrow said.
Mike Bender, captain and owner at Lazy Otter Charters, said the closure didn't affect his boat taxi and touring business Tuesday, but he's concerned for a couple trips scheduled in and out of Whittier on Wednesday.
"Hopefully, it'll reopen tonight or early in the morning," he said. On Wednesday, his company is slated to boat several people out to a forest service cabin, and pick up a handful of others and bring them back to Whittier.
Joe Shen owns the Anchor Inn in Whittier, and said business Tuesday was much busier than usual for late October as people scrambled for rooms.
"There's quite a few people stuck here. Business-wise, it's helping me," he said. "This time of year, it's usually slower."
The tunnel will also be closed for at least part of Wednesday for semiannual emergency response training, the Transportation Department said on its website. That closure is unrelated to Tuesday's shutdown.
The $80 million tunnel, with walls and ceiling of exposed rock visible throughout the 2.5-mile journey from one end to the other, opened in 2000. It's the longest railroad-highway tunnel in North America, according to the DOT website.