Update 6 a.m. Thursday: State road workers escorted a pair of convoys Wednesday night through the Anton Anderson Memorial Tunnel to Whittier and are planning another pair on Thursday.
The Alaska Department of Transportation and Public Facilities' Facebook page said the Wednesday convoys — one in each direction — were between 6 p.m. and 7 p.m.
"We anticipate another escort Thursday," DOT officials wrote. "This time is only an estimate and we ask the public to be prepared for the schedule to change."
Crews will begin work Wednesday to repair a rockfall that closed the road-and-rail tunnel to Whittier for routine travel "until further notice," though state officials hope to briefly allow traffic to and from the Prince William Sound town later in the day.
The Anton Anderson Memorial Tunnel was closed at about 1 p.m. Tuesday after rocks came down overnight, according to the state Department of Transportation and Public Facilities.
DOT spokeswoman Shannon McCarthy said Wednesday that the fallen rocks, about 4 feet across, landed on the roadside near a junction box.
"They actually didn't even enter the roadway," McCarthy said. "They're not very large but they're about 500 pounds each."
State workers and geologists called to assess the area within the 2 1/2-mile tunnel where the boulders fell found a section of rock that had "calved off" the wall. McCarthy said the discovery hasn't prompted greater concerns about the overall stability of the tunnel.
"It's about 12 feet tall, 4 to 5 feet wide and 1 to 2 feet thick — it's an estimated 10 tons," McCarthy said. "The rock is a natural formation, so like any other rock it will have seams in it, it will have fissures in it."
The state contracted with Advanced Blasting, a demolition firm that also specializes in rock stabilization. McCarthy said the repair plan calls for sinking nine 12-foot rock bolts into the tunnel wall, then using them to secure rock mesh to prevent further rockfalls. No explosives will be used.
"The crew will be on site and starting to work at about 2 p.m. today," McCarthy said. "They'll be working 24/7 until the work is complete."
No regular traffic will be allowed through the tunnel through Thursday, but once initial stabilization work is finished the state hopes to allow one piloted convoy of road traffic through the tunnel in each direction Wednesday evening.
A post on DOTPF's Facebook page says a vehicle escort into and out of Whittier will happen between 6 and 7 p.m. Wednesday. Another escort is planned for Thursday, but the transportation department warned the time frame could change. Updates can be found on the Facebook page and the tunnel's website.
The Alaska Marine Highway System has adjusted the ferry Fairweather's Thursday round-trip itinerary from Cordova to Valdez, canceling its planned stop in Whittier. Staff are contacting affected passengers, and details on the revised schedule can be found on the system's website.
Dave Schofield, director of Whittier's Department of Public Safety, said Wednesday afternoon that no major issues as a result of the tunnel closure had been reported in Whittier. Two Whittier police officers kept out of town by the closure remained in Girdwood, under a contract to provide policing services there that began Saturday.
"I hope they brought their bathing suit, because they're staying at Alyeska," Schofield said.