A rock slide that temporarily closed the Seward Highway Monday came as a surprise to officials with the Alaska Department of Transportation and Public Facilities, which had recently taken steps to prevent such slides in the Mile 113 area of the highway after a similar incident earlier this year.
The latest rock slide was reported around 8 a.m. Monday and stopped traffic between the Potter Marsh weigh station and McHugh Creek. DOT spokesperson Shannon McCarthy said this slide came down at the "exact same" location another rock slide that closed the highway on Feb. 19.
The DOT scraped the area in May in an attempt to "try and get anything loose off," McCarthy said, which made Monday's slide unexpected.
Four natural occurrences are common causes of rock slides: rain, wind, the freeze-thaw cycle, and earthquakes. Because of this, autumn is the most common time for rock slides on the Seward Highway.
Monday morning saw a little more than a quarter-inch of rain observed and average wind gusts blowing 11 mph in nearby Anchorage, the National Weather Service said. David Kramer, a forecaster with the service in Anchorage, said about a half-inch of rain was recorded at the NWS monitoring station on Sand Lake Road over the weekend.
The Anchorage area has seen measurable precipitation during each of the last seven days.
"We've had multiple systems bringing in rain over a period of time," Kramer said. "None of them have been particularly record-breaking."
February's slide came in the midst of unusual freeze-thaw weather, with temperatures dropping into the mid-20s after reaching a record-breaking 44 degrees.
According to McCarthy, February's slide was the first time DOT had an issue with a rock slide in that location. In 2012, a woman was seriously injured less than 1 mile away by falling ice. Last spring, the Alaska Legislature appropriated a $4.8 million settlement with the woman.
Neither of the rock slides this year caused injury, but both shut down portions of the highway.
McCarthy said Monday's rock slide only stopped traffic for about an hour, which she added was a "quick turnaround."
According to McCarthy, DOT crews were already on the highway doing work in an effort to keep the ditches clear so falling rock doesn't hit debris in the ditch and bounce onto the highway.
A law enforcement officer from the National Oceanographic and Atmospheric Administration who was first on the scene provided traffic control, with police and DOT crews also responding.
By 9:45 a.m. Monday, traffic was freely flowing in both directions on the Seward, with one boulder pushed to the north side of the highway and a second resting on a guardrail above the Alaska Railroad tracks and Turnagain Arm. DOT workers removed the guardrail boulder later Monday, with a railroad official on hand to ensure the tracks weren't obstructed by the work.
McCarthy said the Seward Highway is monitored daily for safety hazards and there are about six projects in the works through the Highway Safety Improvement Program, a project to mitigate falling rocks from the weigh station to Indian.
Alaska Dispatch News photographer Bill Roth contributed to this story.
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