Construction Report: Richardson Highway washout - causes and fixes

FAIRBANKS, Alaska (KTVF) - On Monday, July 11th, a portion of the Richardson Highway washed out near milepost 233 south of Delta Junction.

According to Kaitlin Williams, Publications Specialist with the Alaska Department of Transportation and Public Facilities (DOT), in the event of a washout, “What’s actually happening is the road around the bridge, or the transition from the road to the bridge, that’s what’s washing out. So the road around the bridge washes out, and then you have the bridge sitting there alone.”

In the case of mile 233, a combination of heavy rain and steep inclines in the surrounding landscape led to the washout. “The sediment runs off the mountains, and what it doe, is it fans out, and then it fills up the streams, and then the streams divert around the sediment,” Williams said.

This diversion takes the streams to unplanned places, she explained. “They go, not under the bridge, they start to go around the bridge and then that causes that washout around the bridge.”

To repair a washed out portion of the road, the embankments must be fortified “so that there’s not as much erosion,” Williams continued. “We’re channeling, rechanneling, rerouting the creeks so that they flow under the bridge where they should be going.”

The heavy rain of recent weeks affected 13 other spots in the area as well, all of which need some work. Williams said, “We have a lot of space to cover, a lot of damages to assess, and as the water levels come down, we’re seeing damage we didn’t see before.”

The emergency repairs to the road are expected to cost around $3 million, with permanent repairs coming later.

According to the Department of Transportation, work on the Richardson could last the rest of the season. “Having the Richardson Highway wash out for a week doesn’t happen often, thankfully,” Williams explained.

For now, the road is open, with one-lane traffic in the area and pilot cars running 24/7. Drivers should expect 30 minute delays.

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