ADOT’s plan to fix landslide on Highway 89 near Page

On February 23, 2013, a large landslide occurred on Highway 89 about 25 miles south of Page, Arizona. The Arizona Department of Transportation (ADOT) closed the highway and has been studying how to fix it. Currently, to get from Bitter Springs to Page requires a 45-mile detour (see map here).   For more background, see my post here which links to some updates and a video.

The Highway was originally built over a portion of ancient landslide as shown in the photo below (annotated by Wayne Ranney), rocks slid from the red line to the yellow line:

89-slump

The next photo, ADOT Figure 1 from a 463-page geotechnical report shows the condition of the highway just after the February slide. Displacements in the pavement are up to six feet vertically. The active landslide is approximately 135 feet below the roadway and measures approximately 1,200 long at the base of the slope. It took out about 150 feet of road.

89-landslide-collapsed-ADOT

ADOT figure 6 shows an annotated cross-section.  The February slide is the small red arc on the left side of the photo.

89-landslide-annotated-section-ADOT

The fix recommended by ADOT (see press release) is to “move the road 60 feet [east], and take the rock from the cut and put it at the base of the hill to form a rock buttress to lock in the recent slide.” “The right-of-way and environmental process will be our biggest challenge, but we will streamline that as much as possible so we can benefit the traveling public and especially the Bitter Springs and Marble Canyon communities.”

The repairs will cost about $40 million and take more than two years to complete.  Meanwhile, ADOT is paving  Navajo Route 20 which parallels Highway 89 to the east to establish a shorter detour route for motorists until repairs are complete on US 89. Money for this comes from a $35 million federal grant.  “Construction started in late May on N20 and is scheduled to be completed in August.”

ADOT has a dedicated webpage for this project at http://www.azdot.gov/us89/ to keep us informed.

Highway 89 is the main route from Flagstaff to Lake Powell and Utah. An editorial in Flagstaff’s Arizona Daily Sun (reprinted in the Arizona Daily Star) asks why bother to fix Highway 89 when the alternate route, Navajo 20 is being improved. Why indeed. Why spend $40 million on a fix of Highway 89 that will take it over a geologically unstable landslide, when a reasonable, though less scenic, alternative is available? See map below:

89-road-map

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