The Arizona Department of Transportation (ADOT) has an extensive video library that documents its work and the dedication of its personnel from around the state. In paving a 28-mile stretch of Temporary US89 (also known as US 89T and Navajo Route 20), ADOT encountered significantly sandy soils that led to multiple vehicles getting stuck. As the video above notes, water trucks, pick up trucks, paving equipment, etc. all were stuck at some point along the way. What the video does not quite reveal is one of the main solutions ADOT found: utilization of geogrid reinforcement.
Triaxial geogrid from Tensar helped save approximately $2 million dollars for ADOT on the construction of Navajo Route 20 and completed the key phase document in the video ahead of schedule.
ADOT’s Tribal Transportation website include additional information about the project, including a Q&A document that notes the need for geogrid reinforcement:
ADOT is installing geogrid on top of the sand [to] help create a stable base which will be weighed down by the aggregate base and asphalt to stabilize the roadway
The US89T / Navajo Route 20 work has been essential to reopen connections in northern Arizona following the 20 February 2013 landslide that closed a section of US 89 between Bitter Springs and Page. After the reconstruction of US 89 is complete (~ mid-2014), US 89T will be returned to the Bureau of Indian Affairs and will be referred to again as Navajo Route 20, with maintenance handled by the Navajo Division of Transportation.
See also: “US 89 (Navajo Route 20) bypass fully open with no restrictions” (15 October 2013)
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LOOKING BEYOND LANDSLIDES
Landslides and other geohazards are an increasing concern, and there remains a lack of standardization in response (materials, engineering methodology, etc.) in North America, and particularly in the United States. A new professional society has formed–Association of Geohazard Professionals–to help address this void between the geotechnical engineering field and state and federal transportation officials.
