Operational Safety of Gravel Roads in Rural and Tribal Communities: Vulnerability to Structural Failures and GeoHazards

Abstract

Of the 4.1 million miles of federal and state highways in the U.S., 2.2 million miles (or 54%) are unpaved, gravel roads. In the Pacific Northwest and Alaska, unpaved gravel roads provide critical transportation access, with some communities relying on just a single highway for access into and out of town. In such cases, these highways become a critical component of the infrastructure, and there is a need to ensure that safe access is always available to the communities. The Idaho highway database has been used to identify unpaved, gravel roads in Idaho that are critical for access to rural communities. Once identified, information regarding their existing condition has been used to assess their vulnerability and other impacts. The results of this study are considered an initial evaluation that relies on information that is readily available in the database. The project outcomes include a comprehensive literature review of unpaved roads including data produced from field visits. In addition, a questionnaire survey was sent to local jurisdictions authorities for investigating locations, reasons of road closures, and population size of the affected communities. Finally, 37 responses have been received by the research team indicating five rural communities that have experienced closures and isolation. The reasons for the closure of the unpaved roads were due to the lack of funding for snow removal, excessive dirt, unstable gravel roads, tornados, and heavy rains. The location of those communities was spread across the state of Idaho with corresponding populations range from 25 to 8,500 people.