Assessing the applicability of the highway safety manual to gravel roads: A case study of Wyoming

Factors Contributing to Crashes on Low-Volume Unpaved Roads

“…Vehicle tires may not have the traction needed to provide stable control on loose gravel, making driving harder than on paved roads ( 4 ). Moreover, dust generated from surface materials may reduce visibility ( 5 ). Intersections and curves where turning and braking are required create different safety-related issues such as sliding out of control ( 6 ).…”

“…Intersections and curves where turning and braking are required create different safety-related issues such as sliding out of control ( 6 ). Other safety-related problems include narrow traveled ways, odd horizontal and vertical profiles, a limited clear zone on the roadside to aid recovery when veering off the road, inadequate warning signs, and lack of law enforcement ( 5 ).…”

Literature Review on Gravel Road Maintenance: Current State and Directions for Future Research

“…In contrast, unpaved roads are unsealed (unsurfaced) roads, including dirt, earth, and gravel roads, as defined in the gravel roads management report by Huntington and Ksaibati (2). According to the second edition of the American Association of State Highway and Transportation Officials (AASHTO) low-volume road design guidelines (3), unpaved roads satisfy the criteria of low-volume roads if the average daily traffic volume is 2000 vehicles per day or less (3,4).Gravel roads play a critical role in agriculture, forestry, wildlife and tourism, fire control, search and rescue services, recreation, and cultural and historical heritage, and affect socioeconomic living conditions in rural areas (5, 6), and therefore should be maintained at an…”

“…In contrast, unpaved roads are unsealed (unsurfaced) roads, including dirt, earth, and gravel roads, as defined in the gravel roads management report by Huntington and Ksaibati ( 2 ). According to the second edition of the American Association of State Highway and Transportation Officials (AASHTO) low-volume road design guidelines ( 3 ), unpaved roads satisfy the criteria of low-volume roads if the average daily traffic volume is 2000 vehicles per day or less ( 3 , 4 ).…”

“…According to Apronti et al ( 9 ), around 69% of the road mileage in the U.S.A. consists of low-volume roads and taking traffic counts on such roads is not cost-effective. About 35% of the public road network in the U.S.A. is unpaved ( 4 ), which implies that 34% of paved roads in the U.S.A. are low-volume roads, that is, the average daily traffic volume is 2000 vehicles per day or less, based on the new second edition of the AASHTO low-volume road design guidelines. Similar figures, that is, 35%, are reported for the unpaved road network of Sweden ( 10 ).…”