236 Transportation Research Record: Journal of the Transportation Research Board, No. 2472, Transportation Research Board of the National Academies, Washington, D.C., 2015, pp. 236–242. DOI: 10.3141/2472-26 Safety on low-volume roads is a major concern. It has been reported that the traffic fatality rate is more than three times higher on rural roads than on other roads. Some of these fatalities occur at intersections, and the safety risks increase when the intersections are skewed or have an eleva- tion difference. In Idaho, some skewed intersections (e.g., those on SH-39 and US-91 in eastern Idaho) are the result of highways having been built parallel to rivers or railroad lines and local roads having been built later on a grid with a north–south or east–west orientation. In an attempt to improve the safety of existing intersections, the Idaho Transporta- tion Department’s District 5 performed a systematic and comprehen- sive evaluation of all of the intersections on the state highway system in southeastern Idaho. In total, 125 intersections along US-91 and 194 intersections along SH-39 were evaluated, and safety improvements were made. These improvements resulted in a reduction in the overall number of crashes along these two highways. This paper presents the results of these evaluations and the recommendations that followed. A recent report by a national transportation research group has high- lighted that the rural and non-Interstate roads and bridges that serve and connect the nation’s rural areas face several significant challenges, including a lack of desirable safety features and a traffic fatality rate far greater than that of any other type of road or highway (1). The report stated that the main reasons for these safety issues were inadequate roadway safety design, longer emergency vehicle response times, and higher travel speeds on rural roads than on urban roads. Some of the low-cost solutions for these problems identified by TRB’s Standing Committee on Low-Volume Roads include chang- ing signage on the basis of crash reports; using cameras to assist in law enforcement; drawing attention to signage with blinking LEDs, reflective striping, and markers surrounding the sign; and using reflector posts on the sides of roads without striping or other markings to guide drivers (2). AASHTO defines intersections as “the general area where two or more highways join or cross, including the roadway and roadside facilities for traffic movements within the area” and gives the main objective of intersection design as facilitating the “convenience, ease, and comfort of people traversing the intersection while enhancing the efficient movement of motor vehicles, buses, trucks, bicycles, and pedestrians” (3). Traffic fatalities are notably higher at inter- sections. In 2008 NHTSA indicated that 56% of the 37,261 fatalities on U.S. roadways occurred in rural areas (4). More than 20% of all traffic fatalities occur at intersections, either with or without signage (5). Souleyrette conducted a safety evaluation of intersections on ultralow-volume roads (fewer than 150 daily entering vehicles) and observed that these roads exhibited much lower crash rates than did local rural roads (6). According to Golembiewski and Chandler, the geometric design of intersections on low-volume roads can create navigational prob- lems for motorists and possibly contribute to crashes at these loca- tions (5). Two important aspects of geometric design—namely, sight distance and skewed geometry—could cause this problem. Inter- section sight distance is typically defined as the distance at which a motorist can see approaching vehicles before his or her line of sight is blocked by an obstruction near the intersection. The driver of a vehicle approaching an intersection or departing from a stopped position at an intersection should have an unobstructed view of the intersection, including any traffic control devices; in addition, there should be sufficient length along the intersecting roadway to permit the driver to anticipate and avoid potential collisions. Poor sight distance can lead to rear-end crashes on the approaches and to angle crashes within the intersection because motorists may be unable to see and react to traffic control devices or approaching vehicles. Skewed intersections intersect at angles less than or equal to 60°. Vehicles traverse longer distances while crossing or turning at these intersections than at regular intersections that intersect at 90°. These longer distances increase the period of exposure to cross traffic and therefore increase the chance of a crash. Another problem with skewed intersections is that drivers have skewed angles for the observation of oncoming traffic and hence find it hard to judge the speed of oncom- ing vehicles. Several other issues related to skewed intersections were listed by Golembiewski and Chandler (5). Golembiewski and Chandler listed three typical approaches to the identification of intersection safety issues: the systematic approach, the spot location approach, and the comprehensive approach that incor- porates human behavior issues (5). For the systematic approach, the analysis is based on crash types and the proven safety countermeasures selected on the basis of those crash types. The spot location approach has typically been based exclusively on an analysis of crash history. The comprehensive approach introduces the concept of the four E’s of safety: engineering, enforcement, education, and emergency medical services. This approach recognizes that not all issues can be addressed solely by infrastructure improvements. Regardless of the implementation approach, a field review should be conducted at iden- tified locations. Intersection field reviews have the potential to identify safety issues and solutions. Field reviews can be conducted as informal Safety Evaluations for Skewed Intersections on Low-Volume Roads Case Study Bhaskar C. S. Chittoori, Mandar Khanal, and Dan Harelson B. C. S. Chittoori and M. Khanal, Department of Civil Engineering, Boise State University, 1910 University Drive, Boise, ID 83725-2060. D. Harelson, Idaho Transportation Department, P.O. Box 7129, Boise, ID 83707. Corresponding author: B. C. S. Chittoori, bhaskarchittoori@boisestate.edu.