Crashes are random events and consequently, can occur at any location along the roadway. On roadways with higher traffic volumes, the more frequent occurrence of crashes allows for the direct identification of high crash locations using historical data. However, on local roads, crash occurrence, particularly fatal and serious injury crashes, is less frequent. This makes it difficult to identify trends and treat hazardous sites based on historical data. Geometric, traffic and other features may lend themselves toward crashes potentially happening in spot locations. Therefore, an approach to identifying these types of risk factors on low volume roads is necessary. It is imperative to identify, develop and deliver such approaches for low-volume roads, both those operated by the Oregon Department of Transportation and local agencies (for example, counties), in order to reduce the number and severity of highway crashes and improve highway safety. In essence, the identification of such features and sites is a proactive approach to identifying locations where potential safety issues may exist but no/few crashes may have occurred to date. In identifying such sites, low cost safety countermeasures could then be applied, either at a limited number of locations or on a systemic basis, depending on identified concerns and needs as well as available budget. This proactive approach can prevent or reduce the severity of crashes without waiting for a critical mass of such crashes to occur prior to identifying improvement locations. In many cases, the improvements that can be made are low cost, which creates an opportunity to produce substantial benefits for a relatively small investment. As a result, safety is improved on roadways that are often given lower priority or consideration given the traffic volumes they serve. There is a need to better understand the different risks associated with factors and features along low- and moderate-volume roadways. In understanding where risks are present in the system, a proactive or reactive approach may be employed to make improvements that can translate into reduced (or prevented) crashes in the future. To an extent, such an approach would be similar to a Road Safety Audit (RSA) in that it seeks to identify potential safety issues before they contribute to crashes or based on the occurrence of a significant number of crashes at a location. In Oregon, RSA are used as a reactive tool for crashes. RSAs are limited in that they typically focus on one roadway segment of a finite length due to time, cost and labor constraints and require field site visits. Consequently, similar features or factors that can contribute to crashes along other segments can typically go unidentified. As a result, the systemic implementation of an improvement to address those features or factors is not achieved. Six major tasks have been completed to address these needs including 1) conducting a Literature Review to understand existing approaches and previously identified risk factors and features, 2) Collecting Data for a large sample of Oregon’s low-volume roads, 3) performing Data Analysis to understand what features may influence crash risk, 4) Developing a Risk Index that provides a means to quantify crash risk based on roadway and traffic characteristics, 5) investigating Economic Feasibility to determine which low-cost safety measures may be the best use of the agency safety improvement funds, and 6) performing Case Studies to illustrate how the risk index can be used with real-world data from samples of Oregon’s low-volume roads. The chapters in this publication will detail each of these tasks and the findings and results produced with each effort. (Author/publisher)
Abstract