Butsick Andrew J, Wood Jonathan S, Jovanis Paul P
Kittelson & Associates, Inc., 610 SWAlder St, Suite 700, Portland, OR 97205, United States.
South Dakota State University, Department of Civil and Environmental Engineering, Crothers Engineering Hall 132, Box 2219, Brookings, SD 57007, United States.
Accid Anal Prev. 2017 Sep;106:223-233. doi: 10.1016/j.aap.2017.06.006. Epub 2017 Jun 20.
The Highway Safety Manual provides multiple methods that can be used to identify sites with promise (SWiPs) for safety improvement. However, most of these methods cannot be used to identify sites with specific problems. Furthermore, given that infrastructure funding is often specified for use related to specific problems/programs, a method for identifying SWiPs related to those programs would be very useful. This research establishes a method for Identifying SWiPs with specific issues. This is accomplished using two safety performance functions (SPFs). This method is applied to identifying SWiPs with geometric design consistency issues. Mixed effects negative binomial regression was used to develop two SPFs using 5 years of crash data and over 8754km of two-lane rural roadway. The first SPF contained typical roadway elements while the second contained additional geometric design consistency parameters. After empirical Bayes adjustments, sites with promise (SWiPs) were identified. The disparity between SWiPs identified by the two SPFs was evident; 40 unique sites were identified by each model out of the top 220 segments. By comparing sites across the two models, candidate road segments can be identified where a lack design consistency may be contributing to an increase in expected crashes. Practitioners can use this method to more effectively identify roadway segments suffering from reduced safety performance due to geometric design inconsistency, with detailed engineering studies of identified sites required to confirm the initial assessment.
《公路安全手册》提供了多种可用于识别有望进行安全改善的地点（SWiP）的方法。然而，这些方法大多无法用于识别存在特定问题的地点。此外，鉴于基础设施资金通常指定用于与特定问题/项目相关的用途，一种用于识别与这些项目相关的SWiP的方法将非常有用。本研究建立了一种识别存在特定问题的SWiP的方法。这是通过使用两个安全性能函数（SPF）来实现的。该方法应用于识别存在几何设计一致性问题的SWiP。使用5年的碰撞数据和超过8754公里的双车道农村道路，采用混合效应负二项回归来开发两个SPF。第一个SPF包含典型的道路元素，而第二个包含额外的几何设计一致性参数。经过经验贝叶斯调整后，识别出了有望进行改善的地点（SWiP）。两个SPF识别出的SWiP之间的差异很明显；在前220个路段中，每个模型都识别出了40个独特的地点。通过比较两个模型中的地点，可以识别出那些设计一致性不足可能导致预期碰撞增加的候选路段。从业人员可以使用这种方法更有效地识别由于几何设计不一致而导致安全性能下降的路段，不过需要对识别出的地点进行详细的工程研究以确认初步评估结果。
