Abstract

For increased accuracy of the results of the procedures in the Highway Safety Manual (HSM), states are encouraged to develop jurisdiction-specific safety performance functions (SPF), if necessary. After performing calibration of four-lane divided rural-multilane segments using the HSM methodology, underprediction was observed for total crashes and overprediction was identified for fatal and injury crashes, indicating a need to examine the development of local SPF for Kansas conditions. Accordingly, negative binomial regression was applied to obtain the most suitable model for local conditions. Several additional variables were considered and tested in the new SPFs, which were run through validation set of locations to confirm accuracy. The newly developed SPFs were also compared to the HSM-given SPF and adjusted SPF using statistical parameters such as mean prediction bias, mean absolute deviation, and mean squared prediction error, leading to the conclusion that the newly developed Kansas-specific SPF for four-lane divided rural highway segments reliably predicts total crashes and fatal and injury crashes in rural Kansas. The Kansas-specific SPFs are capable of more accurately predicting total crashes and fatal and injury crashes on multilane segments compared to the HSM and the modified HSM models.

摘要

为了提高《公路安全手册》（HSM）中程序结果的准确性），鼓励各州在必要时开发特定于辖区的安全绩效功能（SPF）。在使用HSM方法对四车道划分的农村多车道段进行校准后，观察到总碰撞事故的预测不足，而致命和伤害事故的预测则被高估，这表明有必要检查堪萨斯州当地SPF的发展情况。因此，应用负二项式回归来获得最适合当地条件的模型。在新的SPF中考虑并测试了其他几个变量，这些变量通过位置验证集进行运行以确认准确性。新开发的SPF也与HSM进行了比较SPF和调整后的SPF使用平均预测偏差，平均绝对偏差和均方预测误差等统计参数得出的结论是，得出的结论是，针对四车道划分的农村公路段的最新堪萨斯州特定SPF能够可靠地预测总车祸和堪萨斯州农村地区发生致命伤亡事故。与HSM和修改后的HSM模型相比，特定于堪萨斯州的SPF能够更准确地预测多车道段的总坠毁以及致命和伤害坠毁。