a Department of Civil Engineering, Kansas State University , Manhattan , KS , USA.
Int J Inj Contr Saf Promot. 2019 Sep;26(3):251-259. doi: 10.1080/17457300.2019.1621351. Epub 2019 Jun 3.
The Safety Performance Functions (SPFs) in the Highway Safety Manual (HSM) are statistical formulas developed based on limited data gathered from selected few states. Therefore, the HSM recommends calibrating the HSM-default SPFs to local conditions or developing local SPFs to enhance the accuracy of crash prediction. This paper demonstrates the HSM calibration procedure for freeway segments and the quality assessment of the calibration process using Kansas freeway geometric and crash data. A minimum sample size of 446 freeway segments was calculated corresponding to 95% confidence level and 5% error; consequently, data for 521 freeway segments were collected and utilized in this freeway calibration. Results indicated that the HSM methodology overpredicts fatal and injury crashes and underpredicts property damage only crashes for freeway segments in Kansas. Results of quality assessment of the calibration process showed that estimated calibration factors were satisfactory for all freeway types considered in this study.
《公路安全手册》（HSM）中的安全绩效函数（SPF）是基于从少数选定州收集的有限数据开发的统计公式。因此，HSM 建议根据当地条件校准 HSM 默认的 SPF 或开发本地 SPF，以提高碰撞预测的准确性。本文展示了高速公路路段的 HSM 校准程序以及使用堪萨斯州高速公路几何和碰撞数据对校准过程的质量评估。根据 95%的置信水平和 5%的误差，计算出对应于 446 个高速公路段的最小样本量；因此，收集并使用了 521 个高速公路段的数据进行本次高速公路校准。结果表明，对于堪萨斯州的高速公路路段，HSM 方法对致命和受伤事故的预测过高，对仅财产损失事故的预测过低。校准过程质量评估的结果表明，对于本研究中考虑的所有高速公路类型，估计的校准系数都是令人满意的。
