SWOV - Institute for Road Safety Research, P.O. Box 1090, Postcode 2260 BB Leidschendam, Netherlands.
Delft University of Technology, Civil Engineering and Geosciences, The Netherlands.
J Safety Res. 2014 Jun;49:121-7. doi: 10.1016/j.jsr.2014.03.003. Epub 2014 Apr 24.
About 50% of all road traffic fatalities and 30% of all traffic injuries in the Netherlands take place on rural roads with a speed limit of 80 km/h. About 50% of these crashes are run-off-road (ROR) crashes. To reduce the number of crashes on this road type, attention should be put on improving the safety of the infrastructure of this road type. With the development of a crash prediction model for ROR crashes on rural roads with a speed limit of 80 km/h, this study aims at making a start in providing the necessary new tools for a proactive road safety policy to road administrators in the Netherlands.
The paper presents a basic framework of the model development, comprising a problem description, the data used, and the method for developing the model. The model is developed with the utilization of generalized linear modeling in SAS, using the Negative Binomial probability distribution. A stepwise approach is used by adding one variable at a time, which forms the basis for striving for a parsimonious model and the evaluation of the model. The likelihood ratio test and the Akaike information criterion are used to assess the model fit, and parameter estimations are compared with literature findings to check for consistency.
The results comprise two important outcomes. One is a crash prediction model (CPM) to estimate the relative safety of rural roads with a speed limit of 80 km/h in a network. The other is a small set of estimated effects of traffic volume and road characteristics on ROR crash frequencies.
The results may lead to adjustments of the road design guidelines in the Netherlands and to further research on the quantification of risk factors with crash prediction models.
在荷兰，约 50%的道路交通死亡事故和 30%的道路交通伤害事故发生在限速 80 公里/小时的农村道路上。这些事故中有约 50%是驶出道路（ROR）事故。为了减少这类道路类型的事故数量，应注意改善这类道路的基础设施安全。通过开发限速 80 公里/小时的农村道路 ROR 事故预测模型，本研究旨在为荷兰道路管理者提供积极主动的道路安全政策所需的新工具。
本文介绍了模型开发的基本框架，包括问题描述、所用数据以及模型开发方法。该模型是利用 SAS 中的广义线性建模，采用负二项概率分布开发的。采用逐步方法，每次添加一个变量，这是为了追求简洁模型和评估模型的基础。似然比检验和 Akaike 信息准则用于评估模型拟合度，并将参数估计与文献结果进行比较，以检查一致性。
结果包括两个重要成果。一个是用于估计网络中限速 80 公里/小时的农村道路相对安全程度的碰撞预测模型（CPM）。另一个是关于交通量和道路特征对 ROR 碰撞频率影响的一组估计效应。
研究结果可能会导致荷兰道路设计指南的调整，并进一步研究使用碰撞预测模型量化风险因素。
