Operating speed profiles represent drivers’ responses to roadway geometry and are widely used to evaluate safety performance of roadway design. To predict operating speed profile, the majority of early research followed a two-step modeling procedure: (1) estimate speeds at start, middle, and end points of road segments, and (2) fill the profile between the points with assumed driver behavior. This sparse-spot-based modeling strategy has been shown to be inadequate for capturing the complex speed changes resulting from the overlapping horizontal and vertical curves on mountainous roads. This paper proposes a high-resolution modeling approach for operating speeds measured in a dense series of equidistant spots along a road. This type of model is more conducive to analysis of mountainous freeway alignments as operating speeds are predicted along the entire roadway. The high-resolution data were obtained, using the Tongji University Driving Simulator, from a simulated section of mountainous freeway. The estimated linear mixed model includes geometric variables representing the road upstream and downstream of each data collection spot. To determine the suitable lengths of the upstream and downstream segments, the data were extracted from several alternative segment lengths, including fixed lengths and varying downstream length accordingly to sight distances. The model with a spherical structure of error covariance, using geometric data extracted from 300-meter upstream and downstream segments, performed the best. An out-of-sample evaluation of the model has the mean absolute error of 3.2 km/h and the root mean square error of 4.2 km/h, which indicates a promising prediction ability of the proposed model.

行驶速度曲线表示驾驶员对道路几何形状的反应，被广泛用于评估道路设计的安全性能。为了预测行驶速度分布，大多数早期研究遵循两步建模程序：（1）估算路段起点，中间和终点的速度，以及（2）用假定的驾驶员行为填充点之间的轮廓。事实证明，这种基于稀疏点的建模策略不足以捕获由于山区道路上水平和垂直曲线重叠而产生的复杂速度变化。本文提出了一种高分辨率的建模方法，用于在沿道路的一系列等距密集点上测得的行驶速度。这种类型的模型更有助于分析山区高速公路路线，因为可以预测整个道路的运行速度。使用同济大学驾驶模拟器从山区高速公路的模拟部分获得高分辨率数据。估计的线性混合模型包括代表每个数据收集点上游和下游道路的几何变量。为了确定上游段和下游段的合适长度，从几种替代段的长度中提取了数据，包括固定长度和根据视距而变化的下游长度。具有误差协方差的球形结构的模型使用从300米的上游和下游区段提取的几何数据，表现最佳。