Department of Civil Engineering, National Institute of Technology, Warangal, India.
Traffic Inj Prev. 2023;24(4):331-337. doi: 10.1080/15389588.2023.2184203. Epub 2023 Mar 13.
Current Road geometric design processes disregard stochastic aspects, resulting in inadequate traffic safety considerations. In addition, the primary sources of crash data are obtained from police department, insurance agency and hospitals, where detailed investigation is not carried out from a transportation perspective. So, the data obtained from these sources may or may not be reliable. The main objective of this study is to account uncertainties using reliability as a tool that considers slow down the vehicle while they maneuver the curve and to develop thresholds of reliability index associated with sight distance based on operating speed design consistent measure as a surrogate safety measure rather than using crash data.
This study proposes a thresholds of reliability index associated with sight distance for various operating speed ranges based on design consistent measure. In addition, established the relationship between the consistency levels, geometric characteristics and vehicle characteristics. In this study, classical topography survey was carried out on the field using total station. The data collected comprises speed data and geometric data of 18 horizontal curves (Lane based analysis was carried out). A total of 3042 free flowing vehicle speeds have been extracted from the video graphic survey and used in the analysis.
The threshold values of reliability indices associated with sight distance is higher as the operating speed increases for the section to be a consistent design section. The results from the Binary Logit Model show that the consistency level is significantly affected by deflection angle and operating speed. Deflection angle was negatively correlated with the in-consistency level, and the operating speed was positively correlated with in-consistency level.
From Binary Logit Model (BLM) results, we can conclude that an increase in the value of deflection angle will significantly decrease the probability of In-Consistent level, which indicates uncertainties that cause drivers to change the path of vehicle or rate of deceleration of the vehicle while maneuvering the curve will be decreased. Whereas, increase in the operating speed will significantly increase the probability of In-Consistency level.
当前的道路几何设计过程忽略了随机因素，因此对交通安全的考虑不够充分。此外，事故数据的主要来源是警察局、保险公司和医院，但这些地方并没有从交通角度进行详细调查。因此，这些来源获得的数据可能可靠，也可能不可靠。本研究的主要目的是利用可靠性作为一种工具来考虑车辆在转弯时减速的不确定性，并根据运行速度设计一致的度量标准，制定与视距相关的可靠性指标阈值，作为替代安全措施，而不是使用事故数据。
本研究提出了基于设计一致的度量标准，与各种运行速度范围相关的视距可靠性指标阈值。此外，还建立了一致性水平、几何特征和车辆特征之间的关系。在本研究中，使用全站仪在现场进行了经典地形测量。收集的数据包括 18 个平曲线的速度数据和几何数据（基于车道的分析）。从视频图形调查中提取了 3042 个自由流动车辆速度，并用于分析。
对于一致性设计路段，随着运行速度的增加，与视距相关的可靠性指标的阈值值越高。二元逻辑模型的结果表明，一致性水平受到偏转角和运行速度的显著影响。偏转角与不一致水平呈负相关，运行速度与不一致水平呈正相关。
从二元逻辑模型（BLM）的结果可以得出结论，偏转角值的增加将显著降低不一致水平的概率，这表明在转弯时，导致驾驶员改变车辆路径或车辆减速的不确定性将降低。而运行速度的增加将显著提高不一致水平的概率。
