Essa Mohamed, Sayed Tarek
Department of Civil Engineering, University of British Columbia, 6250 Applied Science Lane, Vancouver, BC V6T 1Z4, Canada.
Accid Anal Prev. 2015 Nov;84:41-53. doi: 10.1016/j.aap.2015.08.005. Epub 2015 Aug 27.
Several studies have investigated the relationship between field-measured conflicts and the conflicts obtained from micro-simulation models using the Surrogate Safety Assessment Model (SSAM). Results from recent studies have shown that while reasonable correlation between simulated and real traffic conflicts can be obtained especially after proper calibration, more work is still needed to confirm that simulated conflicts provide safety measures beyond what can be expected from exposure. As well, the results have emphasized that using micro-simulation model to evaluate safety without proper model calibration should be avoided. The calibration process adjusts relevant simulation parameters to maximize the correlation between field-measured and simulated conflicts. The main objective of this study is to investigate the transferability of calibrated parameters of the traffic simulation model (VISSIM) for safety analysis between different sites. The main purpose is to examine whether the calibrated parameters, when applied to other sites, give reasonable results in terms of the correlation between the field-measured and the simulated conflicts. Eighty-three hours of video data from two signalized intersections in Surrey, BC were used in this study. Automated video-based computer vision techniques were used to extract vehicle trajectories and identify field-measured rear-end conflicts. Calibrated VISSIM parameters obtained from the first intersection which maximized the correlation between simulated and field-observed conflicts were used to estimate traffic conflicts at the second intersection and to compare the results to parameters optimized specifically for the second intersection. The results show that the VISSIM parameters are generally transferable between the two locations as the transferred parameters provided better correlation between simulated and field-measured conflicts than using the default VISSIM parameters. Of the six VISSIM parameters identified as important for the safety analysis, two parameters were directly transferable, three parameters were transferable to some degree, and one parameter was not transferable.
多项研究调查了现场测量的冲突与使用替代安全评估模型（SSAM）从微观模拟模型中获得的冲突之间的关系。近期研究结果表明，虽然尤其是经过适当校准后，可以在模拟冲突与实际交通冲突之间获得合理的相关性，但仍需要更多工作来确认模拟冲突所提供的安全措施是否超出了预期暴露水平所能提供的。同样，这些结果强调应避免在未进行适当模型校准的情况下使用微观模拟模型来评估安全性。校准过程会调整相关模拟参数，以最大化现场测量冲突与模拟冲突之间的相关性。本研究的主要目的是调查交通模拟模型（VISSIM）经校准的参数在不同地点之间用于安全分析时的可转移性。主要目的是检验经校准的参数应用于其他地点时，在现场测量冲突与模拟冲突之间的相关性方面是否能给出合理结果。本研究使用了来自加拿大不列颠哥伦比亚省萨里市两个信号控制交叉口的83小时视频数据。基于视频的自动计算机视觉技术被用于提取车辆轨迹并识别现场测量的追尾冲突。从第一个交叉口获得的经校准的VISSIM参数最大化了模拟冲突与现场观测冲突之间的相关性，这些参数被用于估计第二个交叉口的交通冲突，并将结果与专门为第二个交叉口优化的参数进行比较。结果表明，VISSIM参数通常可以在两个地点之间转移，因为转移后的参数在模拟冲突与现场测量冲突之间提供了比使用VISSIM默认参数更好的相关性。在确定对安全分析重要的六个VISSIM参数中，两个参数可直接转移，三个参数在一定程度上可转移，一个参数不可转移。
