Variable speed limit (VSL) system has been recognised as an active traffic management strategy to improve traffic safety and operational efficiency. The development of connected vehicle (CV) technologies have a potential to improve VSL systems because CVs can provide continuous and precise traffic condition as the input of VSL algorithm as well as real-time recommended speed to drivers. To demonstrate the improvement of the VSL performance from CV technologies, this study presents the evaluation of a VSL system's safety and operational impact on CVs, non-CVs, and overall traffic conditions, based on a field test in interstate 5 corridor, Seattle. A hierarchical evaluation framework was proposed to explore the effectiveness of the implemented algorithm. The framework consists of three parts, i.e. manoeuvring, safety, and operation. Each part conducts data analysis and statistical tests from traffic sensors and CVs. The findings indicate that the VSL system is able to inform drivers to follow the recommended speed and improve traffic operation even at a low penetration rate. However, the stability of traffic flow is decreased in certain sections. Therefore, the potential improvement of the VSL algorithm is presented based on the findings.

中文翻译：

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在联网车辆环境下使用分层框架评估变速限制系统：西雅图现场测试的案例研究

变速限制（VSL）系统已被公认为是一种主动的交通管理策略，可以提高交通安全性和运营效率。联网车辆（CV）技术的发展具有改善VSL系统的潜力，因为CV可以提供连续且精确的交通状况作为VSL算法的输入，并为驾驶员提供实时推荐速度。为了证明CV技术可改善VSL性能，本研究基于西雅图5号州际走廊的现场测试，对VSL系统对CV，非CV和整体交通状况的安全性和运营影响进行了评估。提出了一种层次评估框架，以探索所实现算法的有效性。该框架包括三个部分，即操纵，安全和操作。每个部分都从交通传感器和CV进行数据分析和统计测试。研究结果表明，VSL系统即使在低渗透率的情况下也能够通知驾驶员遵循建议的速度并改善交通运营。但是，某些部分的交通流量的稳定性下降。因此，基于这些发现，提出了VSL算法的潜在改进。