以交通检测系统获取的车道流量和速度为模型输入，分别提出基于延误损失、事故损失和综合损失等3类步进式可变限速控制。综合现有基于流量和基于车速离散性算法估计了高速公路事故发生率，提出了基于延误和事故发生率的路段综合损失计算方法。以青兰高速莱芜区约20 km的路段为实例，模拟了8组可变限速牌，通过微观仿真验证了提出的3种算法。结果证明，相比于静态控制，建立的3种模型均显著降低了主线车流的停车次数、停车延误和综合延误，改善了车辆行驶的平稳性，但主线车辆旅行时间略有增加。根据敏感性分析发现，随着驾驶员对限速值服从率的下降，可变限速控制的效益也逐渐降低，尤其低于80%时，下降显著；当低于60%时，基本保持不变。%Taking traffic volume and speed collected by traffic detection system as input variables, this paper proposes three kinds of step-by-step variable speed limit control models to minimize estimated delay cost, crash cost and comprehensive cost, respectively. The freeway crash rate is estimated based on volume-over-capacity and speed deviation by the existing model, and then the comprehensive cost is computed in terms of estimated delay and crash rate. In tests that used field freeway from about 20km segment of Qing-lan freeway with eight variable speed limit signs, these developed three controls show promise in reducing the numbers of vehicle stops, stopped delay and equivalent travel delay based on micro simulation results, smoothing traffic speed and improving traffic safety. Nevertheless, travel time of freeway vehicles is increased a little. Additionally, sensitivity analysis of driver compliance rate indicates that benefits of variable speed limit are gradually reduced as compliance rate decreased. When the compliance rate is below 80%, benefits are significantly decreased;and benefits are essentially unchanged if it is less than a threshold of 60%.
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