Recent studies have leveraged the existence of network macroscopic fundamental diagrams (MFD) to develop regional control strategies for urban traffic networks. Existing MFD-based control strategies focus on vehicle movement within and across regions of an urban network and do not consider how freeway traffic can be controlled to improve overall traffic operations in mixed freeway and urban networks. The purpose of this study is to develop a coordinated traffic management scheme that simultaneously implements perimeter flow control on an urban network and variable speed limits (VSL) on a freeway to reduce total travel time in such a mixed network. By slowing down vehicles traveling along the freeway, VSL can effectively meter traffic exiting the freeway into the urban network. This can be particularly useful since freeways often have large storage capacities and vehicles accumulating on freeways might be less disruptive to overall system operations than on urban streets. VSL can also be used to change where freeway vehicles enter the urban network to benefit the entire system. The combined control strategy is implemented in a model predictive control framework with several realistic constraints, such as gradual reductions in freeway speed limit. Numerical tests suggest that the combined implementation of VSL and perimeter metering control can improve traffic operations compared with perimeter metering alone.

最近的研究利用网络宏观基本图 (MFD) 的存在来制定城市交通网络的区域控制策略。现有的基于 MFD 的控制策略侧重于城市网络区域内和跨区域的车辆移动，并未考虑如何控制高速公路交通以改善高速公路和城市混合网络中的整体交通运营。本研究的目的是开发一种协调的交通管理方案，同时在城市网络上实施周边流量控制和高速公路上的可变速度限制 (VSL)，以减少这种混合网络中的总旅行时间。通过减慢沿高速公路行驶的车辆，VSL 可以有效地计量离开高速公路进入城市网络的交通量。这可能特别有用，因为高速公路通常具有较大的存储容量，并且与城市街道相比，在高速公路上堆积的车辆对整个系统运行的破坏性较小。VSL 还可用于改变高速公路车辆进入城市网络的位置，从而使整个系统受益。组合控制策略在模型预测控制框架中实施，具有几个现实约束，例如高速公路限速的逐渐降低。数值试验表明，与单独的周边计量相比，VSL 和周边计量控制的联合实施可以改善交通运营。VSL 还可用于改变高速公路车辆进入城市网络的位置，从而使整个系统受益。组合控制策略在模型预测控制框架中实施，具有几个现实约束，例如高速公路限速的逐渐降低。数值试验表明，与单独的周边计量相比，VSL 和周边计量控制的联合实施可以改善交通运营。VSL 还可用于改变高速公路车辆进入城市网络的位置，从而使整个系统受益。组合控制策略在模型预测控制框架中实施，具有几个现实约束，例如高速公路限速的逐渐降低。数值试验表明，与单独的周边计量相比，VSL 和周边计量控制的联合实施可以改善交通运营。