道路限速与拥堵收费的综合分析、建模和优化

Speed limits have been employed worldwide as a straightforward way to regulate vehicular speed, thereby enhancing safety and reducing fuel consumption and emissions. In view of the fact that road traffic is one of the major sources for greenhouse emission and fuel consumption, speed limits have also been introduced to prohibit high speed driving for energy and environmental consideration. However, imposing speed limits will inevitably impact travel times or mobility. Intuitively, if a speed limit is imposed, travelers will adapt their driving speed to reduce speeding ticket risk and thus incur a longer travel time. Besides speed limit, road pricing is also a powerful tool for traffic flow management, which has been recognized to reduce traffic congestion in both theory and practice. Speed limit increases travel time on a road to deter traffic flow, whereas road pricing increases monetary cost but decreases travel time by reducing traffic volume and thus increasing speed on a congested road. Their different but complementary mechanisms for traffic regulation make their integration a promising instrument to improve system performance. This project proposes to investigate the optimal design of speed limits and congestion pricing for the purpose of safety enhancement, energy saving and emission reduction on general networks. The first part of the project will focus on characterizing travelers' route choice behavior and adherence to a given speed limit scheme at user equilibrium from a system-wide perspective, which is different from the previous affluent studies on the effectiveness of speed limits but mostly from a local road perspective. The subjective travel time cost, the perceived crash risk, and the perceived speeding ticket cost of travelers will be taken into account as determinant factors for their actual speed and route choices. The second part will focus on optimal design of speed limits for enhancing safety and reducing emission and energy consumption. Multiple integer levels of speed limit are considered and the resulting speed limit design problem is formulated as a bi-level discrete network design problem and solved efficiently by the latest novel methods developed by the investigator. Based on the previous two parts, the third part of the project will investigate hybrid schemes of speed limits and road pricing for network flow control and management. Given the wide implementation of speed limits around the world and the widely recognized effectiveness of road pricing but only limited integrated considerations of the two strategies from a system-wide perspective, the proposed research is of great importance. It provides a new perspective to look into the impacts of speed limits and road pricing on traffic equilibrium and system performance in networks, and help the system planner make a better choice of speed limits and road pricing for multi-objective system optimization.

道路限速不仅可以增强交通安全，同时有助于减少车辆燃料消耗和尾气排放，因而在实际中被广泛采用。路段限速会影响行程时间而影响路网交通平衡。拥堵收费通过额外收费来干预交通流，在理论和实际中都已被证明能有效的缓解拥堵。然而二者调控交通流的机制并不相同，因此需要根据实际灵活运用：在拥堵路段，收费可以减少交通流量；在非拥堵路段，限速可以增强交通安全并减少燃料消耗和尾气排放。两者的综合方案有可能达到某些单独使用其中一种方案无法达到的目标。 本项目将从交通网络的层面来考虑限速和拥堵收费的影响以设计和优化二者的综合方案，为管理路网交通流提供理论基础。本项目包括三个部分：第一部分将关注限速对路网的全局影响，讨论给定限速方案下的交通网络平衡；第二部分将以增强交通安全和节能减排为目标，着重讨论路网限速方案的优化；在前两部分的基础上，第三部分将研究如何运用道路限速和道路收费的综合策略，以实现对路网交通流的科学管理。

为了提高驾驶安全性、减少能源消耗和汽车尾气排放，一些欧美国家和我国先后在高速公路上，设置道路限速来降低道路车速。然而，道路限速会不可避免地影响人们的出行时间进而影响路网交通分布。道路拥堵收费也可以有效地缓解交通拥堵，其与道路限速调控交通流的机制并不相同。.基于以上背景，本项目从交通网络和交通系统的层面来考虑道路限速和拥堵收费的影响。本项目提出的模型和工具对于评估道路限速对于路网的全局影响具有重要意义，尤其是对给定限速方案下的交通网络平衡，以增强交通安全和节能减排为目标，着重讨论路网限速方案的优化更为重要。项目还对道路限速和道路收费的综合策略进行了研究，两者的综合方案达到某些单独使用其中一种方案无法达到的目标，有助于实现对路网交通流更为科学的管理。.项目取得的成果有：研究了考虑通勤者长期响应时可变限速的有效性问题，结果显示离散的可变限速系统可以避免或延缓由于激活的瓶颈造成的通行能力下降，减少排队延迟；研究了道路使用者在速度选择区不严格遵守限速规定时，限速对交通均衡的局部以及全局影响，提出了一种考虑特定路段限速情形下用户平衡问题的求解算法；研究了交通网络设计以及所有权制的帕累托改进，研究发现在一些温和的假设下，任何非支配帕累托改进方案中，最佳的通行能力扩大是由路段流量唯一确定的；研究了限理性用户均衡中的理性调整过程，使用可分离的路段旅行成本函数证明了有经典解的BRUE-RBAP稳定性，验证了各种有限理性阈值。此外，项目组还对动态拥挤收费策略、离散多方式交通网络设计问题、网络可靠性和通勤者的风险偏好行为、惯性路径选择行为、驾驶员日常的路径选择行为实验、充电站选址等进行了研究工作。经统计，项目已取得的成果包括：发表或接受发表标注SCI论文11篇，其中Transportation Science 1篇、Transportation Research Part B 3篇、Transportation Research Part C 6篇；举办国际学术会议2次，参加国内外学术会议13人次。培养博士研究生3名（其中1名预计2018.6毕业），硕士研究生1名（已转博）。