王玲

       随着城市经济的发展和道路系统的完善，大型活动（文艺演出、会展等）、占道施工等事件的出现频率频繁，由于此类事件不仅是事先有计划安排的，而且它们所引发的交通需求具有非常态性，故将此类事件所引发的交通需求称之为可预知特殊需求。可预知特殊需求是城市发展中不可或缺的一部分，但会给交通带来巨大的压力，甚至产生严重交通拥堵等。其主要特征是影响范围广泛性与可预知性，广泛性决定了对它实施交通管控的必要性，可预知性决定了提前制定交通管控预案的可能性。

       可预知特殊需求下，交通供需严重失衡，论文针对这一交通特征，研究通过交通网络变结构预案来改变交通网络的空间资源，提高路段与交叉口的方向性通行能力，从而改善可预知特殊需求时交通供需的功能性不匹配，缓解交通拥挤。

论文从交通网络与结构的基本定义出发，阐述了交通网络变结构的内涵。在分析可预知特殊需求交通特征的基础上，确定了可预知特殊需求交通分析范围与影响范围划定流程及阈值，探讨了路段变结构与交叉口变结构的实施顺序，并提出了可预知特殊需求下交通网络变结构预案生成流程。

       论文分析了针对可预知特殊需求的路段可变方向车道、路段临时单向交通、交叉口可变转向车道和交叉口临时左转禁限这四种交通网络变结构措施，解释了它们能改善可预知特殊需求交通状况的根本原因与实施的必要性，提出了实施的道路条件及交通条件，以及路段变结构与交叉口变结构优化目标和流程。最后，用首都体育馆的大型活动和三里河四巷占道施工这两个案例，在分析它们交通影响范围基础上，结合活动发生地的区域道路网络，对所建议的交通网络变结构预案进行验证，结果表明，所建议的预案能有效地改善交通状况。 

关键词：可预知特殊需求，交通网络变结构，路段可变方向车道，路段临时单向交通，交叉口可变转向车道，交叉口临时左转禁限 

     With the development of city economy and traffic network, the large-scale event and road maintenance happen more and more frequently. These events are pre-arranged and their traffic is abnormal, hence, they are defined as planned special events, their traffic demand is called planned special event traffic. Planned special events are indispensable during the course of city development, though they would result in enormous traffic pressure and congestion. The main features of planned events are broad impact and predictability. The broad impact indicates that the control strategy is highly necessary, and the predictability means the contral strategy can be possibly made before the events.
     When planned special events happen, there would be a serious mismatch between traffic demand and supply. In response, this paper studies how to formulate variable traffic network structure strategy which is used to change the space resources of traffic network and improve the directional capacity of road segements and intersections.
     This paper interpreted the potential meaning of traffic network variable structure from the views of the definition of traffic network and structure. After analyzing the traffic feature of planned special events, the process and threshold of traffic analysis area and traffic impact area were given, at the same time, the order of variable road segment strcture and variable intersection structure was analyzed. Based on the former analysis, this study set up the procedure which is used to formulate the traffic network variable structure strategy under planned special events.
     The paper analyzed four traffic network variable structures when planned special events happen, these were reversible directional road, temporary one-way traffic, reversible intersection turning lane and temporary left turn forbiddance, explained why they could improve the planned special events’ traffic. The road condition and traffic condition of traffic network variable structures were given, and then the optimization of traffic network variable structures was established. At the end of this paper, two cases, those were Capital Gymnasium’s large-scale event and South 4th Sanlihe road’s road maintenance, were used to prove the efficiency of traffic network variable structures.

Key Words: planned special events, variable traffic network structure, reversible directional road, temporary one-way traffic, reversible intersection turning lane, temporary left turn forbiddance