加利福尼亚州车辆合乘系统运行效果

为了解加利福尼亚州HOV系统的运行效果,基于交通量检测器收集的数据,对HOV系统进行全面分析、评价。最终得到4个主要结论：1）与多条普通车道构成的高速公路相比,包含1条HOV车道的高速公路损失了20%的通行能力;2）HOV车道通常处于两种运行状态,一种是HOV车道未被充分利用,另一种是HOV车道处于超负荷、降级运行状态;3）HOV车道未显著提高小汽车合乘比例;4）在一个相当出色的交通管理系统中,HOV车道并未从整体上缓解道路交通拥堵状况。     

设计时速与直行车道数对饱和流率的影响分析

信号交叉口作为城市道路的重要组成部分,其饱和流率受众多因素的影响。以美国通行能力手册中饱和流率模型为基础,通过对北京市典型信号交叉口车头时距的现场测定,对设计时速与直行车道数对饱和流率的影响进行研究,可完善饱和流率修正模型。     

双洞八车道公路隧道施工方案研究

双洞八车道公路隧道最大跨度在23m左右,扁平率小于0．5,为超大断面隧道。通过对某双洞八车道公路隧道在几种围岩条件下多种施工开挖方案的有限元计算分析,得出双洞八车道公路隧道宜采用三心圆拱型断面和复合式支护衬砌,软弱围岩段宜采用双侧壁导坑法开挖,并通过相似模型实验研究,得到隧道围岩在施工中的位移发展,遵循台阶式发展过程并符合Hill函数变化规律,可对类似工程设计施工提供类比和指导。     

Dynamic pricing for managed lanes with multiple entrances and exits

Priced managed lanes are increasingly being used to better utilize the existing capacity of the roadway to relieve congestion and offer reliable travel time to road users. In this paper, we investigate the optimization problem for pricing managed lanes with multiple entrances and exits which seeks to maximize the revenue and minimize the total system travel time (TSTT) over a finite horizon. We propose a lane choice model where travelers make online decisions at each diverge point considering all routes on a managed lane network. We formulate the problem as a deterministic Markov decision process and solve it using the value function approximation (VFA) method for different initializations. We compare the performance of the toll policies predicted by the VFA method against the myopic revenue policy which maximizes the revenue only at the current timestep and two heuristic policies based on the measured densities on the managed and general purpose lanes (GPLs). We test the results on four different test networks. The primary findings from our research suggest the usefulness of the VFA method for determining dynamic tolls. The best-found objective value from the method at its termination is better than other heuristics for all test networks with average improvements in the objective ranging between 10% and 90% for revenue maximization and 0–27% for TSTT minimization. Certain VFA initializations obtain best-found toll profiles within first 5–50 iterations which warrants computational time savings. Our findings also indicate that the revenue-maximizing optimal policies follow the “jam-and-harvest” behavior where the GPLs are pushed towards congestion in the earlier time steps to generate higher revenue in the later time steps, a characteristic not observed for the policies minimizing TSTT.     

信号控制平面交叉口通行能力与信号周期之间的关系

探讨了信号控制交叉口的通行能力与信号周期之间的关系,研究发现信号交叉口进口道的通行能力并不一定随信号周期之增加而增加;给出进口道通行能力与信号周期之间关系的判断准则,并运用该准则进一步分析整个交叉口的通行能力与信号周期的关系。     

Investigating preference heterogeneity in Value of Time (VOT) and Value of Reliability (VOR) estimation for managed lanes

This paper presents an empirical study in investigating user heterogeneity of Value of Time (VOT) and Value of Reliability (VOR). Combined Revealed Preference (RP) and Stated Preference (SP) data were used to understand traveler choice behavior regarding the usage of managed lanes (MLs). The data were obtained from the South Florida Expressway Stated Preference Survey, which focused on automobile drivers who had traveled on the I-75, I-95, or SR 826 corridors in South Florida. Mixed logit modeling was applied and indicated an average value of $13.55 per hour for VOT and $16.13 per hour for VOR. Potential sources of heterogeneity in user sensitivities to time, reliability, and cost were identified and quantified by adding interaction effects of the variables in the mixed logit model. The findings indicated that various socioeconomic demographic characteristics and trip attributes contributed to the variations in VOT and VOR at different magnitudes. The results of this study contribute to a better understanding on what attributes lead to higher or lower VOT and VOR and to what extent. These findings can be incorporated into the demand forecasting process and lead to better estimates and enhanced analytical capabilities in various applications, such as toll feasibility studies, pricing strategy and policy evaluations, and impact analysis.     

大城市合乘优先的规划方法研究

针对我国大城市及中心区的交通特征,分析合乘优先规划的影响因素;借鉴世界发达国家实施合乘优先的经验,提出合乘优先的规划内容;以上海市中心区为试点,依据规划方法与相关交通调查,提出了上海市中心区合乘优先规划建议。     

Variation in the value of travel time savings and its impact on the benefits of managed lanes

This paper examines the variation in the value of travel time savings (VTTS) for travelers with a managed lane (ML) option when taking an ordinary trip versus a trip that is unusual in some way. VTTS estimates vary substantially depending on the urgency of the trip made. At the low end, the mean VTTS for a traveler who wants to make extra stops and still arrive on time is approximately 10% higher than that for an ordinary trip. At the high end, a traveler running late for an appointment shows a mean VTTS that is approximately 300% higher than that for an ordinary trip. These estimates vary widely over the population of travelers. In light of these variations, the value of an uncongested travel alternative (such as MLs) is examined and found to be greatly undervalued if using typical VTTS estimates.     

组团城市快速通道体系研究——以太仓市为例

基于长三角一体化发展背景,以太仓市为例,研究组团城市快速通道分布体系。研究显示与单中心城市相比,“组团式”城市的交通出行特征有显著差异性,主要以组团联系和组团内部交通为主,大流量廊道基本沿着组团OD走向,但又存在中间大量的郊区段并伴随一定的潮汐交通现象。研究表明:组团城市建设快速路是完全可行的,快速路的选线上要兼顾组团联系为主,形态上以服务大客运OD为主。另外快速路的末端可采用快捷路（或主干路）衔接,延伸快速路敷设范围,近期保证设施效益的最大化,远期也可快捷路快速化改造,实现城市快速路网络化布局的可能。     

The evaluation of high occupancy vehicle lanes on sun yat‐sen freeway in Taiwan

This study proposes a methodological framework to incorporate latent factors, including direct and indirect perceptions, as the explanatory variables in a discrete choice models using revealed preference and stated preference data sets. The methodology requires the estimation of a model system comprising of a discrete choice model and the structural and measurement equations of a latent variable model. The application involves the evaluation of responses to the new high occupancy vehicle (HOV) lanes on the Sun Yat‐Sen Freeway in Taiwan. The results obtained from this study provide valuable insights into the planning and assessment of HOV lanes.