Morning commute problem considering route choice, user heterogeneity and alternative system optima

This paper extends the bottleneck model to study congestion behavior of morning commute and its implications to transportation economics. The proposed model considers simultaneous route and departure time choices of heterogenous users who are distinguished by their valuation of travel time and punctual arrival. Moreover, two dynamic system optima are considered: one minimizes system cost in the unit of monetary value (i.e., the conventional system optimum, or SO) and the other minimizes system cost in the unit of travel time (i.e., the time-based SO, or TSO). Analytical solutions of no-toll equilibrium, SO and TSO are provided and the welfare effects of the corresponding dynamic congestion pricing options are examined, with and without route choice. The analyses suggest that TSO provides a Pareto-improving solution to the social inequity issue associated with SO. Although a TSO toll is generally discriminatory, anonymous TSO tolls do exist under certain circumstances. Unlike in the case with homogenous users, an SO toll generally alters users’ route choices by tolling the poorer users off the more desirable road, which worsens social inequity. Numerical examples are presented to verify analytical results.     

Traffic congestion pricing methodologies and technologies

This paper reviews the methods and technologies for congestion pricing of roads. Congestion tolls can be implemented at scales ranging from individual lanes on single links to national road networks. Tolls can be differentiated by time of day, road type and vehicle characteristics, and even set in real time according to current traffic conditions. Conventional toll booths have largely given way to electronic toll collection technologies. The main technology categories are roadside-only systems employing digital photography, tag & beacon systems that use short-range microwave technology, and in-vehicle-only systems based on either satellite or cellular network communications. The best technology choice depends on the application. The rate at which congestion pricing is implemented, and its ultimate scope, will depend on what technology is used and on what other functions and services it can perform.     

汽车轮胎侧偏特性影响因素的试验研究

应用轮胎静力学特性试验机，研究了低速条件下3种不同胎面花纹轮胎在干燥路面上的侧偏特性，主要分析了胎面花纹、轮胎负荷和轮胎气压等因素对轮胎侧偏特性的影响。结果表明：轮胎的Fy-α关系曲线形状与胎面花纹形式、轮胎负荷和胎压等均无关。而Mz-α关系曲线变化趋势与胎面花纹无关，却与轮胎负荷和气压有关；在相同试验条件下，顺向花纹轮胎具有更优异的附着性能和侧偏特性。     

拥挤收费下的路网交通评估模型研究

对城市实施拥堵收费策略的评估包括两个方面:一个是公共政策、经济环境、收费方式的技术可行性的评估;二是对拥堵收费区域内外的交通影响进行预估。文章在后一方面展开研究,利用交通网络分析的理论建立了拥挤收费下的交通网络评估模型,提出评估指标和求解算法。数值算例结果验证了评估模型以及算法的合理性,揭示了拥挤收费下收费区域内外交通模式变化的内在联系。表明只有将拥堵收费政策与城市良好的公交服务系统具体结合才能更好地起到减轻拥堵的预期效果。     

More gray hair—but for whom? Scenario-based simulations of elderly activity travel patterns in 2020

This paper reports the results of a scenario-based simulation study to explore mobility effects of an aging society in the Netherlands. Four accumulative behavioral scenario variants, embedded in an economic and demographic scenario are used to simulate possible future activity-travel patterns, using the Albatross system as the simulator. The variants account for likely differences in activity-travel behavior between elderly today and elderly in the future. Trends ongoing over the last decade in the Netherlands suggest that future elderly need to work longer, change their activity pattern with most growth occurring in the social/leisure activity category, will try to avoid morning peak hours by rescheduling their activities and may introduce more spatial diversity in terms of their residence location. Results show that these behavioral and spatial changes lead to a significant increase in travel demands as well as temporal, spatial and modal shifts in mobility patterns. We discuss possible policy implications of these predictions and evaluate the specific strength of activity-based models for studies of this kind.

Behavior of the cell transmission model and effectiveness of ramp metering

The paper characterizes the behavior of the cell transmission model of a freeway, divided into N sections or cells, each with one on-ramp and one off-ramp. The state of the dynamical system is the N-dimensional vector n of vehicle densities in the N sections. A feasible stationary demand pattern induces a unique equilibrium flow in each section. However, there is an infinite set—in fact a continuum—of equilibrium states, including a unique uncongested equilibrium n^u in which free flow speed prevails in all sections, and a unique most congested equilibrium n^con. In every other equilibrium n^e one or more sections are congested, and n^u  n^e  n^con. Every equilibrium is stable and every trajectory converges to some equilibrium state.Two implications for ramp metering are explored. First, if the demand exceeds capacity and the ramps are not metered, every trajectory converges to the most congested equilibrium. Moreover, there is a ramp metering strategy that increases discharge flows and reduces total travel time compared with the no-metering strategy. Second, even when the demand is feasible but the freeway is initially congested, there is a ramp metering strategy that moves the system to the uncongested equilibrium and reduces total travel time. The two conclusions show that congestion invariably indicates wastefulness of freeway resources that ramp metering can eliminate.     

标准汉字的自动识别

讨论一类黑白模式(标准汉字)识别问题.采用Zernike矩不变量作为模式的特征拟定自动识别方案,并通过试验软件进行了实算分析,说明本文所拟定的识别方案是可行的.     

公共自行车交通发展模式比较

解决城市交通出行困难的问题,建立多模式绿色交通体系是必然选择。围绕北京、杭州和上海三种不同的公共自行车交通发展模式,分析了各种模式的特点、系统运营状况以及未来需改进的方面。指出公共自行车系统的引入的确可以大大改善人们的出行条件,对小汽车的过度使用也起到一定的抑制作用。但是,公共自行车系统的发展需要政府有明确的目标并提供有效支持,应鼓励采取企业与政府合作的模式,以充分发挥企业控制成本、技术创新优势,以及政府引导和整合社会资源优势。