The stability of stochastic equilibrium in a two-link transportation network

Most research and applications of network equilibrium models are based on the assumption that traffic volumes on roadways are virtually certain to be at or near their equilibrium values if the equilibrium volumes exist and are unique. However, it has long been known that this assumption can be violated in deterministic models. This paper presents an investigation of the stability of stochastic equilibrium in a two-link network. The stability of deterministic equilibrium also is discussed briefly. Equilibrium is defined to be stable if it is unique and the link volumes converge over time to their equilibrium values regardless of the initial conditions. Three models of route choice decision-making over time are formulated, and the stability of equilibrium is investigated for each. It is shown that even when equilibrium is unique, link volumes may converge to their equilibrium values, oscillate about equilibrium perpetually, or converge to values that may be considerably different from the equilibrium ones, depending on the details of the route choice decision-making process. Moreover, even when convergence of link volumes to equilibrium is assured, the convergence may be too slow to justify the standard assumption that these volumes are usually at or near their equilibrium values. When link volumes converge to non-equilibrium values, the levels at which the volumes stabilize typically depend on the initial link volumes or perceptions of travel costs. Conditions sufficient to assure convergence to equilibrium in two of the three models of route choice decision-making are presented, and these conditions are interpreted in terms of the route choice decision-making process.     

让梦想漂流的艺术家

生活往现代大都市,我们都在流动,我们都在飘泊,我们都没有根,我们都对自己身处的城市欠缺归属感。某天,有人发现在香港维港上漂流着一间小房子,房子主人黄国才不是在求救,他是在寻梦,寻一个飘泊流动的艺术梦想。     

Behavioral adjustments and equity effects of congestion pricing: Analysis of morning commutes during the Stockholm Trial

This paper assesses the horizontal and vertical equity effects of the Stockholm Trial with Congestion Pricing for morning commuters, in terms of both travel behavioral adjustments and welfare effects, as a result of the toll’s direct effects and the behavioral adjustments. We consider specifically two behavioral adjustments: mode choice and departure time choice. Initial car drivers crossing the toll cordon had a 15 percentage-points higher rate of switching to public transit as compared with those not crossing the cordon. We also find some evidence of peak spreading, in particular toward a later departure time, as a result of the charging scheme, but most people choose a departure time within 15 min both before and during the trial. In the welfare analysis, we found no clear pattern of increasing burden by either increasing income or decreasing income, and the increase in the Gini Coefficient was insignificant. We also found no significant difference in either the mode-switching behavior or the average welfare effect for women versus for men.     

Equilibria of bilateral taxi–customer searching and meeting on networks

This paper proposes an equilibrium model to characterize the bilateral searching and meeting between customers and taxis on road networks. A taxi driver searches or waits for a customer by considering both the expected searching or waiting time cost and ride revenue, and a customer seeks a taxi ride to minimize full trip price. We suppose that the bilateral taxi–customer searching and meeting occurs anywhere in residential and commercial zones or at prescribed taxi stands, such as an airport or a railway station. We propose a meeting function to spell out the search and meeting frictions that arise endogenously as a result of the distinct spatial feature of the area and the taxi–customer moving decisions. With the proposed meeting function and the assumptions underlying taxi–customer search behaviors, the stationary competitive equilibrium achieved at fixed fare prices is determined when the demand of the customers matches the supply of taxis or there is market clearing at the prevailing searching and waiting times in every meeting location. We establish the existence of such an equilibrium by virtue of Brouwer’s fixed-point theorem and demonstrate its principal operational characteristics with a numerical example.     

Avoiding specification errors in estimating the value of time

Sources of specification as well as measurement error in previous estimates of the value of time are examined in this paper, and a new set of estimates avoiding these errors is presented. The sources of specification error being analyzed are: (1) failure to take account of drivers' uncertainty in making their choices between alternative routes or modes, which was found empirically to bias the value of time estimate 50 percent or more; (2) the differential in comfort and similar intangible characteristics between two modes; and (3) the inability to account for cross-time substitutions by travelers in peak-hour conditions. Ways of avoiding these sources of error are suggested and implemented. The choice between “reported” and “measured” data is re-examined, with an emphasis on random rather than systematic perception errors by travelers. Some resulting estimates are: $1.91 per hour per adult for off-peak work trips, $2.08 for off-peak social-recreational trips, and $5.17 for peak-hour work trips.     

A cause of oversupply and failure in the shipping market: measuring herding behavior effects

ABSTRACT

The shipping market is volatile. In general, the shipping market cycle shows four stages, through—recovery—peak—collapse, while a upward trend lasts for 7~8 years and a downward trend for another 7~8 years. So the market’s bubble is not sustainable but always ends in a recessionary trend. The economic cycle is common knowledge and an axiom of the shipping industry, but many ship-owners take no account of it. Previous study stated that ship-owners’ fears, triggered by a violently changeable market, make them mimic the crowd mind or herd mentality, following market sentiment. This study aims to measure the effects of herding behavior (HB), triggered by market sentiment, on the shipping market. We attempt to address two research questions: (1) How does HB arise, and what course does it follow? (2) How many vessels (or how many tons) were purchased under the influence of HB? We estimate that 50.5% (227.8 vessels) of the total vessels or 30.4% (3,670.2 tons) of the total tonnage were purchased under the influence of HB. Looking at international finance, we found that ship investment HB is a very strong factor of the recent shipping market, at least in Korea.     

Fuel price changes and their impacts on urban transport – a literature review using bibliometric and content analysis techniques, 1972–2017

ABSTRACT

While the period of heightened oil prices in 2005–2014 has attracted considerable academic and policy attention, there is scant cross-disciplinary research considering energy price, transport and land use together. In car dependent societies many socio-economically disadvantaged areas often lack public and active transport accessibility. Emerging research focus has been placed on issues of transport equity including effects of fuel prices. We reviewed 45 years (1972–2017) of publications about fuel price impacts, transport, and urban context, drawn from Web of Science listed publications. Bibliographic citation analysis reveals eight major research clusters with a set of inter-city comparative studies at their centre. The historical evolution, geographical trends, research approaches and the key themes are revealed by context analysis. The paper highlights the need for further studies looking at energy, transport and land use interaction, and suggests a greater focus on transport equity.     

Autonomous vehicles: scientometric and bibliometric review*

ABSTRACT

This paper presents a scientometric and bibliometric review of the research on autonomous vehicles (AVs) to identify its main characteristics, evolution, and potential trends for future studies. Relevant articles were searched on WoS, yielding a research corpus of 10,580 papers, and the software CiteSpace was subsequently used for analysis. The results showed that AV research is heterogeneous and registered a growing demand over time. Multidisciplinarity is present, with 96 science fields being identified. As in any other sector, it is necessary to understand broader aspects of this industry such as the market factors surrounding it, as well as other economic and managerial issues. In this sense, we observed a migration of the research field from multidisciplinarity to pluridisciplinarity with a greater number of studies focusing on the latter. We understand that terminology standardisation contributes to achieving pluridisciplinarity. As such, it is important to highlight that sustainability, public policies, liability, and safety, as well as business issues such as performance and business models are some of the tendencies in the field of AVs. For future studies, we suggest a more in-depth analysis of publications in terms of individual search terms, as well as the sub-areas identified as trends in this paper.     

忘掉时间的表

今个月先后拍了两枚腕表,一枚是价值连城的三问表(minuterepeater),另一则是这枚爱马仕Arceau Temps Suspendu。两枚都在9点钟位置设有一个奇妙的按钮:你按下三问表那按钮,它会以敲打簧片的声音向你报时,让你听到时间;你按下爱马仕那个,它却让时间在你眼前消失,使你不知今夕何夕。