Study on some bus transport networks in China with considering spatial characteristics

Many real-world networks are embedded in spaces. Recent studies have found that spatial characteristics are closely related to network features. Bus transport networks (BTNs) are typical spatially embedded networks, but their spatial characteristics are commonly disregarded in previous researches. In this paper, we propose a new spatial representation model for BTNs with information on the geographical location of bus stations and routes, for which we named as the ES model. The new model aids in the study of real-world BTNs. By performing a statistical study with the new representation model on three typical BTNs in China, namely the Beijing, Shanghai and Hangzhou BTNs, we identify some network features that are consistent with those revealed by previous studies, as well as some new features such as high clustering of short-distance station pairs (SSPs) and small average number of bus routes in a path. The result shows that the existence of SSPs can significantly influence the characteristics of BTNs. Besides, with the help of the ES model, we designed a new transfer algorithm for BTNs.     

Development of an indicator to assess the spatial fit of discrete choice models

Discrete choice models are increasingly implemented using geographical data. When this is the case, it may not be sufficient to project market shares accurately, but also to correctly replicate the spatial pattern of choices. Analysts might then be interested in assessing the results of a model’s fit relative to the spatial distribution of the observed responses. While canonical approaches exist for the exploratory spatial analysis of continuous variables, similar tools have not been widely implemented for discrete choice models, where the variable of interest is categorical. For this reason, despite recent progress with spatial models for discrete outcomes, there is still not a simple and intuitive tool to assess the quality of the spatial fit of a discrete choice model. The objective of this paper is to introduce a new indicator of spatial fit that can be applied to the results of discrete choice models. Utility of the indicator is explored by means of numerical experiments and then demonstrated by means of a case study of vehicle ownership in Montreal, Canada.     

Exploring the influence of built environment on tour-based commuter mode choice: A cross-classified multilevel modeling approach

Understanding travel behavior and its relationship to urban form is vital for the sustainable planning strategies aimed at automobile dependency reduction. The objective of this study is twofold. First, this research provides additional insights to examine the effects of built environment factors measured at both home location and workplace on tour-based mode choice behavior. Second, a cross-classified multilevel probit model using Bayesian approach is employed to accommodate the spatial context in which individuals make travel decisions. Using Washington, D.C. as our study area, the home-based work (Home-work) tour in the AM peak hours is used as the analysis unit. The empirical data was gathered from the Washington-Baltimore Regional Household Travel Survey 2007–2008. For parameter estimation, Bayesian estimation method integrating Markov Chain Monte Carlo (MCMC) sampling is adopted. Our findings confirmed the important role that the built environment at both home location and work ends plays in affecting commuter mode choice behavior. Meanwhile, a comparison of different model results shows that the cross-classified multilevel probit model offers significant improvements over the traditional probit model. The results are expected to give a better understanding on the relationship between the built environment and commuter mode choice behavior.     

矮塔斜拉桥0号块隔板空间应力分析

通过建立空间模型,对宁江松花江特大桥0号块隔板处复杂的应力的状况进行了计算分析,根据空间应力分析的结果进行了预应力钢束的配置,并以此指导普通钢筋的布置。这种计算方法能够较好的模拟0号块的空间受力性能,能够真实地反应结构的应力分布情况,对于同类桥梁的设计有一定的借鉴作用。     

SCGE modelling in cost-benefit analysis: The Dutch experience

Spatial computable general equilibrium (SCGE) models offer opportunities for computing wider economic effects in cost-benefit analysis (CBA) in a theoretically satisfactory way. This is important for the correct estimation of additional economic benefits and international relocation impacts. In the Netherlands, this potential has only been reached partly. Many different types of models are actually used, none of which yet covers all relevant markets. In CBAs carried out in recent years, ad hoc methods were used more often than models, let alone SCGE models. Moreover, the usual presentation of the model outcomes appears as a ‘black box’ to policy makers. There is much work to be done, in extending SCGE models to strengthen their empirical basis, and in improving the presentation of the outcomes.     

Land use/transport models and economic assessment

This paper discusses the economic assessment of policies using land use/transport models. It argues that conventional forms of assessment focussing only on transport changes can underestimate the economic benefits of a policy. The paper argues that the benefits need to be measured by the changes of prices at the end of a trip and not just by the changes in travel costs. Models that do not estimate the changes of prices at the end of a trip cannot properly assess the impact of a policy.The model used in this paper is based on the MEPLAN software and estimates the location of households and employment and the interaction between them. It also estimates the cost of living for households and the production costs for employment. With these costs, it is possible to calculate the wider economic benefits beyond transport.The paper illustrates the assessment of policies for the Cambridge sub-region involving investment in public transport, orbital highway and congestion charging policies. The results forecast by the model are assessed in terms of the conventional cost-benefit using traveller’s surplus as benefits and compared with a wider assessment measure of compensation variation. It demonstrates that the last measure encompasses the wider benefits associated with transport policies which are not taken into account in conventional cost-benefit analysis.     

Hub location in the South-Atlantic airline market: A spatial competition game

The paper analyzes the airlines’ hub location problem through a spatial competition game played in two stages. First, airlines sequentially choose the location of their hub and second, they compete offering direct or connecting services between each city-pair. Different outcomes in the first stage will affect competition in the second, and as a consequence, the market share that airlines can obtain.Given actual demand patterns, results of the model are applied to the South-Atlantic airline market. We study the subgame perfect equilibriums obtained as a result of competition in each city-pair to anticipate where airlines will probably locate their hubs once an “open skies” policy is adopted in this market.     

Microscopic simulation of transit operations: policy studies with the MISTRANSIT application programming interface

Abstract

Microscopic traffic simulators are the most advanced tools for representing the movement of vehicles on a transport network. However, the energy spent in traffic microsimulation has been mainly oriented to cars. Little interest has been devoted to more sophisticated models for simulating transit systems. Commercial software has some options to incorporate the operation of transit vehicles, but they are insufficient to properly consider a real public transport system. This paper develops an Application Programming Interface, called MIcroscopic Simulation of TRANSIT (MISTRANSIT), using the commercial microsimulator PARAllel MICroscopic Simulation. MISTRANSIT makes advances in three ways: public transport vehicles can have new characteristics; passengers are incorporated and traced as individual objects; and specific models represent the interaction between passengers and vehicles at stops. This paper presents the modelling approach as well as various experiments to illustrate the feasibility of MISTRANSIT for studying policy operations of transit systems.     

地震动空间变异性对大跨刚构桥地震反应的影响

导致地震动空间变异性的原因主要包括几何不相干性效应和行波效应。文章首先根据O.Ramadan等人提出的方法合成地震位移波,然后对沪蓉国道上龙潭河大桥进行了抗震时程计算,对地震动空间变异性各个主要因素的单独影响、综合影响分别进行了系统分析。计算结果表明,与一致激励相比较,地震动的空间变异性对龙潭河大桥在地震作用下的动力反应具有较大的影响。     

基于线性LRS与基于SRS的空间数据转换方法

本文主要研究基于线性LRS的空间数据到基于SRS的空间数据转换,并以二维空间为例进行讨论。提出采用Lagrange型插值、差商及Newton插值、差分及等距采样点插值及最小二乘逼近插值4种整体插值的数据转换方法,提出分段线性插值和分段多项式最小二乘拟合插值两种分段插值的数据转换方法,并分析所提出插值转换方法的优缺点。