公交线网优化新技术的应用研究

针对现有公交线网优化研究模型求解复杂、可操作性不强的现状,提出了一种新的公交线网优化方法：从分析乘客对线网的需求意愿入手,获取线网优化要重点解决的问题,在此基础上提出优化策略。建立平衡乘客及公交运营企业利益的系统成本最优模型。最后以济南为例,验证方法的可操作性和优化结果的可实施性。     

Generating twins to build weekly time use data from multiple single day OD surveys

Origin-Destination surveys, which are regularly conducted in many cities (to calibrate transport models), contain indirect information on individual time use that can be recovered through the declared trip purpose. Although this data source is very rich, it has two limitations for the calibration of time use models: the level of disaggregation regarding time use is constrained by the definition of trip purposes, and the information gathered on different time periods is usually obtained from different individuals. In this paper we propose a new method to overcome the second limitation, transforming the original daily observations into individual-weeks. For every working day observation we build Saturday and Sunday “twins” as a convex combination of observed weekend individuals such that the distance between the attributes of the working day individual and the synthetic twin is minimized. We applied this procedure to the Santiago OD survey, and generated a database of weekly observations particularly rich for model calibration and segmentation.     

Public regulation and passengers importance in port infrastructure costs

Because ports are conceived and designed mainly to be the transfer point of various types of freight, passengers tend to be forgotten in the analysis of port costs. In this paper first we investigate the importance of passengers in port infrastructure costs by means of a multi-output cost function estimated from 20 annual observations (1986-2005) for 26 Spanish Port Authorities. Results show that, although a passenger weights on average less than one tenth of a ton, he or she represents as much as two tons of solid bulk and about three tons of containerized general cargo in terms of marginal costs. Secondly, we compare the marginal costs of different cargoes with their price caps established by law. Results suggest that some type of second best pricing is induced by present regulation.     

Integrating short turning and deadheading in the optimization of transit services

Urban transit demand exhibits peaks in time and space, which can be efficiently served by means of different fleets, increasing frequencies in those groups of stops with larger passenger inflow. In this paper we develop a model that combines short turning and deadheading in an integrated strategy for a single transit line, where the optimization variables are both of a continuous and discrete nature: frequencies within and outside the high demand zone, vehicle capacities, and those stations where the strategy begins and ends. We show that closed solutions can be obtained for frequencies in some cases, which resembles the classical “square root rule”. Unlike the existing literature that compares different strategies with a given normal operation (no strategy - single frequency), we use an optimized base case, in order to assess the potential benefits of the integrated strategy on a fair basis. We found that the integrated strategy can be justified in many cases with mixed load patterns, where unbalances within and between directions are observed. In general, the short turning strategy may yield large benefits in terms of total cost reductions, while low benefits are associated with deadheading, due to the extra cost of running empty vehicles in some sections.     

Multioutput analysis of cargo handling firms: An application to a Spanish port

Cargo handling in ports is a multioutput activity, as freight can arrive in many forms such as containers, bulk, rolling stock, or non-containerised general cargo. In this paper, the operation of cargo handling firms in a Spanish port is analysed through the estimation of a multioutput cost model that uses monthly data on three representative firms located at the Las Palmas port. This permits the calculation of product specific marginal costs, economies of scale (general and by firm) and economies of scope, which help identifying optimal pricing policies and the potential cost advantages of increasing production.     

Modelling bicycle use intention: the role of perceptions

Users’ perceptions are identified as key elements to understand bicycle use, whose election cannot be explained with usual mobility variables and socio-economic characteristics. A hybrid model is proposed to model the intention of bicycle use; it combines a structural equations model that captures intentions and a choice model. The framework is applied to a case of a university campus in Madrid that is studying a new internal bike system. Results show that four latent variables (convenience, pro-bike, physical determinants and external restrictions) help explaining intention to use bike, representing a number of factors that are linked to individual perceptions.     

绿色交通相关问题概述

首先介绍了绿色交通的目的,在提出绿色交通系统层级的基础上,分别从步行交通、自行车交通、公共交通3个方面具体分析了绿色交通现状存在的问题及改善措施.之后,从限制小汽车的使用角度出发,阐述了拥挤收费的概念和近期的实践,并以新加坡和伦敦为例,重点分析了拥堵收费具体的作法及所取得的成效.最后,呼吁举办无车日活动,以更好地促进绿色交通发展.     

The effect of financial constraints on the optimal design of public transport services

Recent experience with the design of bus services in Santiago, Chile, seems to confirm Jansson's (1980) assertion regarding observed planned bus frequency and size being too low and too large, respectively. We offer an explanation based upon the relation between cost coverage, pricing and optimal design variables. We recall that average social cost decreases with patronage, which generates an optimal monetary fare below the average operators' cost, inducing an optimal subsidy. Then we compare optimal frequency and bus size—those that minimize total social costs—with those that minimize operators' costs only. We show that an active constraint on operators' expenses is equivalent to diminish the value of users' time in the optimal design problem. Inserting this property back in the optimal pricing scheme, we conclude that a self-financial constraint, if active, always provokes an inferior solution, a smaller frequency and, under some circumstances, larger than optimal buses.

A joint time-assignment and expenditure-allocation model: value of leisure and value of time assigned to travel for specific population segments

Transportation - Based on a time-use model with a sound theoretical basis and carefully collected data for Austria, the value of leisure (VoL) for different population segments has been estimated....