A combined destination and route choice model for a bicycle sharing system

This paper studies the supply variables that influence the destination and route choices of users of a bicycle sharing system in the Chilean city of Santiago. A combined trip demand logit model is developed whose explanatory variables represent attributes relating to the topology of the possible routes and other characteristics such as the presence of bikeways, bus service and controlled intersections. The data for the explanatory variables and system users were collected through field surveys of the routes and interviews conducted at the system stations. The results of the model show that proximity to stops on the Santiago Metro and the existence of bikeways are the main factors influencing destination and route choices. Also indicated by the model estimates are gender differences, a preference for tree-lined routes and an avoidance of routes with bus services. Finally, the outcomes reveal considerable potential for the integration of bicycle sharing systems with Metro transit.     

Effects of task complexity and time pressure on activity-travel choices: heteroscedastic logit model and activity-travel simulator experiment

This paper derives, estimates and applies a discrete choice model of activity-travel behaviour that accommodates potential effects of task complexity and time pressure on decision-making. To the best of our knowledge, this is the first time that both factors (task complexity and time pressure) are jointly captured in a discrete choice model. More specifically, our heteroscedastic logit model captures potential impacts of task complexity and time pressure through the scale of the utility of activity-travel options. We collect data using a novel activity-travel simulator experiment that has been specifically designed with the aim of testing our model. Results are in line with expectations, in that higher levels of task complexity and time pressure are found to result in a smaller scale of utility. In other words, higher levels of task complexity and time pressure lead to more random choice behaviour and as a consequence to less pronounced differences in choice probabilities between alternatives. An empirical illustration suggests that choice probability-differences between models that do and those that do not capture these effects, can be very substantial; this in turn suggests that failing to capture the effects of task complexity and time pressure in discrete choice models of activity travel decision-making might lead to serious bias in forecasts of the effects of transport policies.     

A method to evaluate equitable accessibility: combining ethical theories and accessibility-based approaches

In this paper, we present the case that traditional transport appraisal methods do not sufficiently capture the social dimensions of mobility and accessibility. However, understanding this is highly relevant for policymakers to understand the impacts of their transport decisions. These dimensions include the distribution of mobility and accessibility levels over particular areas or for specific population groups, as well as how this may affect various social outcomes, including their levels of participation, social inclusion and community cohesion. In response, we propose a method to assess the socially relevant accessibility impacts (SRAIs) of policies in some of these key dimensions. The method combines the use of underlying ethics principles, more specifically the theories of egalitarianism and sufficientarianism, in combination with accessibility-based analysis and the Lorenz curve and Gini index. We then demonstrate the method in a case study example. Our suggestion is that policymakers can use these ethical perspectives to determine the equity of their policies decisions and to set minimum standards for local transport delivery. This will help them to become more confident in the development and adoption of new decision frameworks that promote accessibility over mobility and which also disaggregate the costs and benefits of transport policies over particular areas or for specific under-served population groups.     

The digital revolution and worthwhile use of travel time: implications for appraisal and forecasting

Savings in travel time and more specifically their monetary value typically constitute the main benefit to justify major investment in transport schemes. However, worthwhile use of travel time is an increasingly prominent phenomenon of the digital age. Accordingly, questions are increasingly being asked regarding whether values of time used by countries around the world based on their appraisal approaches are too high. This paper offers the most comprehensive examination of our theoretical and empirical understandings of international appraisal approaches and how they account for worthwhile use of travel time. It combines the economics perspective with wider social science insight and reaches the conclusion that past revolutions in transport that have made longer and quicker journeys possible are now joined by a digital revolution that is reducing the disutility of travel time. This revolution offers potential economic benefit that comes at a fraction of the cost of major investments in transport that are predicated on saving travel time. The paper highlights the challenges faced in both current and indeed potential alternative future appraisal approaches. Such challenges are rooted in the difficulty of measuring time use and productivity with sufficient accuracy and over time to credibly account for how travel time factors into the economic outcomes from social and working practices in the knowledge economy. There is a need for further research to: establish how improvements in the opportunities for and the quality of worthwhile use of travel time impact on the valuation of travel time savings for non-business travel; improve our understanding of how productive use of time impacts on the valuation of time savings for business travellers; and estimate how these factors have impacted on the demand for different modes of travel.     

驾驶特性对交通安全的影响分析

本文基于对人类行为模式的研究,并以此作为参考,将驾驶员的信息处理过程划分为感知、判断、操纵三个阶段。分析感知特性、判断特性、操作特性对交通安全的影响。     

山区高速公路长大下坡路段避险车道 设置位置研究

本文在分析了避险车道现状问题和安全影响因素的基础上,通过货车在雅西高速公路上的制动鼓温度变化实车试验,建立货车在山区高速公路长大下坡路段行驶时的制动鼓温度变化模型,然后在试验的基础上建立一套适用于山区高速公路的避险车道设置位置理论计算方法,以此来确定避险车道的设置位置和设置间距.     

汽车机械变速器润滑油温升测试系统开发

为测试微型车机械变速器最高工作油温,设计了共直流母线能量回馈电封闭式变速器温升检测试验台。介绍了该试验台的结构、测试原理、通信方式、数据采集过程以及上、下位机的编程软件。温升检测结果表明,在高转速、无外界强制散热的情况下,该试验台可准确测试变速器工作油温,检测效率高,且负载发电机在温升试验空转时可以实现发电功能。     

Integral transform solution for fluid force investigation of a flexible circular cylinder subject to vortex-induced vibrations

In the present paper, fluid force distribution of a long flexible cylinder subject to vortex-induced vibrations is investigated by Generalized Integral Transform Technique (GITT). This method is using experimental response data as input, and then implementing GITT to transfer the governing differential equations to ordinary differential equations. Therefore, the selection of truncation order could be analyzed to avoid the error induced by the high-mode response. Once each mode contribution of fluid force is obtained, the analytical inversion transfer recovers the fluid force. An experiment was carried out in a towing tank and the experimental response was accurately measured and used as input, then GITT was performed to calculate the fluid force distribution of the long flexible cylinder. The comparison between the numerical results from GITT and the experimental results from load cell verified the capability and availability of the proposed method. If one can use this method for lower modes, then one certainly can extend the method for higher modes. Two experimental cases from the literature were evaluated and good agreement was obtained based on the spatio-temporal evolutions of the lift coefficient and the mode numbers. Since this method is easy to implement, it could be an alternative method to investigate fluid force of such slender structures.     

Experimental study on piston- and sloshing- mode moonpool resonances

An experimental study was performed on the piston- and sloshing-mode moonpool resonances of offshore structures. Two different geometries were considered to investigate the flow characteristics in a plain moonpool and a moonpool with a cofferdam. To examine the efficiency of a cofferdam for reducing the flow in a moonpool, three cofferdam geometries were tested. The plain moonpool presented violent flows as a result of the piston- and sloshing-mode resonances. However, the moonpool with the cofferdam introduced violent sloshing waves instead of the ascent and descent of the water column in the piston-mode moonpool resonance. Among three different cofferdam geometries, the model with a right triangle facing to the left on the top of the cofferdam was most effective in reducing the flow in the moonpool when compared with the other models.