The advantages of a high density,mixed land use,linear urban development

This paper describes the land use and transport characteristics of a strip of urban development located along the northern shore of Hong Kong Island. The strip of land, with an area of 22.5 sq. km, is 17 km long and has an average width of 1.3 km. It has a population of approximately one million and provides over 700,000 jobs. Despite its small size, it accommodates the CBD, residential districts, shopping complexes as well as most of the civic/institutional facilities that a city needs. Its urban form is linear not by design but by default – the topography of the area has constrained the development from spreading sideways. Surprisingly however, apart from economy in land utilization, it is considered to possess three other good qualities: high accessibility enjoyed by residents; few roads and commercially viable public transport. Its travel characteristics are analyzed, using results of a home interview survey conducted by the Government in 1992. In addition, various statistics published by the Government and public transport authorities are also used in the analysis.     

How big should transit be? Evidence on the benefits of reorganization from the San Francisco Bay Area

This paper studies whether the many public urban transit providers in the San Francisco Bay Area could realize cost economies by consolidating into larger systems. In this discussion, any benefits of rationalization are excluded, since these could be achieved without organizational changes.The results support the formation of larger multi-modal systems in the Bay Area. But care must be taken in selecting the candidates for reorganization, and a broad-brush approach could result in important lost opportunities for cost reduction. But if these economies are taken into account, and transit grows in the right directions, the benefits could be substantial.     

Meta-analysis of UK values of travel time: An update

Numerous travel demand studies have been carried out over the past five decades, many of which produce estimates of the value of travel time. This includes a rich body of largely unpublished evidence, which can provide valuable insights into the impact of variables such as GDP, travel distance, purpose and mode on this critical parameter for transport modelling and appraisal. The work reported in this paper updates and extends our previous meta-analyses of UK values of time ( [Wardman, 1998], [Wardman, 2001a] and [Wardman, 2004]) by adding recent studies and widening the range of explanatory variables included. Our current research covers 226 studies carried out between 1960 and 2008, yielding a total of 1749 valuations (a 50% increase relative to our previous work) and making this the largest data set of its kind to the best of our knowledge. This is also the most comprehensive study to date of parameters other than in-vehicle time and includes valuations of walk, wait, headway, congested, free flow, late, departure time shift and search time. Exploratory analysis of the data set provides interesting insights into methodological trends in travel demand modelling.For each valuation, over thirty quantitative and categorical variables were recorded and then included in a multivariate regression model to explain variations in the value of time. A large number of statistically significant effects were obtained from this meta-analysis, some of which are in marked contrast with, or not present in, our previous work. One finding that stands out is that the estimated elasticity of the value of time with respect to GDP per capita is 0.9 and highly significant, a much closer correspondence to the widely used convention of a unit income elasticity over time than we have previously obtained. The ratio between walk and wait time and in-vehicle time was found to be substantially lower than the commonly used value of two. We also found large and significant differences between the results from studies based on different types of Stated Preference survey presentation. Other important effects include variations by mode used, mode valued, travel purpose, attribute type and distance. It is envisaged that the results are of direct relevance in the British context, as inputs to appraisal or for benchmarking, whilst the methodological implications are of broader interest and the results, in terms of time equivalents and variations in values of time, can be transferred to other contexts.     

Forecasting ridership for a metropolitan transit authority

The recent volatility in gasoline prices and the economic downturn have made the management of public transportation systems particularly challenging. Accurate forecasts of ridership are necessary for the planning and operation of transit services. In this paper, monthly ridership of the Metropolitan Tulsa Transit Authority is analyzed to identify the relevant factors that influence transit use. Alternative forecasting models are also developed and evaluated based on these factors—using regression analysis (with autoregressive error correction), neural networks, and ARIMA models—to predict transit ridership. It is found that a simple combination of these forecasting methodologies yields greater forecast accuracy than the individual models separately. Finally, a scenario analysis is conducted to assess the impact of transit policies on long-term ridership.     

Weather variability and travel behaviour – what we know and what we do not know

Given that severe weather conditions are becoming more frequent, it is important to understand the influence of weather on an individual’s daily activity-travel pattern. While some previously rare events are becoming more common, such as heavy rain, unpredicted snow, higher temperatures, it is still largely unknown how individuals will change and adapt their travel patterns in future climate conditions. Because of this concern, the number of research studies on weather and travel behaviour has increased in recent decades. Most of these empirical studies, however, have not used a cost–benefit analysis (CBA) framework, which serves as the the main tool for policy evaluation and project selection by stakeholders. This study summarises the existing findings regarding relationships between weather variability and travel behaviour, and critically assesses the methodological issues in these studies. Several further research directions are suggested to bridge the gap between empirical evidence and current practices in CBA.     

An empirical analysis of freight transport traffic modes in Brazil, 1996–2012

This paper analyses the performance of freight transportation modes in Brazil – namely air, water, rail and road – from February 1996 to August 2012 by investigating their long memory properties using fractional integration and autoregressive models on monthly tonnage data. Two important features are analysed: the degree of dependence of transportation traffic across time and its seasonal structure over the period. Furthermore, the stability of parameters across the sample period is investigated, incorporating potential structural breaks in the data, which describe discontinuity in freight transportation traffic. Some policy implications are derived.     

Fatigue analysis for a multi-lap spot welded joint of high strength steel using quasi static tensile-shear test

The welding quality of spot weldment is an important factor that significantly affects the strength, stiffness, safety, and other performance characteristics of vehicles. Therefore, quality control and fatigue life evaluation of spot weldment are necessary processes. This paper presents a method for determining the fatigue life of multi-lap spot weldment of a high strength steel sheet. In this method, the fatigue life is estimated using the lethargy coefficient, which is the total defect coefficient according to rupture stress and time obtained by the quasi static tensile-shear test. The DC potential drop method was used to check initiation and propagation of cracks in addition to the test. Also, in this study, we modified the lethargy coefficient by using the welding current. Furthermore, we define a specific lapping constant, which is a characteristic constant of 2 or 3 lap weldments. The fatigue life obtained by the fatigue estimate equation, which contains a specific lapping constant was compared and verified with an experimental value. Finally we analyzed the relation of lap number, welding current and fatigue life. This method can save processing time and cost for predicting the life cycle of a structure.     

Effects of the fuel injection ratio on the emission and combustion performances of the partially premixed charge compression ignition combustion engine applied with the split injection method

Currently, due to the severity of world-wide air pollution by substances emitted from vehicles, emission control is being enforced more strictly, and it is expected that the regulation requirements for emission will become even more severe. A new concept combustion technology that can reduce the Nitrogen oxides (NOx) and PM in relation to combustion is urgently required. As a core combustion technology among new combustion technologies for the next generation engine, the homogenous charge compression ignition (HCCI) is expanding its application range by adopting a multiple combustion mode, a catalyst, direct fuel injection and partially premixed charge compression ignition combustion using the split injection method. This paper used a split injection method in order to apply the partially premixed charge compression ignition combustion method without significantly altering engine specifications of the multiple combustion mode and practicality by referring to the results of studies on the HCCI engine. Furthermore, the effects of the ratio of the fuel injection amount on split injection are investigated. From the test results, the adequate combination of the ratio of the fuel injection amount for the split injection method has some benefit on exhaust and fuel economy performance in a naturally aspirated single cylinder diesel engine.     

Role of steering wheel feedback on driver performance: driving simulator and modeling analysis

When driving in curves, how do drivers use the force appearing on the steering wheel? As it carries information related to lateral acceleration, this force could be necessary for drivers to tune their internal model of vehicle dynamics; alternatively, being opposed to the drivers' efforts, it could just help them stabilize the steering wheel position. To assess these two hypotheses, we designed an experiment on a motion-based driving simulator. The steering characteristics of the vehicle were modified in the course of driving, unknown to drivers. Results obtained with standard drivers showed a surprisingly wide range of adaptation, except for exaggerated modifications of the steering force feedback. A two-level driver model, combining a preview of vehicle dynamics and a neuromuscular steering control, reproduces these experimental results qualitatively and indicates that adaptation occurs at the haptic level rather than in the internal model of vehicle dynamics. This effect is related to other theories on the manual control of dynamics systems, wherein force feedback characteristics are abstracted at the position control level. This research also illustrates the use of driving simulation for the study of driver behavior and future intelligent steering assistance systems.