The role of professional associations in shipping

This article is in three parts. The first covers the historical development of qualifying associations. The second covers the particular role of maritime institutions that include The Royal Institution of Naval Architects, The Institute of Marine Engineering Science and Technology and The Nautical Institute. The third and final section considers the future for maritime professional associations in the context of international shipping.     

Urban walkability considering pedestrians’ perceptions of the built environment: a 10-year review and a case study in a medium-sized city in Latin America

ABSTRACT

Numerous methodologies measuring walkability have been developed over the last years. This paper reviews the Walkability Index (WI) literature of the last decade (2009–2018) and highlights some limitations in the current approaches. Only a few studies have evaluated walkability in Latin America, mainly in big cities but not in medium and small-sized cities in the region, which present their own urbanisation dynamics, security issues, sidewalk invasion problems, and poor planning. Furthermore, most WIs in the literature use objective mesoscale variables to assess walkability in a given area. This paper contributes to filling these gaps by generating new evidence from a medium-sized city in Latin America to question if characteristics of the built environment encourage walking trips, as found in the literature, are transferable among regions. The study also proposes a novel index comprised of microscale and mesoscale built environment variables to assess walkability using virtual tools and considering users’ perceptions. The WI estimation relies on ranking probability models. The results of the case study suggest that subjective Security and Traffic Safety are the most crucial factors influencing walkability in these kind of cities, which is different from what is found in the literature from cities in developed countries where Sidewalk Condition and Attractiveness are the most important factors. Security appeared to be strongly associated with a subjective dimension, represented by the fear of crime or perceived risk for crime, instead of the actual occurrence of crimes. This result evidences the importance of the physical attributes of the real world and how they are captured, judged, and processed by pedestrians. Then, regional transferability of WIs needs to be done carefully. Finally, results in this paper highlight the importance of microscale built environment characteristics in the WI formulation in these cities. Results are in line with other research in some cities of the region, which found that microscale variables such as pavement quality and presence of obstacles on the sidewalks are relevant components to promote walkability.     

Assessing the CO2 impact of current and future rail track in the UK

This paper investigates the CO₂ impact of current and future UK rail track and estimates the material, process and transport emissions associated with construction, maintenance and end-of-life activities for designs at high and low traffic loads. Analysis shows that for current track configurations, track with concrete sleepers has the lowest CO₂ impact, followed by steel, hardwood and softwood. Several potential future rail track designs have been analysed including embedded rail and double and quadruple-headed rail. All future track designs have a lower impact than current designs, but this improvement is more marked at high traffic loads. Up to a 40% reduction in CO₂ impact could be achieved if the UK rail network was to move from conventional track design to a double-headed embedded rail design. Key levers for reducing the CO₂ impact of track are identified as service life extension, traffic load reduction and the selection of low impact track designs.     

A least absolute deviation critical decision path analysis with transport applications

This paper introduces a method that simultaneously analyzes travel variables from stated preferences that are measured under each of several different assumptions. The method uses least absolute deviation estimators and linear programming solutions and is flexible enough to permit inclusion of constraints for ordinal data and latent variables. Travel behavior is characterized by different indicators such as travel time, waiting time, mode choice and departure time. Consideration of different response variables simultaneously as part of a stated preference model requires a reclassification of variables as either endogenous or exogenous. This concept was introduced by the author as structural conjoint analysis earlier. Each endogenous variable may be defined as nominal, ordinal or cardinal and may be either explicitly measured or latent. Current econometric and psychometric techniques cannot accommodate this variety of data. The procedure is essentially a two-stage least absolute deviation simultaneous equation regression. The estimation technique is well known as are the various hypothesis tests. In the method each relationship between endogenous and exogenous variables is formulated separately carefully incorporating assumptions about each type of data. Thus there are different formulations for endogenous variables that are nominal and latent, ordinal and explicit, ordinal and latent, cardinal and explicit and cardinal and latent. Formulations for nominal latent, ordinal explicit and cardinal explicit variables were tested with simulated data for three separate hypothetical problems. Each problem consisted of at least two different types of variables and the technique was found to be able to reproduce the simulation function coefficients in virtually all cases.     

A linear programming approach to conjoint measurment and trade-off analysis

There has been increasing attention placed on decomposition techniques such as conjoint measurement and trade-off analysis. Existing algorithms for both approaches use non-linear estimation techniques. In this paper, a linear integration rule is proposed along with a linear programming algorithm which is used to estimate part-utilities by minimizing the sum of the absolute deviations subject to monotonicity constraints. The algorithm was tested on simulated data and empirically. It was found that the algorithm performed well, especially when data are consistent with initial assumptions.     

Measuring the influence of bus service quality on the perception of users

Encouraging the use of public transport is a key policy goal in many countries. Therefore, public transport should offer the level of quality that accommodates the demands of current users, and importantly, the desires of potential users. This study investigates the influence of the perceived quality of bus service on the perception of both current and potential users. The study draws upon data from 512 questionnaires distributed across Belfast City in the UK. The study utilises a binary logistic regression model to quantify the relationships between the perceived quality of 29 bus indicators (independent) and the perceptions of users towards the overall bus service (dependent). Eleven significant indicators are reported to have significant influence on the perception of users. These indicators are utilised to propose scenarios for optimising the quality of bus service with the perceptions of current and potential users.     

美国高铁困局

<正>2009年4月16日上午,奥巴马总统在副总统和交通部长的陪同下,宣布将从经济复苏计划(又称"经济刺激计划")中拨出80亿美元,用于兴建横贯美国的高速铁路干线,此外,未来连续5年里,每年都会另投资10亿美元用于高铁项目。"想象一下吧,以超过100英里的时速呼啸穿过大大小小的城镇,起点站离家门口不过几步路,终点站距目的地不过几个街区之遥。"奥巴马说道,"这是一项多     

Using AHP to measure the perception gap between current and potential users of bus services

Abstract

This study develops a multicriteria evaluation of user perception towards bus transit services and measures the gap in the perceptions held by current and potential users. A review of the transport quality literature indicates that both preference and satisfaction measures have been implemented to provide a comprehensive perception-based evaluation of bus quality. Although attempts have been made to evaluate user perception through a separate analysis of each (preference and/or satisfaction), the application of multicriteria quality measures are limited. A multicriteria quality measure not only offers more than just information on the daily experience of users but also knowledge of the internal process of quality evaluation (drivers/barriers). The multicriteria measure utilises the data of 512 questionnaires, whereby user perceptions were expressed through judgments of importance and satisfaction based on a set of 29 quality indicators classified into six attributes. Firstly, the study develops analytical hierarchy process (AHP) models to measure user preference. Secondly, a weighted perception index (WPI) of both preference and satisfaction is developed through a multicriteria model. Finally, multivariate analysis of variance (MANOVA) is conducted to identify the level of variation in the perception of both current and potential users towards bus service quality. The results show that although both current and potential users place a higher importance towards the same indicators, they do not share the same pattern of preferences (values and/or order). In addition, the study found that the interaction between preferences and satisfaction generated new patterns of subjective evaluation, and that these patterns vary significantly by user category.     

高精度连续函数对边坡岩体分级的修正

为克服SMR(边坡岩体分级)法已有连续函数修正拟合精度不高的缺点,基于离差平方和最小原理,采用新的连续函数对"表格式评分"的SMR法进行了修正,给出了点荷载强度、单轴抗压强度、岩体质量指标、不连续面间距、不连续面产状调整系数、不连续面延伸长度、张开度及充填物厚度评分的连续函数.用新提出的修正SMR的连续函数对水电、矿山、公路等57个边坡岩体进行了稳定性分级,剩余标准差为2.180,相关系数为0.996 7,比其他修正SMR法更接近表格式SMR法的评分结果.     

Rural transport – Valuing the mobility of older people

This paper describes a series of focus groups that were undertaken in the Republic of Ireland and Northern Ireland to examine the challenges faced by older people in rural Ireland when trying to make trips. The paper outlines transport policy in both Northern Ireland and the Republic of Ireland and describes the activity patterns of older trip makers and the modes they use. It also discusses some of the contrasts between challenges faced by older men and older women. Both older men and older women experience a shrinking in activity spaces and activity participation when older. Older women are less likely to drive and to own a car and so are seriously impacted by loss of a spouse in terms of their unmet travel needs. However, older men also experience difficulties: the alternatives that are available (such as community transport schemes) provide trips and services that are more attractive to women. In addition, the car dependent lifestyles of men throughout their adult lives seems to make them less prepared for life without a car than older women.