Innovative strategies for urban car-sharing systems and a simulator to assess their performance

In this paper, three innovative car-sharing systems for urban areas are proposed, based on fleets of individual intelligent vehicles with three service characteristics: instant access, open-ended reservations and one-way trips. These features provide high flexibility but create an uneven distribution of vehicles among stations. Therefore, relocation of vehicles must be performed. Three different system procedures are proposed: in the first system, relocations are performed by users; in the other two, vehicles relocate automatically, thanks to their automation. In the first two systems, vehicles are accessible only at stations, whereas in the third they are also accessible along roads. In order to provide transport managers with a tool to test systems in different realities, an object-oriented simulator is developed. The simulation provides outputs of system performance, in terms of user waiting times and system efficiency. The proposed systems are simulated for the city of Genoa, in Italy, and a comparative analysis is presented.     

Impact of ICT access on personal activity space and greenhouse gas production: evidence from Quebec City, Canada

This paper presents an approach to investigating the impact of information and communication technologies (ICTs) on travel behaviour and its environmental effects. The paper focuses on the spatial dispersion of out-of-home activities and travel (activity space) and greenhouse gas emissions (GHGs) at the level of the individual. An original method, combining spatial analysis in a geographic information system with advanced regression techniques, is proposed to explore these potentially complex relationships in the case of access to mobile phones and the internet, while taking into account the influence of socio-economics and built environment factors. The proposed methodology is tested using a 7-day activity-based survey in Quebec City in 2003?C2004, a juncture of particular interest because these ICTs had recently crossed the threshold of 40?% (mobile phone) and 60?% (home-based internet) penetration at the time. The study period also largely pre-dates the era of mobile internet access. Among other results, socio-demographic factors were found to significantly affect both ICT access and travel out-comes. The built environment, represented by neighbourhood typologies, also played an important role. However, it was found that after controlling for the self-selection effect, built environment and socio-demographics, those who had a mobile phone available produced 30?% more GHGs during the observed week than those who did not. This higher level of GHG pro-duction was accompanied by a 12?% higher measure of activity dispersion. On the other hand, having internet access at home was associated with lower GHGs (?19?%) and lesser activity dispersion (?25?%). Possibly, mobile phones enable individuals to cover more space and produce more emissions, while the internet provides opportunities to stay at home or avoid motorized travel thus reducing emissions. The estimated effects of having a mobile phone were not only negative but also larger in magnitude from the environmental point of view than those of fixed internet access. However, the results of this study also suggest that access to mobile phones and internet may have substantial and compensatory effects at the individual level that are undetected when using model structures that do not take into account that unobserved factors may influence both ICT choices and travel outcomes.     

Reduced dwell times resulting from train–platform improvements: the costs and benefits of improving passenger accessibility to metro trains

Abstract

This paper examines whether a dwell time reduction on a high-intensity metro service, as a result of a series of accessibility enhancements, can contribute to an increased level of service and accessible public transport for passengers together with a reduction in costs for the operator. Actual train operation data were collected by on-site observations and from London Underground Ltd. A simple simulation is built to represent the effect on the overall cycle times of trains if certain parameters (e.g. dwell time) are changed. Four models are developed, concerning: (1) step height between train and platform, (2) an assumption of passenger service time to be no longer than 20 s, (3) door width and (4) the combination of step height and door width. From the application of the models it appears that the fourth model provides the highest reduction in dwell time and diminishes the overall cycle times of trains. However, it is the most expensive to implement as it requires work to raise platforms and the purchase of new rolling stock.     

What determines commute time choices? A structural equation modelling approach

Abstract

Many researchers have been attracted by the phenomenon of constant travel time, and the time spent on travel has been an important indicator of understanding travellers’ behaviours. This paper is based on a survey conducted in a university in London which includes both objective and subjective variables in relation to commute time and some demographic characteristics. Two conceptual structural models are examined in order to explore the factors determining travellers’ choices. Results of the analysis reveal some interesting relationships: (1) a positive relationship between age and commute time; (2) females are more likely to read or listen to music during their journeys, and their ideal commute time (ICT) and current commute time (CCT) generally tend to be longer; (3) academic staff tend to have the habit of working during their commute, administrative staff tend to commute longer while students tend to spend a shorter time commuting; (4) normally, a habit while travelling is significantly associated with CCT; those with a habit of reading or working during their commute journey tend to have longer commute times and (5) the relationship between CCT and commuters’ ICT and tolerable commute time is positive; both hypothesised causal relationships are significant so that a loop is formed between subjective and objective variables, and thus a dynamic modelling process could be envisaged as temporal sequences of those variables.     

A micro-level approach to measuring the accessibility of footways for wheelchair users using the Capability Model

There are a growing number of people with mobility impairments who use wheelchairs to get around the built environment. This number is likely to increase in the future due to an increasingly ageing population combined with advances in medical technology which help to overcome some of the barriers to access that have hitherto prevented people from leading as full a life as they would have liked. Footways form an integral part of the transport network and therefore it is essential they can be accessed by all people. Currently, however, there is no well-defined method to measure the accessibility of footways for wheelchair users. One aspect of a footway is the crossfall – the transverse gradient designed to facilitate surface water drainage – which adds to a wheelchair user's difficulty when progressing along the footway. This paper first reviews previous research on measuring the effect of crossfalls on wheelchair accessibility, highlighting the need for a new approach. It then proposes the Capability Model as a starting point for this new approach. The model is updated and populated with an initial capability set chosen to measure footway accessibility across footways with three different crossfall gradients (0%, 2.5% and 4%). The focus is on the physical work provided by the user to the wheelchair in order to keep it travelling in a straight line. It is shown that in order to travel in a straight line when a footway is flat only a single principal capability is required: the ability to produce sufficient force over the required distance to overcome the inertia and rolling resistance and keep the wheelchair moving at the chosen velocity. When a positive crossfall gradient is introduced a second capability is required: the ability to apply different levels of force to the left and right sides of the wheelchair. It is concluded that it is possible to measure these two capabilities and these provide a good insight into the effect of crossfalls on footway accessibility for wheelchair users.     

Train design features affecting boarding and alighting of passengers

Accurately predicting train dwell time is critical to running an effective and efficient service. With high‐density passenger services, large numbers of passengers must be able to board and alight the train quickly – and within scheduled dwell times. Using a specially constructed train mock‐up in a pedestrian movement laboratory, the experiments outlined in this paper examine the impact of train carriage design factors such as door width, seat type, platform edge doors and horizontal gap on the time taken by passengers to board and alight. The findings illustrate that the effectiveness of design features depends on whether there are a majority of passengers boarding or alighting. An optimum door width should be between 1.7 and 1.8 m. The use of a central pole and platform edge doors produced no major effects, but a 200 mm horizontal gap could increase the movement of passengers. There is no clear effect of the type of seats and neither the standbacks between 50, 300 and 500 mm. Further research will look for the relationship between the dwell time and the characteristics of passengers such as personal space. Copyright © 2017 John Wiley & Sons, Ltd.     

Capabilities and Radicalism: Engineering Accessibility in the 21st century

Abstract

Engineering bridges the gap between, on the one hand, that mix of philosophy and politics that we call policy and, on the other, the physical implementation of the means to put policy into practice. Starting with a brief outline of the nature of accessibility, why it is important and how in some cases a person might be disabled by a lack of accessibility, this article – based on the author's Inaugural Lecture given at University College London in February 2005 – turns to consider how a person's needs challenge their capabilities (i.e. what they can do) and considers a radical approach to understanding people's capabilities in the implementation process. Next, the formation of policy intentions in order to permit, encourage and implement the engineering of appropriate solutions is discussed and conclusions drawn about how this affects work in the transport domain. Perhaps we need to look at the world in a different way before we can make it a better place.     

Symbolic transport choice across national cultures: theoretical considerations for research design

A recently empirically isolated latent variable in transport choice is symbolism, which examines what people believe their transport choices say to others about them and how they are judged in a social context. Whilst it is well established that symbolism differs vertically across different socio-economic groups within a country, very little work has been done on how symbolism in transport may differ between similar individuals across nations as a function of national cultural values, and how this may manifest itself in transport choices. If significant differences were to be found then this could have impacts for transport policy formulation and transfer. This paper explores and discusses these issues and concludes that the initial goal of any research into symbolic transport choices across cultures is theoretical fertility, and this is best achieved by adopting Lakatosian research programmes, using theory-driven thematic analysis to develop theoretical models for testing.