Scott Le Vine

Factors Associated With Young Adults Delaying and Forgoing Driving Licenses: Results From Britain

Objective: To identify the reasons that young adults (age 17–29) in Britain delay or forgo driving license acquisition. Methods: Using year 2010 British National Travel Survey microdata, we first analyze self-reported reasons (including their prioritisation) for not holding a full car driving license and then estimate a logistic regression model for license-holding to investigate additional factors, several of which extend from previous studies. This study also employs a novel segmentation approach to analyze the sets of reasons that individual young adults cite for not driving. Results: These results show that, despite the lack of a graduated driving license system at present, many young adults indicate that issues associated with the driving license acquisition process are the main reason they do not hold a full driving license. About 3 in 10 young adults can be interpreted as not viewing driving as a priority, though half of those without a license are either learning to drive or are deterred principally by the cost of learning. We calculate that after their 17th birthday (the age of eligibility for a full driving license) young adults spend a mean of 1.7 years learning to drive. Young adults citing the costs of insurance or car purchase are likely to cite them as secondary rather than the main reason for not driving, whereas those citing physical/health difficulties are very likely to cite this as the main reason they do not drive. Two distinct groups of young people are identified that both indicate that costs deter them from driving—one group that is less well off financially and that indicates that costs alone are the primary deterrent and one that reports that other reasons also apply and is better off. Status as an international migrant was found to be an important factor, net of confounding variables, for identifying that a young adult in Britain does not hold a driving license. Further research is needed to understand the relative saliency of plausible causal mechanisms for this finding. We also report that both personal income and household income are independently positively associated with license-holding but that (intuitively) the relationship of license holding with a young adults own personal income is the much stronger of the two. Conclusions: On the basis of these findings, it can be concluded that a number of previously underappreciated factors appear to be linked with young British adults not acquiring a driving license.

A Tenuous Result: Re-analysis of the Link Between Internet Usage and Young Adults’ Driving License Holding. Comments on “Recent Changes in the Age Composition of Drivers in 15 Countries”

Sivak and Schoettle (2011) reported a cross-national comparison of trends in driving licencing rates among adults of different ages. The majority of the paper was devoted to presenting descriptive results. It was reported that in 8 of the 15 countries studied, there has been a decrease in driving licencing rates among young people (aged 20–24) and a corresponding increase among older adults, and in the other 7 countries there has been an increase in licencing rates among adults of all ages. Because crash rates vary strongly with driver age, there are potentially large implications for future trends in road casualties. The descriptive results are sound. The abstract states, however, that the primary implication of the study is based on a multivariate analysis: “The results of the analysis are consistent with the hypothesis that access to virtual contact reduces the need for actual contact among young people” (p. 126). This finding arises from the parameters estimated by linear regression with the various countries as the cases. Ten candidate country-level descriptors were used as independent variables. Stepwise linear regression with backward elimination, a data mining technique, was used to search among the 1,023 possible specifications. Four independent variables were retained in the preferred specification (gross national income at purchasing power parity, median age of the population, percentage of the population living in settlements of more than 1 million people, and number of Internet users per 100 people). Though the estimated regression parameters were not reported, it was reported that the number of Internet users per 100 (all age) population has a negative association with young adults’ rate of license holding with a t-statistic of −3.33. This result forms the basis for what is reported as the main implication of the study, namely, the negative association between Internet usage and young adults’ license holding.

Design of a Strategic-Tactical Stated-Choice Survey Methodology Using a Constructed Avatar

This paper presents findings from a small-sample qualitative study on peoples activity travel behavior in the presence or absence of carsharing. A carsharing service provides its subscribers with short-term access to a fleet of shared cars. In previous research, subscribers have reported distinctive travel patterns, such as more car usage by subscribers than by non–car owners but less than by car owners. Reflexive techniques were used in which interviewees adapted a week of their recent activity travel behavior in response to stimuli. Findings from this study informed the design of a stated-choice survey that addressed three principal forms of complexity: (a) strategic-tactical choice situations, (b) situations in which respondents might select multiple interacting options in a single choice situation, and (c) situations in which sufficient knowledge of the individual survey respondent to tailor such a complex choice situation could not feasibly be gathered during a single interview. In the proposed design, the respondent indicates a strategic choice of which methods of travel to make available for use given a set of representative out-of-home activities. Accessibility to each activity by various means of travel is generated by using empirical distributions from Britains National Travel Survey data sets to maximize plausibility of the information presented to respondents. An avatar (a virtual character for purposes of the survey) is constructed for each respondent on the basis of a small set of self-reported demographic characteristics. The use of multiday activity travel diaries would ideally involve multiple points of contact with each respondent at substantial cost. Therefore, an alternative method involving a single interview per respondent was sought.

The Contribution of Benefit-in-Kind Taxation Policy in Britain to the 'Peak Car' Phenomenon

Car use per person has historically grown year-on-year in Great Britain since the 1950s, with minor exceptions during fuel crises and times of economic recession. The ‘Peak Car’ hypothesis proposes that this historical trend no longer applies. The British National Travel Survey provides evidence of such an aggregate levelling off in car mileage per person since the mid-1990s, but further analysis shows that this is the result of counter trends netting out: in particular, a reduction in per capita male driving mileage being offset by a corresponding increase in female car driving mileage. A major contributory factor to the decline in male car use has been a sharp reduction in average company car mileage per person. This paper investigates this aspect in more detail. Use of company cars fell sharply in Britain from the 1990s up to the 2008 recession. Over the same period, taxation policy towards company cars became more onerous, with increasing levels of taxation on the benefit-in-kind value of the ownership of a company car and on the provision of free fuel for private use. The paper sets out the changes in taxation policy affecting company cars in the UK, and looks at the associated reductions in company car ownership (including free fuel) and patterns of use. It goes on to look in more detail at which groups of the population have kept company cars and in which parts of the country they have been most used, and how these patterns have changed over time. A preliminary investigation is also made of possible substitution effects between company car and personal car driving and between company car use and rail travel. Clearly, the role of the company car is only one of many factors that are contributing to aggregate changes in levels of car use in Great Britain, alongside demographic changes and a wide range of policy initiatives. But, company car use cannot fall below zero, so the effect of declining year-on-year company car mileage suppressing overall car traffic levels cannot continue indefinitely.

Empirical Application of Expenditure Diary Instrument to Quantify Relationships Between In-Store and Online Grocery Shopping: Case Study of Greater London

There is a sustained shift of certain types of retail activity away from in-store shopping and toward online retailing, with potentially structural consequences for shopping-related mobility. In the United Kingdom, for instance, 5.1% of spending on groceries in 2013 was transacted online, an increase from 3.8% in 2010. (The level was 1.1% in 2003.) Transport researchers face serious gaps in empirical data coverage of this phenomenon, however, because regional and national travel surveys typically collect limited information with which to establish how in-store and online shopping relate to one another. To address this issue, the authors employed a well-established data resource in a novel approach. The UK Living Costs and Food Survey is traditionally used to track aggregate household expenditure patterns and to monitor price inflation. This study drew on the unique nature of the surveys expenditure diary, in which respondents recorded each item that they purchased during a 2-week period; respondents also recorded whether each shopping occasion was in-store or online. Empirically, it was found that shopping basket characteristics (types of products being purchased) were significantly linked with channel choice (online versus in-store). Furthermore, with a two-stage modeling approach, it was found that sociodemographic factors appeared to relate in different ways to adoption of online shopping in general and to the choice of online versus in-store for individual shopping occasions. The paper closes with a brief discussion of research needs to advance this line of inquiry.

Establishing the Links between Online Activity and Car Use: Evidence from a Combined Travel Diary and Online-Activity Pseudodiary Data Set

The links between online activity and physical mobility are of wide and growing interest to researchers, practitioners, and policy makers. This paper presents the results of an analysis of microdata from the Scottish household survey. The survey provides a unique, large-scale, nationally representative data set that includes both a travel diary instrument and a pseudodiary of participation in online activity. Multivariate regression models were estimated to relate peoples online-activity pro-files with their car driving mileage. The models included demographic and spatial characteristics to control for potential confounding effects. The analysis found that, net of other effects, compared with nonuse of the Internet, Internet usage was associated with a higher level of car use. The marginal effect of time spent online was, however, found to be negatively linked with car use. In other words, spending large amounts of time online is, all else equal, associated with less car driving mileage. The paper concludes with a discussion of further research needs to advance this line of inquiry.

Is Heightened Environmental Sensitivity Responsible for Drop in Young Adults' Rates of Driver's License Acquisition?

Across a range of developed societies, rates of drivers license acquisition by young adults have fallen from their historic peak levels (which in Britain were in the early 1990s). A widely discussed hypothesis to explain this trend is that the heightened environmental sensitivity of the current cohort of young adults could be fully or in part responsible. The objective of this study was to establish whether empirical evidence provided support for this hypothesis. Public opinion polling data from Britain and the United States and British National Travel Survey microdata were statistically analyzed. No evidence was found, either from the United States or Britain, of the populace becoming increasingly inclined toward environmental protection. On the basis of longitudinal trends in public opinion polling, the opposite seemed to be true. Analysis of British National Travel Survey data (n = 2,820 unlicensed adults aged 17 to 29) showed that few young British adults without drivers licenses (approximately 1%) reported that environmental sensitivity was either the main reason or a contributory reason that they had not acquired a drivers license. By contrast, more than half (59%) of not fully licensed young British adults reported that they were either learning to drive (27%) or were put off mainly by the license acquisition testing requirements (2%) or by costs associated with motoring (30%). These findings are evidence contrary to the hypothesis that growing environmental sensitivity is responsible for falling rates of licensing of young adults, at least in Britain and the United States.

Capacity Impacts and Optimal Geometry of Automated Cars’ Surface Parking Facilities

The impact of Automated Vehicles (AVs) on urban geography has been widely speculated, though there is little quantitative evidence in the literature to establish the magnitude of such effects. To quantify the impact of the greater precision of automated driving on the spatial efficiency of off-street parking facilities, we develop a mixed integer nonlinear model (solved via a branch-and-cut approach) and present comparisons against industry-standard requirements for human-driving operation. We demonstrate that gains on the order of 40–50% in spatial efficiency (parking spaces per unit area) are in principle achievable while ensuring that each parked vehicle is independently accessible. We further show that the large majority of these efficiency gains can be obtained under current automotive engineering practice in which only the front two wheels pivot. There is a need for standardized methods that take the parking supply of a city as an input and calculate both the aggregate (citywide) efficiency impacts of automated driving and the spatial distribution of the effects. This study is intended as an initial step towards this objective.

Reliability-Based Traffic Signal Control for Urban Arterial Roads

It is widely accepted that travelers value both the reliability of travel time and its mean or expected value. Strategies for traffic signal control typically seek to optimize average travel times, although reliability is in general not explicitly taken into account. In this paper, we propose a new framework for evaluating the consequences of signal-control tactics on both reliability and expected values of travel time, based on an analytic model of travel time distribution. A genetic-algorithm-based approach is then employed to identify optimal multicriteria signal control strategies, including sensitivity analysis, to the relative weighting between reliability and expected value. We expose the properties of the proposed framework via an empirical case study of four alternative optimization approaches (the signal setting optimized with the traditional Websters method, TRANSYT model, and the newly proposed model) under various traffic conditions. Results indicate that the newly proposed framework outperforms the alternative signal control strategies in terms of both travel-time variability and expected travel time.

Empirically Constrained Efficiency in a Strategic-Tactical Stated Choice Survey of the Usage Patterns of Emerging Carsharing Services

Abstract Purpose — The principal hypothesis of this program of research is that peoples choices of which resources to own are a function of expected travel needs. Methodology/approach — This chapter reports recent research using a stated-choice survey design that is innovative in two respects. First, respondents are asked to consider two types of choice having different time horizons but which are thought to be linked in a strategic-tactical structure. The two types of choices are (a) purchasing ‘mobility resources’, which include commitments such as car ownership and subscription to carsharing services and (b) choosing a mode of transport for a particular instance of travel. The second methodological innovation is that respondents indicate their choices in the context of giving advice to a demographically similar ‘avatar’. The development of a technique for ‘empirically constrained’ efficient design is discussed, as is its application to this survey. This objective is to provide survey designs with a high degree of statistical efficiency whilst maintaining plausibility in the combination of attribute levels. Field data from an empirical application (n = 72) was collected and analysed. Findings — The proposed method for efficient design proved successful. The main substantive findings from the empirical application are presented, along with detailed results relating to how different demographic classes of respondents engaged with the instrument. For instance, living with ones partner and living with no children at home were associated with high scores on a scale of similarity between the experimental choice context and ones real-world mobility choices. Research limitations/implications — The proposed techniques appear promising, though the empirical results must be viewed as indicative only due to the size and coverage of the field data sample.