Based on three decades of personal experience this paper provides suggestions for researchers who consider to have contacts with policy makers, politicians, and the media (PPM actors). The point of departure is that such contacts may be beneficial for researchers and their institutes, as well as for policy making and wider society. The core of the paper is a set of ten recommendations. These recommendations focus on having contacts with PPM actors at all, and if so: under which conditions, discussing the questions to be answered, the importance of core messages, scientific underpinnings of answers, the storyline of answers, the different mindsets of researchers as opposed to PPM actors, avoiding criticizing politicians, the benefits for researchers of having contacts with PPM actors, and proactively contacting PPM actors.

This study explores perceived accessibility specific to air transportation in the Dutch context through a focus group study. Five focus group sessions were held with a total of 24 participants with air travel experience within the past five years. Online focus groups were held during the period that the COVID-19 pandemic travel restrictions were in effect, specifically around 12 months after the travel restrictions were implemented globally. In terms of the importance of activities accessible by flight, we observe that travelers particularly attach importance to visiting family and relatives, while the importance attached to the business and recreational activities accessible by flight varies among participants. As far as the transport component of accessibility is concerned, we find that, in addition to conventional variables in air transportation research, such as cost and travel times, unconventional variables such as uncertainty during flight schedule disruptions or the mood of staff and other passengers contribute to perceived accessibility by air transportation. Based on the results, we further discuss characteristics specific to perceived accessibility by air transportation, directions for further qualitative and quantitative research regarding perceived accessibility by air transportation, and implications for policy and planning.

This research investigates the influence of socio-cultural factors and sociodemographic characteristics on bicycle use in Auckland, a multi-cultural city in New Zealand. To identify the strength of socio-cultural factors compared to other various social psychological determinants, a conceptual model is proposed encompassing Socio-cultural influences, Price Value, Perceived Safety and Security, Perceived accessibility, Information and Engagement, and Bicycle use. Using Structural Equation Modelling (SEM), the effects of these determinants on bicycle use were assessed. The moderating effects of sociodemographic factors including age, gender, ethnicity, and income level on the influence of these determinants on bicycle usage were also examined. Results suggest that socio-cultural influences have the strongest impact on bicycle use in Auckland, showing that those who ride a bicycle more than others are influenced more by family, friends, community, and culture to use a bicycle. Additionally, sociodemographic characteristics only moderate the influence of socio-cultural factors on bicycle usage indicating that socio-cultural factors influence bicycle use differently across various population groups. The strong influence of socio-cultural factors and the moderating role of sociodemographic characteristics on bicycle use in Auckland suggest that social and cultural dynamics are critical in shaping individual decisions to cycle, even more than practical considerations such as price, infrastructure, engagement, or safety. Therefore, transport strategies targeting specific population groups and relevant socio-cultural barriers can enhance bicycle use and promote equity in cycling. Suggested transport strategies include integrating socio-cultural initiatives with local government's transport policies such as education, community engagement, and awareness campaigns, implementing effective monitoring and evaluation initiatives followed by longitudinal investigations, and incorporating cultural representation in cycling initiatives. These short-term, mid-term, and long-term strategies can guide the development of more inclusive and effective transport strategies to enhance cycling participation across diverse demographic groups and achieve broader societal benefits.

Van februari 2003 tot januari 2025 werkte ik aan de TU Delft als hoogleraar Transportbeleid. Wat zijn belangrijke trends in ontwikkelingen, in onderzoek en beleid? Dit artikel geeft een beknopt en selectief overzicht van enkele dominante onderwerpen, met het accent op personenvervoer.

This chapter provides a systematic framework for assessing equity in urban accessibility, highlighting its growing importance to policymakers and researchers. It first clarifies the concept of accessibility—how land use, transport, temporal factors, and individual characteristics collectively shape people's ability to reach desired destinations—and links this to fairness. The chapter then explores dominant ethical principles underpinning equity evaluations, focusing on egalitarianism (minimizing accessibility differences between groups) and sufficientarianism (ensuring everyone meets a basic threshold level). Next, it examines commonly used quantitative indicators—such as the Gini index and the coefficient of variation—to measure and compare equity levels in accessibility outcomes. It also underscores the significance of spatial aggregation, showing that the chosen scale (e.g., individual addresses, neighborhoods, municipalities) can greatly influence perceived inequalities. These findings stress the need for careful methodological decisions when analyzing distributions of accessibility across diverse populations and areas. Finally, the chapter concludes that the literature and methods for evaluating equity of accessibility remain evolving. Future research could incorporate different ethical frameworks, more detailed considerations of individual preferences and perceptions, additional destination types, and the role of digital access. Collectively, this guidance supports well-informed, context-sensitive policy decisions to foster more equitable urban mobility.

A biased preference for the status quo could explain the increased support for policies following their implementation. However, the influence of status quo bias on support for transport policies has been analysed to a limited extent only. The counterfactual test serves as a potential method to empirically explore this influence by framing policies as the existing or alternative situation. This paper employs the counterfactual test to ascertain whether individuals disproportionately favour the status quo. To this end, we have designed separate experiments focusing on three transport policies: road pricing, speed limits, and train ticket fare differentiation. The results indicate that status quo bias does indeed influence support for transport policies. Participants prefer each policy option when framed as the status quo. In contrast, support for the same policy option declines when presented as the alternative situation. These findings underscore the irrational tendency to adhere to the status quo, which may stem from psychological commitments or cognitive misperceptions. Therefore, politicians, policymakers, and practitioners should anticipate a bias towards the status quo when introducing controversial transport policies.

In this paper we propose a meta-theory for travel and travel-related choices (MTTC). The meta-theory envisions that travel choices are based on five building blocks: (1) travel motivations (regarding whether to travel or not in the first place, and regarding the choice of specific alternatives associated with the main decision to travel), (2) the decision-making paradigm, (3) the type of travel choice, (4) personal characteristics, and (5) context factors. After explaining each of these building blocks, the paper offers a conceptual model that links them. It closes with some suggested avenues for future research. The MTTC helps researchers to explicitly underpin their methodological choices. In addition, we conclude that there is much heterogeneity with respect to the combinations of the five building blocks of the MTTC, and allowing for this heterogeneity improves our understanding of travel (-related) choices.

The aim of this conceptual paper is to contribute to a better understanding of the front-end phase of large public projects, which is complex and non-linear. The point of departure relates to a number of paradoxes found along the way of the front-end. A processual approach is taken to follow the front-end over time. Considering a number of example vignettes, four paradoxes and subsequent trade-offs are discussed which affect the strategic decisions that need to be made. These are found to fit largely within four generic sub-processes identified in the front-end. Inspired from the paradox theory, we conceptualise paradoxes and trade-offs under the dynamic equilibrium model adapted for temporary organising such as large public projects. Main aim of this paper is to consider how decision-making can be improved, and managerial strategies developed that permit the acceptance of paradoxes and their resolution in a virtuous cycle leading to long term success.

Air transportation is a mode of transport developed specifically to provide access to long-distance destinations that may otherwise be infeasible or at least more difficult to reach. Accordingly, there are distinct aspects of air travel that require consideration when assessing accessibility by air transportation, which are not addressed in general local accessibility studies. This paper reviews studies of accessibility by air transportation. The studies in question were published in academic journals, and we analysed them using the broad theoretical framework of accessibility of Geurs and van Wee [Accessibility evaluation of land-use and transport strategies: Review and research directions. Journal of Transport Geography, 12(2), 127–140]. We discuss the characteristics of accessibility by air transportation to consider when designing research, as well as trends and knowledge gaps in the existing literature. An important gap is that, while there is a growing interest towards perceived accessibility by air transportation, accessibility measures based on this perspective have not yet been applied yet. Additionally, the literature is largely focused on the transport and land-use components of accessibility as opposed to the individual and temporal components. We finish by discussing the benefits and drawbacks of directly applying conventional accessibility measures for research on accessibility by air transportation, as well as options to modify the temporal component of conventional person-based accessibility measures for better applicability in the air travel context.

This study aims to evaluate equity in cycling initiatives and their operational challenges by reviewing a wide range of cycling initiatives implemented in Auckland, New Zealand. The effectiveness of current initiatives with respect to various target groups or resulting beneficiaries is discussed, along with potential additional initiatives, barriers to implementing cycling equity initiatives in practice, and possible solutions to address such barriers. By interviewing policymakers, decision-makers, planners, designers, and transportation professionals, 44 cycling initiatives are identified. Results suggest that the geographical distribution of some of the current initiatives implemented could be more equitable. While some initiatives are equitable, there remain challenges with respect to their implementation. Additionally, there are limited initiatives focusing on the safety of female cyclists in Auckland, and no initiatives specifically aimed at Māori and Pacific people, groups that can both be considered disadvantaged with respect to cycling in Auckland. Potential additional policy initiatives include e-bike/bicycle subsidies, policy and law changes, education and awareness campaigns, better urban planning, policies aimed at making cycling easier, and better monitoring and evaluation. Barriers to the implementation of cycling equity initiatives in practice include sociocultural issues, financial constraints, poor planning, human resource limitations, and the built environment. Suggested strategies to help overcome some of these issues include adopting an equity lens and providing equity assessments for all initiatives, thus providing a wider coverage with respect to diversity in the population, enhanced engagement with the community, and the empowerment of people.

A biased preference for the status quo could explain the increased support for policies following their implementation. However, the influence of status quo bias on support for transport policies has been analysed to a limited extent only. The counterfactual test serves as a potential method to empirically explore this influence by framing policies as the existing or alternative situation. This paper employs the counterfactual test to ascertain whether individuals disproportionately favour the status quo. To this end, we have designed separate experiments focusing on three transport policies: road pricing, speed limits, and train ticket fare differentiation. The results indicate that status quo bias does indeed influence support for transport policies. Participants prefer each policy option when framed as the status quo. In contrast, support for the same policy option declines when presented as the alternative situation. These findings underscore the irrational tendency to adhere to the status quo, which may stem from psychological commitments or cognitive misperceptions. Therefore, politicians, policymakers, and practitioners should anticipate a bias towards the status quo when introducing controversial transport policies.

Car sharing contributes to reducing emissions, resource depletion, and land take, by promoting more efficient use of vehicles that on average sit idle 96% of the time. But consumer adoption remains limited. User segmentation studies can inform efforts to mobilize potential users to join car sharing, and to anticipate what their needs and usage characteristics will be. This paper proposes a comprehensive segmentation method based on socio-demographic variables, which reveals differences in preferences for car sharing platform type, usage characteristics and societal outcomes of car sharing use. To do so, we apply a three step Latent Cluster Analysis to a nationwide sample of active car sharing users. This method results in a set of user segments that reflect distinct life phases, with different needs in terms of the frequency and type of trips made by car sharing. This is reflected in different preferences for car sharing platform types, as the likelihood to use peer-to-peer car sharing as opposed to business-to-consumer car sharing differs by user segment. The segments do not differ substantially in their motivations for engaging with car sharing. Yet, environmental motivations for car sharing outrank financial motivations, while social motivations play no substantial role. The clusters do show substantial differences in the changes in car ownership that occur while being an active car sharing member as well as the likelihood to use car sharing in place of a private car rather than public transport or walking and biking. We conclude that a comprehensive segmentation method based on socio-demographic variables provides actionable insights for upscaling car sharing adoption, as well as targeting specific user segments in order to optimize societal outcomes from car sharing use.

Smooth cycling can improve the competitiveness of bicycles. Understanding cycling speed variation during a trip reveals the infrastructure or situations which promote or prevent smooth cycling. However, research on this topic is still limited. This study analyses speed variation based on data collected in the Netherlands, using GPS-based devices, continuously recording geographical positions and thus the variation in speeds during trips. Linking GPS data to spatial data sources adds features that vary during the trip. Multilevel mixed-effects models were estimated to test the influence of factors at cyclist, trip and tracking point levels. Results show that individuals who prefer a high speed have a higher average personal speed. Longer trips and trips made by conventional electric bicycles and sport bicycles have a higher average trip speed. Tracking point level variables explain intra-trip cycling speed variations. Light-medium precipitation and tailwind increase cycling speed, while both uphill and downhill cycling is relatively slow. Cycling in natural and industrial areas is relatively fast. Intersections, turns and their adjacent roads decrease cycling speed. The higher the speed, the stronger the influence of infrastructure on speed. Separate bicycle infrastructure, such as bike tracks, streets and lanes, increase speed. These findings are useful in the areas of cycling safety, mode choice models and bicycle accessibility analysis. Furthermore, these findings provide additional evidence for smooth cycling infrastructure construction.

As cities grow, the benefits of living in them are increasingly unequally distributed. USA cities, in particular, have experienced rapid suburbanization of poverty and decreased levels of access to jobs for transit-dependent and vulnerable communities. The public transit challenges in suburbs call for innovative forms of transit to turn the tide on urban inequality. On-demand microtransit, a novel type of shared mobility provides efficient, convenient and affordable transportation. Its potential for redressing inequity had yet to be investigated fully in a suburban setting. We presented a case study from the suburbs of Minneapolis-St. Paul in Minnesota, USA. We combined unique datasets of microtransit ridership from two public transit agencies, transit surveys, land use data, and expert interviews, to conduct spatial analysis, accessibility analysis, and equity impact assessments for these suburbs. We found that microtransit enables public transit agencies to reach a larger number of vulnerable riders than fixed-route transit, particularly for commuting and trips to/from commercial areas. Microtransit also provided a cheaper alternative to ride-hailing and a faster alternative to public transit and walking, without cannibalizing ridership from fixed-rout transit alternatives. Finally, microtransit redressed transportation inequities by alleviating access inequality, reaching vulnerable rider groups effectively, and creating travel opportunities that are less spatially concentrated than those provided by traditional, fixed-route public transit. This study provided a framework for further investigations into the impact of microtransit, including in urban core or rural settings, and highlighted the impact of microtransit in reducing access inequity in a suburban environment.

Latent Class Analysis was used on the 2018/19 Dutch National Travel dataset to assess travel behaviour profiles and its connection with sociodemographic and spatial factors to grasp travel patterns in a more holistic context than previous research

Car dependence brings along many negative social and environmental externalities that policymakers and stakeholders need to consider. Nonetheless, the concept is not well defined and lacks a clear framework regarding its determinants and mechanisms, which also leads to problems in terms of its operationalisation. Therefore, this paper proposes a conceptualisation and operationalisation of car dependence, which can serve as a basis for further research and policy. We define car dependence as the extent to which an individual is incapable to participate in location-based activities without a car in a satisfactory way. This definition is based on the theoretical background of the capabilities approach and the concept of motility and also linked to the concept of accessibility. Our conceptual model consists of seven components, most of which have been considered separately in previous conceptualisations, namely the land use system, transport system, natural environment, temporal component, social environment, and individual objective/subjective characteristics. These components range from being external to the individual (e.g. the land use system) to internal (e.g. individual features). Considering these components jointly emphasises the importance of looking at car dependence in a holistic, unifying way. This approach contributes to a better understanding of car dependence that goes beyond the explicit analysis of components in previous research. In addition, we provide a systematic approach to operationalising car dependence that contributes to a more comparable approach to measuring car dependence. Researchers have to decide whether they want to examine car dependence via its components or via self-report by individuals, whether they want to study the full set of components or only a subset, and whether they want to consider perceptions or factual information about external components. Therefore, our conceptualisation and operationalisation provide valuable new insights into car dependence regarding new research directions and policy approaches.

In this paper we assume that people could travel in some cases to escape from something, such as their family, colleagues, or residential or work area. The concept of escaping as a driver to travel complements both the mainstream assumption that travel is a derived demand and the idea that people sometimes travel for the fun of it (and thus derive a positive utility from travelling), and has its origin in sociological literature. We categorize forms of escaping, and link travel to escape (TtE) to other concepts such as travel time budgets. Next we propose a first conceptual model relating factors explaining the motivation for escaping from something, or being able to escape from something, and the subsequent travel behaviour. We then formalize the travel behaviour model with general functions incorporating the role of travel to escape. Next we present the results of a first, small, empirical study showing that some people recognize the concept of escaping. In addition, we discuss the implications of travel motivated by escaping from something, one implication being that there will be more travel than if the concept does not apply, and another implication being the potentially positive value of a low level of accessibility, rather than the high level customarily assumed to be more desirable. We finally discuss implications for future research, and end with a discussion and final conclusion.

This extensively updated textbook introduces the transport system and its societal impacts in a holistic and multidisciplinary way. A timely second edition, it includes new analyses of travel behaviour and the transport system’s impacts on health and well-being.

Innovations in transportation can contribute to reaching relevant societal objectives (e.g. reduce emissions, congestion levels and/or risks). To determine which innovations to stimulate (and which not) it is important for policy makers to assess their effects on beforehand. Expert judgement is an often-used method for this purpose. Although expert opinions can provide useful input for decision-making, these judgement are potentially subject to change, for example, due to new information becoming available or because the (academic) discussion about the innovation in question takes a new turn. Studies that explicitly study stability and change in expert judgements are rare, but highly relevant to determine the reliability of experts' assessments. To address this gap, this study assesses experts’ judgments at multiple points in time focusing on the effects of a transport innovation with potentially widespread societal implications, namely Automated Vehicles (AVs). To this end a survey was administrated to a group of experts involved in the WISE-ACT project. The results indicate that expert opinions towards this innovation are generally favorable; AVs are believed to reduce congestion delays, greenhouse gas emissions and traffic accidents. Although the consulted experts are generally quite stable in their opinions, they are becoming less optimistic about these positive effects over time. A Q-factor analysis additionally reveals two clusters of experts, one with a positive and one a negative outlook on AVs. The latter group beliefs that AVs will lower the value of travel time, thereby increasing travel demand, and, in turn, emission and congestion levels. Overall, the changing and diverging opinions among experts indicate that the transition to AVs is not necessarily regarded as a desirable one.