Tijs Neutens

An Analysis of the Public Perception of Flood Risk on the Belgian Coast

In recent years, perception of flood risks has become an important topic to policy makers concerned with risk management and safety issues. Knowledge of the public risk perception is considered a crucial aspect in modern flood risk management as it steers the development of effective and efficient flood mitigation strategies. This study aimed at gaining insight into the perception of flood risks along the Belgian coast. Given the importance of the tourism industry on the Belgian coast, the survey considered both inhabitants and residential tourists. Based on actual experts risk assessments, a high and a low risk area were selected for the study. Risk perception was assessed on the basis of scaled items regarding storm surges and coastal flood risks. In addition, various personal and residence characteristics were measured. Using multiple regression analysis, risk perception was found to be primarily influenced by actual flood risk estimates, age, gender, and experience with previous flood hazards.

The Prism of Everyday Life: Towards a New Research Agenda for Time Geography

Abstract In light of the renewed attention for time geography in the transport modelling field in recent years, this paper provides a timely state‐of‐the‐art review of the contributions of the time‐geographic approach to the closely related research areas of transport planning and accessibility analysis. Specific attention will be devoted to the ways in which recent advances in time geography have deepened the understanding of human activities and travel possibilities in space and time. From this literature review, a detailed research agenda is derived and the latest research attempts to deal with lingering time‐geographic issues are discussed.

Space-time opportunities for multiple agents: a constraint-based approach

Constraint‐based models and models constructing accessibility measures mainly focus on single agents having only one available transport mode. However, numerous cases exist where multiple agents or groups of individuals with different available transport modes want to participate in a joint activity at a certain location. The aim of this paper is to provide new insights into representing and reasoning about feasible space–time opportunities for multiple agents. Relying on concepts of time geography, we propose a conceptual framework in order to determine interaction spaces for groups of individuals. Besides availability of means of transport and the locations of each individual, minimum activity duration and opening hours of opportunities are taken into account. The reasoning about space and time is visualized in three dimensions using a hybrid (CAD/GIS) system.

A three-dimensional network-based space–time prism

Time-geographic concepts are effective tools for the geovisualization of human activity patterns and to assess individual accessibility. In their traditional form, however, time-geographic concepts assume uniform travel velocities in an isotropic and homogeneous space. Because transportation systems confine travellers to links of road and rail networks with time-varying flows, these premises are typically unsatisfied in real-world situations. This paper provides an innovative approach to ameliorate the realism and applicability of space–time prisms by developing new three-dimensional space–time objects. Three-dimensional solid models which account for non-uniform movement are discussed, and their usefulness is assessed and illustrated by means of an example.

My space or your space? Towards a measure of joint accessibility

Abstract Research on space–time accessibility is usually concerned with determining and assessing the opportunities for individual activity participation. However, a significant part of everyday activities is conducted jointly with others, implying that the feasibility of potential locations for activity engagement depends on the accumulation of conditions related to the spatiotemporal setting of each participant. In this paper, we put forward a method to gauge the accessibility of places to a particular group of people willing to engage in a joint activity. The method calculates locational benefits by taking into account network-based travel times, individual activity schedules, and the attractiveness and temporal availability of facilities. The applicability of the method extends towards situations with multiple facilities and participants, being available for multiple periods of time. As a possible output of our model, maps of joint accessibility are created which can be used to evaluate different rendezvous scenarios.

Equity of urban service delivery: a comparison of different accessibility measures

This paper evaluates the use of various place-based and people-based measures of accessibility in the context of public service delivery. While place-based measures examine the spatial separation between service locations and in a single reference location, people-based measures are based on detailed observations of an individuals activity schedule and space–time constraints. The aim of this paper is to contribute to previous methodological studies of accessibility by investigating the extent to which utility-based measures relying on the Burns–Miller framework relate to place- based and other people-based measures of individual accessibility. In total, four place-based and six people-based measures that are frequently used to evaluate urban service delivery are analyzed. The relationships between these measures are examined and their implications for the assessment of equity of urban service distribution are evaluated. We have found substantial differences between place-based and people-based measures, supporting previous findings in the relevant literature and extending them to utility-based space–time measures of accessibility. We also observed substantial differences within the group of people-based measures. It appears that measures which express the cardinality of a feasible opportunity choice set are quite different from measures which express the desirability of such a set. The salience of this difference is also borne out by the measurement of statistical dispersion of accessibility values, indicating that different measures provide markedly different insights into how equally service delivery is distributed among the population.

The Social Interaction Potential of Metropolitan Regions: A Time-Geographic Measurement Approach Using Joint Accessibility

We put forward a method for measuring the social interaction potential of a metropolitan region based on the time-geographic concept of joint accessibility. The metric is sensitive to prevailing land use patterns and commuter flows in the metropolitan region, time budgets, and the spatial distribution of joint activity locations. It is calculated via a geocomputation routine in which a representative subset of after-work, space–time prisms are intersected with each other. Decomposition of the metric gives rise to social potential metrics for each employment and residential zone in the city, for specific commuter flows, and for locations of potential social interaction, such as bars, restaurants, sports fields, and so on. The method is demonstrated via a scenario-based experiment that explores the impact of residential and employment land use patterns and varying levels of commuter flow dispersion. The findings indicate that the metric is adequately responsive to each of the scenario input parameters, as well as pairwise combinations of parameters. Following the experiment, an empirical example using flow data from Salt Lake City, Utah, is presented. Insights on how to introduce more realism in the calculation of the metric for actual metropolitan regions for comparative purposes are then put forward. Finally, the article concludes with a discussion of the broader applications of this metric to various topical areas in urban geography including segregation, social capital development, innovation and creativity, and location allocation of facilities and their opening hours.

Using urban commuting data to calculate a spatiotemporal accessibility measure for food environment studies

Improving spatial access to healthy foods in urban regions is recognized as an important component of reducing the prevalence of chronic illness and achieving better health outcomes. Previously, researchers exploring this domain have calculated accessibility measures derived from the travel cost from home locations to nearby food stores. This approach disregards additional opportunities that present themselves as residents move throughout the city. A time-geographic accessibility measure is utilized to explore how single-occupancy automobile commuting affords access to supermarkets. Results show residents in some TAZs have more access when accounting for their commuting behavior than when measuring access from their home. This finding suggests more nuanced calculations of accessibility are necessary to fully understand which urban populations have greater access to healthy food.

Anchor uncertainty and space-time prisms on road networks

Space-time prisms capture all possible locations of a moving person or object between two known locations and times given the maximum travel velocities in the environment. These known locations or ‘anchor points’ can represent observed locations or mandatory locations because of scheduling constraints. The classic space-time prism as well as more recent analytical and computational versions in planar space and networks assume that these anchor points are perfectly known or fixed. In reality, observations of anchor points can have error, or the scheduling constraints may have some degree of pliability. This article generalizes the concept of anchor points to anchor regions: these are bounded, possibly disconnected, subsets of space-time containing all possible locations for the anchor points, with each location labelled with an anchor probability. We develop two algorithms for calculating network-based space-time prisms based on these probabilistic anchor regions. The first algorithm calculates the envelope of all space-time prisms having an anchor point within a particular anchor region. The second algorithm calculates, for any space-time point, the probability that a space-time prism with given anchor regions contains that particular point. Both algorithms are implemented in Mathematica to visualize travel possibilities in case the anchor points of a space-time prism are uncertain. We also discuss the complexity of the procedures, their use in analysing uncertainty or flexibility in network-based prisms and future research directions.

A commuter-based two-step floating catchment area method for measuring spatial accessibility of daycare centers

This paper puts forward a commuter-based version of the two-step floating catchment area (2SFCA) method, which has gained acceptance in studies on spatial health care accessibility. Current implementations of the 2SFCA method are static in that they consider centroid-based night-time representations of the population. The proposed enhancement to the 2SFCA approach addresses this limitation by accounting for trip-chaining behavior. The presented method is illustrated in a case study of accessibility of daycare centers in the province East Flanders in Belgium. The results show significant spatial differences in accessibility between the original and commuter-based version of the 2SFCA (CB2SFCA). They highlight the importance of giving heed to more complex travel behavior in cases where the need for detailed accessibility calculations is apparent.