The following paper has recently been accepted for publication by the Journal of Transport Geography:
Constructing a Routable Retrospective Transit Timetable from a Real-time Vehicle Location Feed and GTFS
Nate Wessel, Jeff Allen & Steven Farber
We describe a method for retroactively improving the accuracy of a General Transit Feed Specification (GTFS) package by using a real-time vehicle location dataset provided by the transit agency. Once modified, the GTFS package contains the observed rather than the scheduled transit operations and can be used in research assessing network performance, reliability and accessibility. We offer a case study using data from the Toronto Transit Commission and find that substantial aggregate accessibility differences exist between scheduled and observed services. This ‘error’ in the scheduled GTFS data may have implications for many types of measurements commonly derived from GTFS data.
Preproof of the paper
New paper published in Applied Geography by SAUSy Lab members Widener, Farber, and Allen (and others):
How do changes in the daily food and transportation environments affect grocery store accessibility?
A healthy food environment is an important component in helping people access and maintain healthy diets, which may reduce the prevalence of chronic disease. With few exceptions, studies on healthy food access in urban regions typically ignore how time of day impacts access to food. Similarly, most extant research ignores the complexities of accounting for the role of transportation in spatial access. Examining healthy food access is important, especially for populations whose day-to-day schedules do not align with a typical work schedule. This study profiles novel methods that can be used to examine the daily dynamics of food access in Toronto, Ontario, using grocery stores as a case study to examine the changing geographies of food access over a 24-h period, and the impact of a changing public transit schedule on food access. Walking and automobile travel times are also reported. Results indicate that access to grocery stores is severely diminished for large parts of the city in the late night and early morning, and that public transit travel times are higher and more variable in the early morning hours. Ultimately, this research demonstrates the need for further study on how residents with nonconventional schedules experience, and are affected by, the dynamic food and transportation environments. Future research should build upon the methods presented here to include a broader range of food retailers.
Dwelling Type Matters: Untangling the Paradox of Dwelling Type and Mode Choice
(By Trudy Ledsham, Steven Farber, and Nate Wessel) has just been accepted to the Transportation Research Record!
Urban intensification is believed to result in modal shift away from automobiles to more active forms of transportation. This work extends our understanding of bicycle mode choice and the influence of built form, through analysis of dwelling type, density and mode choice. Both apartment dwelling and active transportation are related to intensification, but our understanding of the impact of increased density on bicycling is muddied by lack of isolation of cycling from walking in many studies, and lack of controls for the confounding effects of dwelling type. This paper examines the relationship between dwelling type and mode choice in Toronto. Controlling for 25 variables, this study of 223,232 trips used multinomial logistic regression analysis to estimate relative risk ratios. Compared to driving, we found strong evidence that a trip originating from an apartment-based household was less than half as likely to be taken by bicycle as a similar trip originating in a house-based household in Toronto in 2011. Increased population density of the household location had a positive impact on the likelihood of a trip being taken by walking and a negligible and uncertain impact on the likelihood of it being taken by transit, but a
negative impact on bicycling. Further analysis found the negative impact of density does not seem to apply to those living in single detached housing, but rather it only negatively impacts the likeliness of cycling among apartment and townhouse dwellers. Further research is required to identify the exact barriers to cycling, apartment dwellers experience.
Unfortunately, we cannot provide a direct link to the paper at this time, but we’ll provide a link to TRR once the paper is published.