Paper published on retrospective routing with real-time GTFS data

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 on Dynamic Food Environments

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.

Photos from AAG 2017

A few photos of SAUSy Lab members from the 2017 AAG Annual Meeting below!

Misha Young, PhD Student – presenting his past work on transportation behaviours.
Dr. Michael Widener presenting his work on access to food and time use.
Tara Kamal-Ahmadi, PhD Student presenting her systematic review on using activity spaces in food environment research.

AAG 2017 Schedule

Check us out at the 2017 AAG! SAUSy affiliated presentations and abstracts in the links below:

Exploring the relationship between food shopping behaviour and transportation with time use data

A Systematic Review of Activity Spaces and Food-related Behaviours

Neighborhood context of aging-in-place: mapping the spatial patterns of aging in Canada

Transportation behaviours of single-person households in a Canadian context

Modelling the Effects of Space on Emergency Medical Transportation in Maryland, USA


Paper on urban cycling accepted!

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.


Hi there. Welcome to the SAUSy Lab at the University of Toronto. Not only are we a relatively new group, but we only just got a website. Lucky us! Lucky you!

One of the things about having a website, like writing a brochure or constructing your own home is that you have to put into tangible form a lot of messy, unresolved, still-evolving arrangements and ideals, not all of which everyone will agree on or has even tried to articulate before. For example, is this too casual a tone? Should it be dry and academic? Let’s try the first and see if anyone cares!

So what is the SAUSy lab? In general terms, if I must be stretched to provide an initial draft, the SAUSy Lab is a group of researchers, two professors and six graduate students, working on issues around transportation and quantitative method from a geographic or urban planning perspective. A couple subspecialties are cartography, health geography, and open-source GIS. As I say though, that is all still up in the air so if you don’t find that definition to be to your satisfaction, the best thing to do is either to give up because you didn’t care that much anyway, or to reach out to one of us and ask questions. If you’re considering applying to work with us, or if you already have, we do hope you’ll adopt the latter strategy!