Justice, Exclusion, and Equity: An Analysis of 48 U.S. Metropolitan Areas

Recent working paper

Injustice in transportation services experienced by disadvantaged demographic groups account for much of these groups’ social exclusion.

HoustonOppUnfortunately, there is little agreement in the field about what theoretical foundation should be the basis of measures of the justice of transportation services, limiting the ability of transportation professionals to remedy the issues. Accordingly, there is a need for an improved measure of the justice of the distribution of transportation services, which relates to the effectiveness of transportation services for all members of disadvantaged groups rather than for only segregated members of these disadvantaged groups. To this end potential measures of distributive justice, based on the accessibility to jobs provided by various modes, are evaluated in 48 of the top 50 largest metropolitan areas in the United States. The purpose of the study is to inform recommendations for appropriate use of each measure.

Sydney Transport/Urban Twitter/Blogosphere Meetup

Sydney Transport/Urban Twitter/Blogosphere Meetup – Friday Sept, 22 (6pm) at Hotel Sweeney’s 236 Clarence St, Sydney NSW 2000, Australia

Come one, come all.


Safety in Numbers and Safety in Congestion for Bicyclists and Motorists at Urban Intersections

Recent working paper:

The rate of number of crashes to traffic flow
The rate of number of crashes to traffic flow

This study assesses the estimated crashes per bicyclist and per vehicle as a function of bicyclist and vehicle traffic, and tests whether greater traffic reduces the per-car crash rate. We present a framework for comprehensive bicyclist risk assessment modeling, using estimated bicyclist flow per intersection, observed vehicle flow, and crash records. Using a two-part model of crashes, we reveal that both the annual average daily traffic and daily bicyclist traffic have a diminishing return to scale in crashes. This accentuates the positive role of safety in numbers. Increasing the number of vehicles and cyclists decelerates not only the probability of crashes, but the number of crashes as well. Measuring the elasticity of the variables, it is found that a 1% increase in the annual average daily motor vehicle traffic increases the probability of crashes by 0.14% and the number of crashes by 0.80%. However, a 1% increase in the average daily bicyclist traffic increases the probability of crashes by 0.09% and the number of crashes by 0.50%. The saturation point of the safety in numbers for bicyclists is notably less than for motor vehicles. Extracting the vertex point of the parabola functions examines that the number of crashes starts decreasing when daily vehicle and bicyclist traffic per intersection exceed 29,568 and 1,532, respectively.

Spatiotemporal Short-term Traffic Forecasting using the Network Weight Matrix and Systematic Detrending

Recent working paper:

LookBackWindowsThis study examines the dependency between traffic links using a three-dimensional data detrending algorithm to build a network weight matrix in a real-world example. The network weight matrix reveals how links are spatially dependent in a complex network and detects the competitive and complementary nature of traffic links. We model the traffic flow of 140 traffic links in a sub-network of the Minneapolis – St. Paul highway system for both rush hour and non-rush hour time intervals, and validate the extracted network weight matrix. The results of the modeling indi- cate: (1) the spatial weight matrix is unstable over time-of-day, while the network weight matrix is robust in all cases and (2) the performance of the network weight matrix in non-rush hour traffic regimes is significantly better than rush hour traffic regimes. The results of the validation show the network weight matrix outperforms the traditional way of capturing spatial dependency between traffic links. Averaging over all traffic links and time, this superiority is about 13.2% in rush hour and 15.3% in non-rush hour, when only the 1st -order neighboring links are embedded in modeling. Aside from the superiority in forecasting, a remarkable capability of the network weight matrix is its stability and robustness over time, which is not observed in spatial weight matrix. In addition, this study proposes a naïve two-step algorithm to search and identify the best look-back time win- dow for upstream links. We indicate the best look-back time window depends on the travel time between two study detectors, and it varies by time-of-day and traffic link.

Seminar: The End of Traffic and the Future of Access: A Roadmap for the New Transport Landscape


I am giving at talk at ITLS on Tuesday, September 19, 2017 at 14:00

Title: The End of Traffic and the Future of Access: A Roadmap for the New Transport Landscape

Venue : Abercrombie Building (H70) Level 5 – Room 5050 , Corner Abercrombie Street and Codrington Street, The University of Sydney

The University of Sydney: Click here for directions

RSVP is required if you wish to attend


Less than two decades into the new millennium, transport is becoming interesting again. Revolutionary technical advances are taking root; evolutionary social forces are responding; together, these phenomena are changing how people access and exchange goods. Transport and planning discussions are now being reshaped, prompting even seasoned transport professionals to appear as neophytes. This talk reframes the evolving nature of debates about transport and to shape perspectives about the future of transport in cities. It discusses the implications of automation, electrification, sharing, and demassification on travel demands and transport policy.


Prof. David Levinson teaches at the School of Civil Engineering at the University of Sydney, where he leads the Network Design Lab and the Transport Engineering group. He is an honorary affiliate of the Institute of Transport and Logistics Studies, where he is also a member of the Board of Advice. From 1999 to 2016, he served on the faculty of the University of Minnesota where he held the Richard P. Braun/CTS Chair in Transportation (2006-2016).  Levinson has authored or edited several books, including Spontaneous Access,  The Transportation Experience, and Planning for Place and Plexus, as well as numerous peer reviewed articles. He is the editor of the Journal of Transport and Land Use.

Traffic Flow Variation and Network Structure

Recent working paper

Figure4This study defines and detects competitive and complementary links in a complex network and constructs theories illustrating how the variation of traffic flow is interconnected with network structure. To test the hypotheses, we extract a grid-like sub-network containing 140 traffic links from the Minneapolis – St. Paul highway system. We reveal a real-world traffic network comprises both competitive and complementary links, and there is a negative network dependency between a competitive link pair and a positive network dependency between a complementary link pair. We validate a robust linear relationship between standard deviation of flow in a link and its number of competitive links, its link correlation with competitive links, and its network dependency with both competitive and complementary links. The results indicate the number of competitive links in a traffic network is negatively correlated with the variation of traffic flow in congested regimes as drivers are able to take alternative paths. The results also signify that the more the traffic flow of a link is correlated to the traffic flow of its competitive links, the more the flow variation is in the link. Considering the network dependency, however, it is corroborated that the more the network dependency between a link and its competitive links, the more the flow variation in the link. This is also true for complementary links.

Accessibility Oriented Development

Recent working paper:

AoDMunicipal governments worldwide have been pursuing transit-oriented development (TOD) strategies in order to increase transit ridership, curb traffic congestion, and rejuvenate urban neighborhoods. In many cities, however, development of planned sites around transit stations has been close to non-existent, due to, among other reasons, a lack of coordination between transit investments and land use at the regional scale. Furthermore, the ability to access transit differs from the ability to access destinations that people care about. Reframing transit-oriented development as accessibility-oriented development (AOD) can aid the process of creating functional connections between neighborhoods and the rest of the region, and maximize benefits from transport investments. AOD is a strategy that balances accessibility to employment and the labor force in order to foster an environment conducive to development. AOD areas are thus defined as having higher than average accessibility to employment opportunities and/or the labor force; such accessibility levels are expected to increase the quality of life of residents living in these areas by reducing their commute time and encouraging faster economic development. To quantify the benefits of AOD, accessibility to employment and the labor force are calculated in the Greater Toronto and Hamilton Area, Canada in 2001 and 2011. Cross-sectional and temporal regressions are then performed to predict average commute times and development occurring in AOD areas and across the region. Results show that AOD neighborhoods with high accessibility to jobs and low accessibility to the labor force have the lowest commute times in the region, while the relationship also holds for changes in average commute time between the studied time periods. In addition, both accessibility to jobs and accessibility to the labor force are associated with changes in development, as areas with high accessibility to jobs and the labor force attract more development. In order to realize the full benefits of planned transit investments, planning professionals and policy makers alike should therefore leverage accessibility as a tool to direct development in their cities, and concentrate on developing neighbourhoods with an AOD approach in mind.

The Healthiest vs. Greenest Path: Comparing the Effects of Internal and External Costs of Motor Vehicle Pollution on Route Choice 

On-road emissions, a dominant source of urban air pollution, damage human health. The ‘healthiest path’ and the ‘greenest path’ are proposed as alternative patterns of traffic route assignment to minimize the costs of pollution exposure and emission, respectively. As a proof-of-concept, the framework of a link-based emission cost analysis is built for both internal and external environmental costs and is applied to the road network in the Minneapolis – St. Paul Metropolitan Area based on the EPA MOVES and RLINE models. The healthiest and the greenest paths are skimmed for all work-trip origin-destination pairs and then aggregated into work trip flows to identify the healthier or greener roads in a comparative statics analysis. The estimates show that highways have higher emission concentrations due to higher traffic flow, on which, but that the internal and external emission costs are lower. The emission cost that commuters impose on others greatly exceeds that which they bear. In addition, the greenest path is largely consistent with the traditional shortest path which implies that highways tend to be both greener and shorter (in travel time) for commuters than surface streets. Use of the healthiest path would generate more detours, and higher travel times.
Route choice, Traffic assignment, Shortest path, Pollution, Emissions, Exposure, Intake

Warranties and Indemnities …

In this post I compare the digital conservancy/repository terms of service for two universities: Minnesota and Sydney.

The University of Minnesota Digital Conservancy I have used for a few years. It is well run and the staff are helpful.

The University of Minnesota:

There is one last step: In order for The UDC to reproduce, translate and distribute your submission worldwide, you must agree to the following terms. If you have questions regarding this agreement, please contact the Digital Conservancy staff: udc@umn.edu

By depositing this Content (“Content”) in the University Digital Conservancy (“Digital Conservancy”), I agree that I am solely responsible for any consequences of uploading this Content to the Digital Conservancy and making it publicly available, and I represent and warrant that:

I am either the sole creator and the owner of the copyrights and all other rights in the Content; or, without obtaining another’s permission, I have the right to deposit the Content in an archive such as the Digital Conservancy.

To the extent that any portions of the Content are not my own creation, they are used with the copyright holder’s express permission or as permitted by law. Additionally, the Content does not infringe the copyrights or other intellectual property rights of another, nor does the Content violate any laws or another’s rights of privacy or publicity.

The Content contains no restricted, private, confidential, or otherwise protected data or information that should not be publicly shared.

I understand that the Digital Conservancy will do its best to provide perpetual access to my Content. In order to support these efforts, I grant the Regents of the University of Minnesota (“University”), through its Digital Conservancy, the following non-exclusive, perpetual, royalty-free, world-wide rights and licenses:

to access, reproduce, distribute and publicly display the Content, in whole or in part, in order to secure, preserve and make it publicly available, and

to make derivative works based upon the Content in order to migrate the Content to other media or formats, or to preserve its public access.

These terms do not transfer ownership of the copyright(s) in the Content. These terms only grant to the University the limited license outlined above.

In contrast the University of Sydney eScholarship Repository is far less friendly in terms of licenses.

Sydney eScholarship Distribution License

There is one last step: In order for Sydney eScholarship to reproduce, translate and distribute your submission worldwide, your agreement to the following terms is necessary. Please take a moment to read the terms of this license, and click on one of the buttons at the bottom of the page. By clicking on the “Grant License” button, you indicate that you grant the following terms of the license.

Not granting the license will not delete your submission. Your item will remain in your “My Sydney eScholarship” page. You can then either remove the submission from the system, or agree to the license later once any queries you might have are resolved.

By this License, the Contributor, for the benefit of the University,
grants the University following rights.

1.	Definitions
Contributor means the author.contributor identified in the Sydney 
eScholarship Repository Metadata.

eScholarship Repository Metadata means the metadata encoded in the 
uploaded Works by the Contributor when accessing the Sydney 
eScholarship Repository.

University means The University of Sydney acting through Sydney 
eScholarship Repository, a body corporate under the University of 
Sydney Act 1989, ABN 15 211 513 464, of University of Sydney Library 
F03 University of Sydney, NSW 2006  Sydney  NSW  2006.

Work means the works listed [as Titles in the Sydney 
eScholarship Repository Metadata/in the Schedule to this License].

2.	Licence
The Contributor grants the University the non-exclusive perpetual 
license to reproduce and communicate the Work to the public via the 
Sydney eScholarship Repository and, without changing the content, to 
translate the Work to any medium or format for the purposes of 
preservation, research and study provided such use is not for a 
commercial purpose,  The Contributor also agrees that the University 
may keep more than one copy of the Work for the purposes of security, 
backup and preservation.

3.	Attribution
The eScholarship Repository will clearly identify the Contributor as 
the author of the Work.

4.	Acknowledgements
The Contributor acknowledges that:
(a)	they will not receive any payment from the University for the
 grant of rights under this License;
(b)	the Work is subject to the approval of the University and may
 not be accepted to the eScholarship Repository;
(c)	the University may remove the Work from the eScholarship 
Repository at any time at its absolute discretion; and
(d)	they have no termination rights under this License.

5.	Standard of work
In order for Work to be accepted to and remain on the eScholarship 
Repository, the Contributor acknowledges that:
(a)	the Work is academic and postgraduate (unless Work is an 
Honours Thesis or is otherwise approved by the University in writing)
; and
(b)	text material submitted is final draft or published version, 
and non-text material submitted is in its final form.

6.	Warranties
The Contributor warrants that:
(a)	the Work is their original work;
(b)	they have obtained consents in writing from all previous
publishers of the Work to enter into this License;
(c)	they have obtained consents in writing from third parties
which have any materials reproduced in the Work to publish the Work;
(d)	they can grant the rights under this License and the
University's exercise of those rights will not infringe the
copyright or other intellectual property rights of third parties;
(e)	to the best of their knowledge, the Work is accurate as at
the date in which the final version of the Work is submitted to the
University and as far as reasonably possible they have sought to
verify all statements in the Work which purport to be true and
(f)	to the best of their knowledge, the Work does not contain any
 scandalous, defamatory, or obscene material or any material which is
  actionable for interference with privacy, infringement of copyright,
  breach of confidence, passing off or contravention of any other
  private right; and
(g)	they have not engaged in any practices in preparing the Work
that would amount to plagiarism or any other form of academic
dishonesty or research misconduct under University policies and rules
 or which would (or would be likely to) bring the Contributor or the
 University into disrepute, and that they have complied with the
 University's policies, procedures and rules.
(h)	where the work is a thesis, it is a direct equivalent of the
final officially approved version that was submitted, and no
emendation of content has occurred other than minor variations in
formatting, that are the result of the conversion to digital format.

7.	Breach of warranty
The Contributor agrees to:
(a)	notify the University as soon as they become aware of any 
circumstances relating to the breach or potential breach of a 
warranty in clause 6;
(b)	allow the eScholarship Repository Coordinator to take any 
action to manage the University's exposure to such liability;
(c)	provide the University with all reasonable assistance in 
relation to the conduct or defence of any legal proceedings which may
 be commenced by or against the University in relation to the breach 
 of a warranty in clause 6; and
(d)	indemnify the University against any actions, costs or 
expenses arising out of the breach of a warranty in clause 6.

8.	Jurisdiction
The Contributor agrees that this License is governed by the law of 
New South Wales, submits to the non-exclusive jurisdiction of the 
courts in New South Wales and waives any right they have to object to
 an action being brought in those courts (including by claiming that 
 the action has been brought in an inconvenient forum or that those 
 courts do not have jurisdiction).
Note especially Clause 7.
“(d) indemnify the University against any actions, costs or expenses arising out of the breach of a warranty in clause 6.”
Why exactly would I agree to this? I assume it only applies if they lose (i.e. if a court rules a warranty has been breached), but even so, who really knows. As a general rule a university should be indemnifying its academic staff, not vice versa.
The University of Sydney libraries seem to have a much smaller repository.