Category Archives: modeling

Induced model complexity

When I was a naive young modeler, running the Travel and Travel/2 models for the Montgomery County Planning Departments, regional travel demand models took up to 24 hours to run in full form. Talking with modelers today, it seems models still take on the order of 24 hours to run. Why?

I posit “Induced Complexity.” When we build a road, we induce demand, travelers who were previously priced off the road due to congestion or extra travel time now switch times of day, routes, modes, and destinations to take advantage of the capacity, and new development is pursued. Similarly, when we get a bigger computer, we can either use it to run the same models faster, or to run more complicated models. It seems the profession leans to the latter. The complexity is in terms of the number of Transportation Analysis Zones, or in the number of Times of Day, or in the number of model components that are considered, or the degree of precision required in equilibrium.

This induced complexity is real, and like induced demand is not necessarily a bad thing (if the complexity improves accuracy, it is a good thing), but it is a thing we should all be cognizant of.

Journal of Transport and Land Use.

We are pleased to announce the Journal of Transport and Land Use.
What, you ask? Another journal amidst an already overcrowded field?
Yes, we respond enthusiastically! Several journals touch on the interaction of transport and land use; however, they do so peripherally. This new venue puts both transport and land use front and center. We seek to be the leading outlet for research at the interdisciplinary intersection of these two domains, including work from the domains of engineering, planning, modeling, behavior, economics, geography, regional science, sociology, architecture and design, network science, and complex systems.
The Journal of Transport and Land Use (JTLU) will be peer-reviewed, web-based, open-content, subscription-free, and free to contribute. All of this is enabled by support from the Center for Transportation Studies at the University of Minnesota, where the journal will be housed. The advantages of this new journal and new process are several:
1. With a rigorous peer-review process, only quality papers that meet scientific standards will be published within the journal.
2. By being web-based (and web-only), we reduce costs significantly compared with paper journals. Web-based publication allows a much faster turnaround time than paper publication. Our goal is six weeks between submission and first reviews returned to the author. Being web-based also allows the inclusion of full color graphics and multi-media content, and the inclusion of datasets with the publication.
3. By being open-content, papers published in JTLU can be freely distributed (with attribution), increasing the value of papers published in the journal, and increasing their likelihood of being used in course readers and being read by the public.
4. By being subscription-free, we overcome a fundamental problem of today’s expensive journals published by for-profit publishers, which many libraries can no longer subscribe to.
5. By being free-to-contribute, we overcome the burden of the open-content journals that charge the authors to publish their paper.
We are now soliciting papers covering topics at the intersection of transport and land use. Details about the journal, its editorial process, and paper submission can be found at the journal’s website http://www.jtlu.org .
If you are interested in organizing a special issue, please contact one of the editors.
There will be a meeting at the World Conference on Transport Research in Berkeley to discuss the journal, contact the editors for details.
We look forward to any comments, questions, or suggestions you may have.
Sincerely,
David Levinson and Kevin Krizek
David Levinson
Richard P. Braun/CTS Chair in Transportation Engineering
Director Networks, Economics, and Urban Systems (Nexus) Research Group
University of Minnesota (612) 625-6354
dlevinson@umn.edu

http://nexus.umn.edu

Kevin J. Krizek
Associate Professor, Urban Planning & Civil Engineering
University of Minnesota (612) 625 – 7318

http://www.kevinjkrizek.org