Detours and induced demand

Bill Lindeke writes in MinnPost about Detours and induced demand Probably the craziest detour in Minnesota history was the impromptu rerouting following the Interstate 35W bridge collapse. Needless to say, the 2007 bridge tragedy was completely unexpected, and forced state agencies to reroute 150,000 cars per day into other parts of the Twin Cities’ freeway system. […]

Elements of Access: Induced Demand

PREDICTED TRAFFIC AND ACTUAL TRAFFIC AFTER A ROAD WIDENING by Wes Marshall You already have a congested roadway, and the transportation planners predict even more traffic on that road in the near future. What do you do? For most of the last century, the answer was to increase capacity. In the short-term, this seemed to […]

On “Induced Demand”

  JW Writes: A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King I strongly agree with David King’s recent post that we so often forget accumulated knowledge and that we seem to re-discover this knowledge in endless cycles. Nowhere does this seem more true than in the […]

Up or Out: Travel Demand and Thirty Minute Cities

Adapted from Levinson, D. and Krizek, K. (2017) The End of Traffic and the Future of Access. Network Design Lab. Cross-posted on the ITLS Thinking Outside the Box  blog. Each technological advance in mobility over the past 200 years increased the size of metropolitan areas. The ability to go faster, either owing to new technologies […]

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.” […]


How to value transport projects Instead of measuring and monetising the fairy dust of `travel time savings’, a transport facility should be assessed on how much access it produces per unit of investment. Access is the ease of reaching destinations. E.g. you might measure how many jobs (or restaurants or hospitals, etc.) can be reached in 30 minutes and/or $5 […]

Elements of Access — Now with Video

We are pleased to report that Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners by David M. Levinson, Wes Marshall, Kay Axhausen is now on YouTube. About the Book Nothing in cities makes sense except in the light of accessibility.  Transport cannot be understood without reference to the location of activities (land […]

On Hypo- and Hyper-connectivity in Transport

Connectivity is good. Is more connectivity better? During the early stages of a useful technology like roads or transit, adding links generally adds more benefits than costs. However there are limits. A four way intersection is good does not mean a five way intersection (or six or seven) is necessarily better. The more complex intersection […]