Category «Travel Modeling»

Shielding and Weaponizing Your Travel Model

Excerpt from “The Planners Guide to Advocacy Modeling” by Alan Horowitz Chapter 12.  Shielding and Weaponizing Your Travel Model  Earlier chapters of this book describe methods of building and calibrating a travel model to assure that it produces the desired policy outputs.  However, a model will not be particularly useful in advancing a political agenda unless certain steps are taken to …

How I Bought My House in Whitefish Bay (a Story About a Land-Use Model)

I must digress.  The first house Shirley and I bought was in the Detroit area.  After looking at several gorgeous, ridiculously cheap, mansions in the City of Detroit, we decided to look for more modest digs in the suburbs.  We wanted to identify the “good” neighborhoods near the GM Tech Center, so on a map I shaded 2-mile radius circles around every K-Mart.  The closest hole …

Six Short Essays on Highway Path Choice

Where are All the Trucks?  Getting Truck Costs Right Is Really Important  Several years ago, I was working with FAF (Freight Analysis Framework) truck assignment results for the upper Midwest.  Those early FAF assignments routed trucks according to travel time.  I noticed lots of trucks being assigned to the Chicago Skyway.  The Chicago Skyway is a short toll road that runs from the south side …

The Elusive Concept of Delay in Urban Traffic

I recently read a paper where the authors tried to compute a congestion index from ridesharing data for a city by comparing daytime average speeds to nighttime average speeds. While reading this paper I couldn’t help but to reflect on an experience I had while working at General Motors Research Laboratories decades ago. One GM …

Comments on “Forecasting the Impossible”

Norman Marshall’s article, “Forecasting the impossible: The status quo of estimating traffic flows with static traffic assignment and the future of dynamic traffic assignment,” slams conventional modeling practices.  Marshall states that MPOs routinely test alternatives that create unrealistically large flows on freeways and the consequential delays are so erroneous as to invalidate any impact analysis …

Statistical Testing is Essential to Transportation Research

I have lately refereed journal submissions where authors have totally evaded the concept of a statistical test while trying to demonstrate the importance of their research.  I will give somewhat altered (to protect the identities of the authors and avoid lawsuits) examples later.  Mainly, each of these authors has developed an innovation, compared the innovation …