Transportation demand models offer predictions that are used to make important decisions, but their accuracy is questionable. The real issue, however, might be about the goals of planning and how urban life and livability are quantified.

"Despite them being a legally required portion of any transportation infrastructure project that gets federal dollars, it is one of urban planning’s worst kept secrets that [travel demand] models are error-prone at best and fundamentally flawed at worst," writes Aaron Gordon.
Gordon says the primary issue is not so much whether these models could produce better results but rather why they are considered the best guides to make planning and policy decisions. "TDMs, its critics say, are emblematic of an antiquated planning process that optimizes for traffic flow and promotes highway construction. It’s well past time, they argue, to think differently about what we’re building for," says Gordon.
Gordon describes major issues with TDMs: assumptions about population, land-use patterns, and travel decision-making as fixed and predictable. The flip side, he says, is induced demand, where expanded roadway capacity does not relieve congestion but rather amplifies it. "To fully appreciate the absurdity of this quest, look no further than the $2.8 billion freeway project in Katy, Texas that was supposed to reduce commute times along the expanded 23-lane freeway, the widest in the world. All too predictably, congestion only increased, and commute times are longer still."
TDM critics say the focus should be on different measures that reflect quality-of-life issues such as access to public transit, parks, and walkable neighborhoods. “The question is not whether the predictions of how they will behave are accurate, but what kind of behavior we want to have more of,” adds Gordon.
FULL STORY: The Broken Algorithm That Poisoned American Transportation

San Diego to Rescind Multi-Unit ADU Rule
The city wants to close a loophole that allowed developers to build apartment buildings on single-family lots as ADUs.

Has President Trump Met His Match?
Doug Ford, the no-nonsense premier of Canada's most populous province, Ontario, is taking on Trump where it hurts — making American energy more expensive.

Study: London ULEZ Rapidly Cleaning up Air Pollution
Expanding the city’s ultra low-emission zone has resulted in dramatic drops in particle emissions in inner and outer London.

San Jose Mayor Takes Dual Approach to Unsheltered Homeless Population
In a commentary published in The Mercury News, Mayor Matt Mahan describes a shelter and law enforcement approach to ending targeted homeless encampments within Northern California's largest city.

Atlanta Changes Beltline Rail Plan
City officials say they are committed to building rail connections, but are nixing a prior plan to extend the streetcar network.

Are Black Mayors Being Pushed Out of Office?
The mayors of New York, St. Louis, and Pittsburgh all stand to lose their seats in the coming weeks. They also all happen to be Black.
Urban Design for Planners 1: Software Tools
This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.
Planning for Universal Design
Learn the tools for implementing Universal Design in planning regulations.
Resource Assistance for Rural Environments
City of Edmonds
City of Grandview
Harvard GSD Executive Education
UCLA Lewis Center for Regional Policy Studies
City of Piedmont, CA
Great Falls Development Authority, Inc.
HUDs Office of Policy Development and Research