Cracking the upward GHG emissions curve in the transport sector has proved exceedingly difficult. Research from Aalborg University in Denmark suggests that in some industrialized societies this may be changing.
According to the International Energy Agency greenhouse gas emissions (GHG) from the transport sector have continued to rise in both the industrialized and industrializing countries, and are projected to continue to do so well into the 2030s and 2040s. One of the explanations for this is the strong network effects (path dependencies) associated with the system of car-based travel, where capacity expansions of the highway network induce further demand for higher automotive mobility.
Recent research from Aalborg University in Denmark suggests that, at least in the case of the Copenhagen and Portland, Oregon metropolitan areas, the existing system of dependence on high-carbon modes of transport may be weakening. Changes in demography, fuel prices, behavior, residential location preference, and environmental concerns are all contributing to a reduction in vehicle miles traveled (VMT) across North America and Europe, thereby undermining the business case for new large-scale transportation infrastructure projects such as the proposed Ring 5 in Copenhagen and the Columbia River Crossing project in Portland.
The path dependencies embedded within large-scale transportation infrastructure projects have dramatically different carbon trajectories, depending on the mode. If cities and regions are to meet their aggressive carbon reduction goals, then they will have to, sooner rather than later, begin to shift their strategic investment focus away from high carbon, motorized forms of travel toward low- or no-carbon modes of travel. Such decisions may become increasingly easier to implement in light of the decaying political support and economics of massive expansions of the road network.
FULL STORY: Breaking Carbon Lock-in: Path Dependencies in Large-Scale Transportation Infrastructure Projects

Maui's Vacation Rental Debate Turns Ugly
Verbal attacks, misinformation campaigns and fistfights plague a high-stakes debate to convert thousands of vacation rentals into long-term housing.

Planetizen Federal Action Tracker
A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

In Urban Planning, AI Prompting Could be the New Design Thinking
Creativity has long been key to great urban design. What if we see AI as our new creative partner?

Cal Fire Chatbot Fails to Answer Basic Questions
An AI chatbot designed to provide information about wildfires can’t answer questions about evacuation orders, among other problems.

What Happens if Trump Kills Section 8?
The Trump admin aims to slash federal rental aid by nearly half and shift distribution to states. Experts warn this could spike homelessness and destabilize communities nationwide.

Sean Duffy Targets Rainbow Crosswalks in Road Safety Efforts
Despite evidence that colorful crosswalks actually improve intersection safety — and the lack of almost any crosswalks at all on the nation’s most dangerous arterial roads — U.S. Transportation Secretary Duffy is calling on states to remove them.
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.
Appalachian Highlands Housing Partners
Gallatin County Department of Planning & Community Development
Heyer Gruel & Associates PA
Mpact (founded as Rail~Volution)
City of Camden Redevelopment Agency
City of Astoria
City of Portland
City of Laramie