If You Build It, the Cars (and the Pollution) Will Come

RMI analysis indicates that Colorado's plans to add approximately 200 new highway lane-miles over the next decade will likely increase vehicle miles traveled (VMT) and greenhouse gas emissions, contradicting the state's climate goals. The report introduces an induced travel calculator to quantify these impacts, suggesting that road expansion fails to provide long-term congestion relief and instead encourages more frequent and longer trips.

• Road expansions generally fail to provide lasting congestion relief, as any benefits typically disappear within 5 to 10 years because travel demand increases proportionally to the new capacity.
• In Colorado's urbanized areas, each new highway lane-mile is estimated to increase traffic by 2 to 8 million VMT per year. Using a midpoint estimate, one added lane-mile equates to approximately 400 additional cars and SUVs on the road annually and the carbon pollution of about 200,000 gallons of gasoline.
• A review of high-profile planned and in-progress projects in Colorado suggests that 176 new highway lane-miles could be added by 2030, potentially leading to 1 to 1.5 billion additional VMT per year. This represents a roughly 2 percent increase over current VMT, equivalent to adding about 70,000 more vehicles annually.
• The portfolio of planned road expansions in Colorado is estimated to increase direct and upstream greenhouse gas emissions by 8 to 15 million tons of CO2-equivalent cumulatively through 2050, with total direct costs for these projects exceeding $3 billion.
• To achieve a safe climate future, RMI analysis suggests the United States must reduce passenger vehicle travel by 20 percent per capita by 2030, alongside the adoption of electric vehicles.

APA

RMI (2021). If You Build It, the Cars (and the Pollution) Will Come. https://rmi.org/resources/if-you-build-it-the-cars-and-the-pollution-will-come/

Chicago

RMI. If You Build It, the Cars (and the Pollution) Will Come. 2021. https://rmi.org/resources/if-you-build-it-the-cars-and-the-pollution-will-come/.

Wikipedia

{{cite report |author=RMI |title=If You Build It, the Cars (and the Pollution) Will Come |date=21 April 2021 |url=https://rmi.org/resources/if-you-build-it-the-cars-and-the-pollution-will-come/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{rmi2021you, author = {{RMI}}, title = {{If You Build It, the Cars (and the Pollution) Will Come}}, institution = {RMI}, year = {2021}, month = apr, url = {https://rmi.org/resources/if-you-build-it-the-cars-and-the-pollution-will-come/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }