Interstate 45 in Houston is undergoing a $13-billion expansion to reduce congestion by adding new lanes. This approach is not unique, as similar projects are underway across the U.S., such as the $4.5-billion I-35 widening in Austin and a nearly $500 million expansion of I-80 near Sacramento. A significant project on the New Jersey Turnpike is expected to cost $10.7 billion.
Despite these efforts, experts suggest that such expansions may not provide long-term relief from traffic congestion due to a phenomenon known as induced demand. Susan Handy, a transportation engineer at the University of California, Davis, explains: “Congestion gets better for a little bit…, and then we’re back to where we were.” This cycle raises questions about how far road expansions can go before becoming ineffective.
Induced demand occurs when increased road capacity encourages more driving, eventually leading to renewed congestion. Kelcie Ralph, a transportation planning researcher at Rutgers University, notes that people adjust their behavior based on traffic conditions, which affects their travel choices. Mark Burris from Texas A&M University adds that even if congestion returns, widened highways can still accommodate more vehicles, benefiting drivers who prefer these routes.
However, the benefits of highway expansions come with costs such as high expenses for construction and maintenance and negative impacts on health and the environment due to increased pollution. These issues often disproportionately affect communities of color living near urban highways.
Urban planners like Ralph and Handy argue for diversifying transport options instead of relying solely on road widening. Ralph suggests investing in alternatives like mass transit or safe biking paths rather than committing resources to infrastructure that doesn't align with future needs.
Congestion pricing emerges as an alternative solution that cities are adopting nationwide. Unlike widening roads, congestion pricing manages driving costs in specific areas to control traffic levels. Programs like those in New York City include tolls for entering busy zones. High-occupancy toll (HOT) lanes offer another option where drivers pay for faster-flowing lanes while others benefit from reduced overall congestion.
These programs are less costly than highway expansions and generate revenue for other transportation investments. Although initially challenging to implement due to direct costs faced by drivers, public approval tends to rise once effectiveness is observed. Burris states: “When people see it, they like it—time and time again,” echoed by Ralph’s observation of rising approval ratings post-implementation.
While highway widening isn't always unfavorable, Ralph emphasizes evaluating both benefits and drawbacks realistically before deciding on expansions: “I just want us to make conscious choices that consider the sort of pros and cons” based on likely outcomes rather than assuming additional lanes will solve gridlock issues.
