Induced Demand, Explained

CityLab University endeavors to provide clear explanations of some of the "most important concepts related to cities and urban policy." A previous post explained inclusionary zoning, for instance. For the most recent post, Benjamin Schneider explains the concept of induced demand, or why new road capacity doesn't reduce traffic.

Launching the explanation with the example of the Katy Freeway in Houston, which has 26 lanes at its widest point, and still sees worsening congestion.

The idea that the Katy Freeway could expand to such capacity and still see regular congestion is explained by induced demand. While Schneider goes into a lot more detail in the source article, here are the key points that organize the article:

• In urbanism, “induced demand” refers to the idea that increasing roadway capacity encourages more people to drive, thus failing to improve congestion.
• Since the concept was introduced in the 1960s, numerous academic studies have demonstrated the existence of ID.
• But some economists argue that the effects of ID are overstated, or outweighed by the benefits of greater automobility.
• Few federal, state, and local departments of transportation are thought to adequately account for ID in their long-term planning.