The Katy Freeway outside Houston is a symbol of the embodiment of American car culture. After a nearly $ 3 billion expansion project completed in 2008, the highway spans 26 lanes at its widest point (although some argue whether you should count the peripheral frontage roads).
But it also symbolizes something else: a transportation phenomenon called induced demand – the idea that building more infrastructure will only drive more demand. In this case, the supply is highway lanes and the demand is more and more drivers. Meaning: If you build more highway lanes, more drivers will fill them.
The concept of induced demand has been around since the 1960s – almost as long as the beginnings of the federal road network – and has since been proven by several studies. But it still hasn’t turned the tide of large, expensive highway infrastructure projects as a patch for congestion.
Today, transportation is the leading cause of US greenhouse gas emissions, largely due to the use of a car for one person. Most American cities are all about the car, which is why it is difficult to adapt any other system that focuses on transit or walking. But there are policies that can get more people off the highways in the short and long term.
In this video, we explain what happens after a highway extension and where new drivers come from to fill new lanes.
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