The Katy Highway outside Houston symbolized the epitome of American automotive culture. Following a $ 3 billion expansion project completed in 2008, the highway spans 26 lanes at its widest point (though some dispute whether you should count the peripheral highways).
But it must also symbolize something else: a transport phenomenon called induced demand – the idea that building more infrastructure will only encourage more demand. In this case, the supply is highways, and the demand is more and more drivers. Meaning: if you build more highways, more drivers will fill it.
The concept of induced demand has existed since the 1960s – almost as long as the emergence of the federal highway system – and has since been proven by several studies. But it still has not stopped the flood of large, expensive highway infrastructure projects as a patch for congestion.
At present, transportation is the leading cause of greenhouse gas emissions in the US, and it is mainly driven by the use of single-person cars. Most American cities revolve around the car, which is why it is difficult to adapt to a different system that focuses on transportation or walking. But there are some policies that could get more people off the highway in the short and long term.
In this video, we explain what happens after a highway expansion, and where new drivers come from to fill new lanes.
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