It's about human beings in a densely populated urban area.
Streets are about economics and urban design more than engineering, by Robert Steuteville (Better Cities)
... Recognizing that most trips are economic decisions and that people have choices puts a whole new spin on roads and traffic. As Hertz of City Observatory says:
"The economic, or behavioral, approach brings back humans—and with them, the idea that given amount of vehicle trips isn’t just a feature of the natural world, but the result of decisions by actual people who want to get somewhere in order to do something. The question then changes in a subtle but profound way: not how to speed vehicles through a road most efficiently, but how to best connect people with the places they want to go."
"Bringing humans back into the question also allows you to acknowledge that people have desires that aren’t directly related to transportation. Safety, for example. Reducing the number and length of vehicle trips translates straight to fewer car crashes, and fewer avoidable serious injuries and deaths. Making streets a pleasant place to walk and gather—something that’s difficult when sidewalks have been narrowed to make room for speeding cars just feet away—can pay serious economic dividends and help establish a sense of community. In the economic or behavioral approach to transportation policy, all of these goals suddenly become fair game."
Viewing congestion as an economic problem may also get transportation engineers to recognize that congestion is often good. The bad kind of congestion is when people are just sitting in traffic and little economic activity is taking place. But in a mixed-use downtown, congestion is a sign of life ...