One might assume that a wider road allows traffic to flow more smoothly by allocating the same number of vehicles more space. This argument contains a fatal flaw: When roads get wider more people start driving, a phenomenon known as “induced demand”. People drive when they used to bike, walk, or take public transit; they move further away from their jobs in town and drive further to get there; they drive in rush hour when they used to drive at other times; and businesses that depend more on roads will relocate to cities, bringing more truck traffic with them.
Reading the article, I was reminded of the many discussions I have heard about workflow management, and how limiting work-in-progress will, counterintuitively, typically increase a team’s productivity.
That analogy seems even more apt as, later in the article, the author gets to road designs that do actually ease congestion:
The evidence is that streets with bike lanes, bus-only lanes, wide sidewalks, and (if they must be there) car lanes carry over twice as many people per hour and thus decrease travel times as streets designed for just cars. This is because biking, busing, and walking consume much less space per person and encourage more compact development, reducing traveling distances.
Now I find myself wondering what the effect would be of closing off a block or two of my town's downtown to cars.