Eli5: it’s said that creating larger highways doesn’t increase traffic flow because people who weren’t using it before will start. But isn’t that still a net gain?

Question

If people are being diverted from side streets to the highway because the highway is now wider, then that means side streets are cleared up. Not to mention the people who were taking side streets can now enjoy a quicker commute on the highway

In: Engineering

Answer 1

What they mean by “increase traffic flow” is often “lighten the amount of perceived traffic on a particular road”. So the point here is that the highway itself will still be crowded even if you expand it in an attempt to provide more space for the same amount of cars. The amount of cars in that space will just increase, not solving the original problem the expansion was trying to fix.