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

I got to say at least in New Orleans they increased the lanes on I-10 by two lanes and traffic flows GREAT. The bottle neck happens when we go from 5 lanes to three.

We used to have three lanes throughout and traffic would start as soon as you got on I-10 in the city all the way out through Metairie and Kenner. Now you can roll through those areas at a good pace until you get out to St. Charles.

Obviously because that improved traffic flow here that does not mean it will work everywhere but more lanes helped out a lot here.