> Where do you put the "more car lanes"?

I'm not very familiar with Houston, but a quick google search shows that there is a big project underway right now to add more lanes in Houston [1]. So it would seem that civil engineers there have found a place to put more car lanes that they think will help with traffic congestion.

> At which point do you have enough car lanes?

As long as Houston is growing (currently it is the second fastest growing city in the US), I don't think there will ever be enough. They need to continuously improve their transportation infrastucture to keep up with a growing population. As I said above, I think this should include bike lanes and public transportation too. But if engineers identify a solution to alleviate traffic congestion by building more roads, then I think that is worth considering, too.

[1] https://www.txdot.gov/about/newsroom/local/houston/i45-const...