More lanes → more people driving + more people taking that specific route → problem gets worse.
Usually a better approach is to invest on mass transport; for example even if a bus takes the space of three cars (I’m guessing), it’s able to comfortably transport at least 20 people.
Sadly, any sort of mass transportation system is also prone to the same sort of vicious cycle; for example, if queue time for buses is too long, people will avoid taking them unless strictly necessary, so their usage is lower, so the companies put even less buses on those lines, so queue times increase even more. It’s basically what happened in my city (Curitiba), that used to have a fairly decent mass transport system.