There really isn't a solution to
LA's traffic woes, other than massive depopulation. It has too high of a population density to support the car-centric development, but as most of the development is car-centric there isn't much chance of reducing the number of cars on the road. That can and will change over time (and has to some degree), but adding a couple more freeway lanes here and there at great expense isn't going to help. Nor would building my fantasy subway network overnight if such a thing were possible. Development patterns have to change.