The "problem of soul-destroying traffic" will exist for as long as driving remains the best all-round option. It's induced demand: build more roads > capacity increases > driving becomes easier > traffic increases until driving is as hard as it was.
Add a congestion charge or tolls, and a proper public transport network. The solution is not more roads, it's fewer cars.
America suffers from one more blight: too much parking. Large chunks of LA have mandatory parking no-one needs. This spreads the city out further whilst not actually providing parking where it's needed.
Add a congestion charge or tolls, and a proper public transport network. The solution is not more roads, it's fewer cars.