Better highway capacity would help some.  One of the big (but oft-ignored) side effects of insufficient-capacity highways is vehicles spilling over onto other main streets and side roads (even residential streets) traveling longer distances than they were intended to be used for.  Such drivers trying to just get THROUGH a neighborhood (rather than just moving short distances within their own neighborhood) tend to be far less patient.  And probably a bit pissed that the highways that they should be and want to be using are so jammed up.