I delete/ redesign problem junctions alot of the traffic often stems from 1 junction. If you have tram station then a tram depo next to each other with 2 junctions in close proximity, the AI seem to wait till the junctions are clear before driving through this leads to just 1 car going through the section at a time and a build up of traffic in both directions, so I just delete the tram depo and the traffic moves free again.
Don’t delete the city to city links, build more, my hub city is where 3 lines terminate, so I built a road going to the first city on each of the lines (1 was already in place) it spread the road traffic out and despite a pop of 1200 the city is traffic free and still 85% line usage,