Have you considered expanding your transit system with buses too? I do not have street cars, but a nice bus system took away a lot of my traffic issues. Also, maybe you should not have upgraded all of your road density so immediately. I only upgraded as needed according to the zoning growth numbers. I also wonder why you are having so much abandonment for nowhere to ship products, being in a region with two others have removed that problem completely. Are you sure that is the cause for abandonment? It could be something do with with other factors too.