Just some random doodles on what I think I would do here, these things are always much clearer once actually in the game where you can analyze all the factors, so probably a lot of stuff I haven't thought about. But I really love thinking about these traffic layouts, like little dynamically created puzzles, I was probably one of the only people who loved the traffic in CiM2.
On the junction I would typically go for the double raised roundabouts as drawn, they basically do a similar job as the one thats already there, TBH it might actually have lower overall capacity than what you already have, just more compact and a bit cleaner and has always handled my heavy traffic areas (and it's used a lot in my RL local area so I think thats pretty neat). Probably best used if you are planning to expand to the other side of the highway as well as it spreads out the traffic better. When using this in major urban areas you might want to make sure that crossing traffic has other overpasses available so as to not interfere too much with on/off traffic.
Other than that, my changes are mostly trying to push traffic over to the next on-ramp by giving it a closer connection to the northern parts and other directions.
Also I did that little underpass/overpass connecting east/west, which is a bit random, but the sort of thing I like to use a lot, connecting different areas while bypassing the main throughfares for highway traffic. Even if they are just between residential areas they can be very good for service vehicles, school kids, etc., relieving a lot of bottlenecks by preventing "crossing of the streams" too much so to speak.
Drew some random lines on the overall city network as well:
Just more road connections with between the four major sections of your city avoiding the highway really, that's what my style of building tends towards, I see alot of people do fine when doing it differently though. As long as they are kept well clear of intersecting with major highway traffic they tend to do fine for me, and you can often just add more if they are getting clogged. Blue lines are fuzzy suggestions on the overall network for further expansion. Expanding your city can often actually help traffic by spreading it out and giving more options.
Dang, getting a real hankering for playing skylines right now. Don't know if this advice will be all to helpful once in-game, but it should illustrate some of how I personally think of road networks in the game at least.
