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From what I can tell, you have about ten time the amount of industry for a city that size and it's flooding you roads with traffic. Plus you have a lot of isolated districts that cause traffic issues with limited road access.
Watch you exports. You want zero exports.
Watch your import. You don't want to import goods. Goods are created by generic industry.
Remember that traffic flow is the most important part of keeping the city jam-free. A lot of people think if they build bigger roads, this will mean they can handle more traffic. This generally isn't the case. Extra lanes really add a negligable amount of capacity to your roads. What you want is faster, freer flowing roads. Don't get me wrong, there's a place for more lanes, they're good at holding extra traffic to reduce tailbacks at traffic lights and more lanes can, in certain situations, allow your traffic to flow more smoothly, reducing queueing by splitting traffic queues by destination. But simply having more space on your road so it can hold more cars by itself does little-nothing to improve traffic flow, it just fractionally delays the amount of time it takes to build up horrendous tailbacks. Building big roads is something you should actually consider, it shouldn't be the default reaction to traffic jams.
Re-routing traffic onto freer-flowing roads is key and limiting the amount of traffic that flows down any given standard intersectioned road Is what you want to be aiming for. Disperse the traffic from your arterial highways onto your general road network in small doses.
I'm assuming "Heather Heights" is your industrial area (I can't see a damn thing in the first photo, use screenshots or at least turn the flash off on your camera). It looks like all the truck traffic is being funneled onto 2 roads feeding a roundabout and the backup is being caused by that intersection. I suggest removing the roundabout and having that single main road lead straight to the highway with as few intersections as possible, and remove that eastern road's access to the main road in that area (have it intersect further north).
The other option is to keep the roundabout but remove all the traffic lights on it, and use a highway instead of a regular street to build the roundabout itself. Honestly though I would have placed the roundabout further north as a funnel to feed the main road within the actual industrial area. But either of these should help.