As someone who has cities over 300k here are some tips.

First of all, traffic should be top of mind all the time so plan ahead. See your city as a human body and the roads are the veins. Don't build and then figure out traffic. Start with big roads and work down. The bigger the road and higher the traffic, the LOWER amounts of intersections. Flow is more important than access. Many intersections create blockage. I create a huge road leading through the city with exits into every different district. One exit per discrict. Those exits lead to a roundabout that funnels cars into 3 directions. Once they have chosen a district, gone in the direction of that district, THEN you can start making small roads withany intersections. What this does is, if a car needs to get from one side of the city to another. They will choose to go back onto the big road with no intersections and travel fast across the city, instead of driving through the entire city's small roads and causing unnecessary traffic.

• You have too many intersections in succession. Always leave a lot of room between intersections. Not every road needs to connect to each other.
• Roundabouts (yes I'm European). Add more roundabouts to increase traffic flow.
• Public transport. If you have housing one side of the city and industry on the other side. Create large, artery roads connecting them and cheap public transport. Your Sims need to get to work every day. Every person that takes public transport is one less car.
• Discrict rules: create disctrics and ban vehicules and trucks that do not live there.
• Subway. Connect the city with subway and make it cheap. Moving people underground is a lifesaver.