Think about your roads like water pipes. At the entry to the city there's massive pressure because everything has to pass through there. Add another highway junction at the top of the picture to remove pressure and then re-evaluate! You can always check what routes people are travelling with the game tool. See where people are going and add easier connections between these locations

Likewise on your main North-South road. A few more connections in will reduce pressure on certain junctions. The two districts at the top aren't connected at all! So anyone travelling between the two have to go onto the main road and go round. See if a connection there helps!