You could try a frontage roadfrontage road running parallel to your large one way:
Wikipedia article on frontage roads
This allows for numerous entry and exit points to the highway without making a zillion intersections on your main avenue. The frontage road also "filters" the traffic to closer to where they actually want to go instead of having them all go in and out at the same place.
Here's a screenshot of one I made in game:
It's a bit goofy because I didn't have room to run on both sides of the highway but flows very well.