@coolboymew Traffic flow control.
without "clover leaves," a lot of high-traffic highway exits will get so backed up they'll disrupt traffic on the street.
There used to be this on-ramp, not far from where I used to live, where the highway was pretty close to a train station (as in an intra-city train station) and between the train stopping traffic on the road, and cars backed up getting on the freeway, the street would backed up for miles sometimes.