Which type of interchange connects two controlled access highways or freeways without at-grade intersections at ramp terminals?

A directional interchange effectively allows two controlled access highways or freeways to connect seamlessly without any at-grade intersections at the ramp terminals. This design prioritizes smooth traffic flow, particularly for high volumes of vehicles, by minimizing conflict points where vehicles might otherwise need to stop or slow down to yield.

In a directional interchange, the ramps are designed to handle traffic efficiently by allowing movements between the highways without mixing with other traffic flows, such as local roads. This setup reduces delays and increases safety, making it ideal for busy freeway connections.

On the other hand, interchanges like the full cloverleaf, diamond, and partial cloverleaf all involve at-grade intersections or have configurations that might lead to delays or intersections where traffic may need to yield or stop, which is contrary to the requirement described in the question.