An ovoid-curve ramp is useful when an interchange ramp needs to tighten gradually within limited space. In this example, vehicles enter a larger R=90m arc, pass through a transition curve, then enter a smaller R=60m arc before joining the mainline entrance.
This guide explains how to connect independent roads and build entrance ramps, exit ramps, and complete right-turn ramps for an interchange. The core idea is to combine straight segments, transition curves, and circular curves so vehicles can leave one main road smoothly, pass through the bend, and merge into another main road.