Corner Radius Design

The ease of vehicle movement, especially for trucks and buses, is normally the objective of using rounded corners at intersections. Radius returns are necessary to keep traffic in their respective lanes. Because vehicle turns do not follow a perfect circular path, the most efficient design for a corner is a three-centered compound curve. A three-centered compound curve more closely follows the inner wheel track of trucks and buses than a simple, circular curve and can be used to avoid the cost of unnecessary pavement. It begins and ends with a fairly large radius curve and has a much sharper curve at the middle of the turn. The example below shows a three-centered compound curve with 120’-40’-120’radii, offset 45’.