Grade separation is a method of aligning a junction of two or more roadway axes at different heights (grades) so that they will not disrupt the traffic flow on other transit routes when they cross each other. The grade separation can consist of a mixture of roads, bridges (overpasses or flyovers), tunnels (underpasses), footpaths, railways, canals or airport runways. Three primary roadway improvement objectives are accomplished using grade separated intersections: 1) increased capacity and uninterrupted flow, 2) increased safety and 3) reduced vehicle conflicts and delay.

Grade Separation illustration

Illustration: Grade Separation

 

Grade Separation photo

Photograph: Grade Separation

A. US 281 Mainlanes (Overpass)

B. SH 46 Intersecting Road (Underpass)