Grade separation is the method of aligning a junction of two or more surface transport axes at different heights (grades) so that they will not disrupt the traffic flow on other transit routes when they cross each other. The composition of such transport axes does not have to be uniform; it can consist of a mixture of roads, footpaths, railways, c...
[n] - a crossing that uses an underpass or overpass
noun a crossing that uses an underpass or overpass