atgrade

Atgrade, commonly written as at-grade, refers to something that exists at the same level as the surrounding ground, rather than being elevated or subterranean. In transportation planning, the term describes crossings or junctions where two routes meet on the same surface level, creating a potential conflict point for moving traffic or pedestrians.

Road use: An at-grade intersection is where roadways intersect on the surface, including cross intersections, T-junctions, and roundabouts. These junctions may be controlled by stop signs, yield signs, or traffic signals. At-grade intersections are typically cheaper to construct and easier to access adjacent land, but they can limit capacity, cause congestion, and increase the potential for collisions compared with grade-separated interchanges such as overpasses or underpasses.

Rail use: A level crossing, also called a grade crossing, is where a road or pedestrian path crosses railway tracks at the same level. Level crossings are equipped with warning devices such as flashing lights, bells, and gates, and may include additional protective measures in high-traffic areas. Where traffic volumes or speeds are high, or where a crossing sits on a busy corridor, authorities may seek to eliminate the crossing by replacing it with a grade separation, such as a road bridge or railway viaduct.

Other contexts: At-grade design can also describe facilities built at ground level, such as streets in a city grid or certain types of parking and pedestrian networks that preserve natural grade. Related terms include grade separation, level crossing, overpass, and underpass.