Association of American Railroads.
A station in which the tracks and platform are either located on an aerial structure or rest directly on grade.
End point of a bridge or aerial structure.
Positive time rate change of speed of a vehicle.
An assembly of construction components elevated above the adjacent natural ground level, usually supported by columns.
Any system structure or configuration, other than a culvert, which carries tracks and spans above an earth or water surface.
A signal for attracting attention to some abnormal condition.
Support system for a rail line, such as power and electric equipment.
An entrance to a below ground station with the head of the stair or public sidewalk and the stair run within a private building structure.
At natural ground level when describing transitways or streets; the intersecting transitways and streets are at the same elevation and actually intersect. (Grade crossings that are not separated.)