Global Positioning System (GPS): A system that identifies latitude, longitude, and elevation; a hand console is used to obtain data from an orbiting satellite.

Grade: The slope parallel to the direction of travel that is calculated by dividing the vertical change in elevation by the horizontal distance covered. For example, a trail that gains 2 m in elevation over 40 m of horizontal distance has a grade of 5 percent.

Grade-separated crossings: Facilities such as overpasses, underpasses, skywalks, or tunnels that allow pedestrians and motor vehicles to cross a street at different levels.

Graphical User Interface (GUI): Program interface that presents digital information and software programs in an image-based format as compared to a character-based format.

Grate: A framework of latticed or parallel bars that prevents large objects from falling through a drainage inlet but permits water and some sediment to fall through the slots.

Gutter: A trough or dip used for drainage purposes that runs along the edge of the trail or street and curb or curb ramp

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