Global Positioning Systems

This lead state team has completed all planned activities and is no longer active. The information below, as created by the active lead state team, remains available for review by users seeking additional information.
photo of survey equipment in a field with a mountain in the near distance

What is a Global Positioning System?

GPS is a space-based, radio-navigation system that provides worldwide, all-weather, three-dimensional position, velocity, navigation, and time data to both civilian and military users. Potential uses for GPS within the highway community are diverse and range from providing traveler information to mapping (GPS technology can be integrated easily with Geographic Information Systems).

GPS can provide a very accurate digital map of the highway infrastructure. The technology operates on the principle of triangulation—if the difference from an observer to three known points can be measured, the position of the observer can be calculated. The system includes at least 24 satellites in orbit 19,320 kilometers (12,000 miles) above the earth and inclined at 55°. These satellites continuously broadcast their position, a timing signal, and other information. By combining the measurements from four different satellites, users with receivers can determine their 3-dimensional position, currently within 4–20 meters (13–66 feet).

Benefits

Compared to conventional surveying technology, GPS:

  • Is faster.
  • Requires less labor.
  • Requires less training.
  • Is more accurate.

"GPS technology, which utilizes a constellation of satellites that transmit signals continuously, can have numerous highway applications, such as surveying pavement condition and inventorying highway assets. It offers such benefits as increased accuracy and reductions in labor, time, and costs. Utah is serving as the lead State for the initiative aimed toward use of GPS in transportation surveying applications." — FOCUS , November 2002

Contacts – Lead States Team

John McCracken
FHWA Office of Research, Development, and Technology
Pennsylvania DOT
202–493–3422
john.mccracken@fhwa.dot.gov

Charlie Brown
North Carolina DOT
217-785-9026
charliebrown@dot.state.nc.us

GPS Library