Traffic Surveillance > Vehicle-based Technologies > GPS

What is it?

• Global Positioning Systems (GPS) use 24 earth-orbiting satellites, GPS receivers, GPS antennas transmission towers, and Geographic Information Systems (GIS) to track the speed and location of GPS-equipped probe vehicles.
• A GPS receiver collects the real-time latitude and longitude information of a GPS-equipped vehicle and sends this information to a central computer for processing. See our Telecommunications Diagram on GPS-based In-vehicle Traffic Advisories for more information.

• Quantifying Congestion
  • Travel times collected by GPS probe vehicles can be used to quantify congestion in terms of delay or a congestion index, which in turn can be used to develop strategies to alleviate congestion.
• Travel Time Data Collection
  • In the past several years, GPS has become the preferred AVL system for fleet and travel behavior studies because it collects accurate and detailed travel times as well as captures variability in travel behavior across multiple days.
• Road Network Mapping
  • GIS software is often used in conjunction with GPS so that the positional data of a GPS probe vehicle can be viewed on a road network map.
• Civil, Commercial, and Research Applications
  • There are a variety of civil, commercial, and research applications of GPS.Transportation researchers primarily use GPS probe vehicles to determine travel times between designated points along a roadway.

• GPS probe vehicles provide accurate, detailed, real-time travel time data that can be used to detect and manage congestion problems.
• The large amounts of data collected by GPS probe vehicles is highly accurate.
• Travel time surveys can continue for multi-days, weeks, or years. This provides researchers with the data necessary for studying traffic management strategies.
• GPS are compatible with GIS software, making it easier to map out vehicle locations.

• GPS/DGPS: Capital Cost per unit: $0.5 k, Operational and Maintenance: $0.01k per year
• GIS Software: Capital Cost: $0.3k

• Privacy issues are a concern for vehicle owners who have GPS installed in their vehicles.
• Foliage, tall buildings, and tunnels can temporarily block the satellite signal, and at times satellite signals do not reach specific locations.

Where is GPS for AVL Implemented?

GPS probe vehicles are deployed in across the United States including:

• Indiana
• Boston, Massachusetts
• Baton Rouge, Louisiana
• Lexington, Kentucky
• Georgia
• Austin, San Antonio, Texas
• Chicago, Illinois
• Seattle, Washington