Automatic Vehicle Location (AVL)

Automatic vehicle location is a means for determining the geographic location of a vehicle and transmitting this information to a point where it can be used.

Most commonly, the location is determined using GPS and the transmission mechanism is a satellite, terrestrial radio or cellular connection from the vehicle to a radio receiver, satellite or nearby cell tower.

The tracking data is then transmitted using any one of a variety of telemetry systems. GSM and EVDO are the most common technologies used for telemetry because of the low data rate needed for AVL. The low bandwidth requirements also allow for satellite technology to receive telemetry data at a moderately higher cost, but across a global coverage area and into very remote locations not well-covered by terrestrial radio or public carriers.

Automatic vehicle location is a powerful tool for managing fleets

Vehicles such as service vehicles, emergency vehicles, and construction equipment and public transport vehicles (buses and trains) are all using automatic vehicle location (AVL) systems or GPS tracking systems. It also is used to track mobile remote assets such as construction equipment, trailers, and portable power generators.

Types Of AVL Systems

Direction Finding

Amateur radio and some cellular or PCS wireless systems use direction finding or triangulation of transmitter signals radiated by the mobile. This is sometimes called radio direction finding, or RDF. The simplest forms of these systems calculate the bearing from two fixed sites to the mobile. This creates a triangle with endpoints at the two fixed points and the mobile. Trigonometry tells you roughly where the mobile transmitter is located. In wireless telephone systems, the phones transmit continually when off-hook, making continual tracking.

Signpost Systems

To track and locate vehicles along fixed routes, a technology called signpost transmitters was employed. This is used on transit routes and rail lines where the vehicles to be tracked continually operated on the same linear route. A transponder or RFID chip along the vehicle route would be polled as the train or bus traverses its route. As each transponder was passed, the moving vehicle would query and receive an ark, or handshake, from the signpost transmitter. A transmitter on the mobile would report passing the signpost to a system controller. These systems are an alternative inside tunnels or other conveyances where GPS signals are blocked by terrain.

How Automatic Vehicle Location Systems Work

Automatic Vehicle Location, or AVL, is a setup that reports a vehicle’s position back to a central dashboard. Most avl systems use GPS plus a cellular connection to send real time location data at set intervals. Dispatch sees each unit’s real time location and exact location on a map, along with basic status signals like moving, stopped, or idling. In larger deployments, AVL pairs with computer aided dispatch so the dispatcher can assign the closest unit, adjust coverage, and keep service moving when conditions change.

This is especially common for transit vehicles and public fleets, where agencies need consistent updates across long routes and multiple depots. AVL can also push data into customer facing tools, including mobile apps, when a system supports rider updates and ETA sharing.

Benefits of Automatic Vehicle Location for Fleets

AVL improves fleet management because it replaces guesswork with real time visibility. When you can monitor vehicles continuously, it becomes easier to spot route drift, missed turns, and long dwell times, then optimize routes without waiting for end of day reporting. Over time, this supports optimizing route planning and strengthens operational efficiency because dispatch decisions happen faster and drivers spend less time backtracking.

AVL can also help reduce fuel consumption by tightening routes, cutting idle time, and limiting unnecessary miles. Service teams often see better arrival accuracy, which can improve service quality and protect overall service quality in high volume operations. For public sector use cases, AVL plays a big role in emergency services, where dispatch needs fast unit selection and reliable location awareness during response and coverage planning.