Automatic Vehicle Locator

Automatic vehicle location (AVL) is a computer -based vehicle tracking system. For transit, the actual real -time position of each vehicle is determined and relayed to a control center. Actual position determination and relay techniques vary, depending on the needs of the transit system and the technologies employed. Transit agencies often incorporate other advanced system features in conjunction with AVL system implementation. Simple AVL systems include: computer -aided dispatch software, mobile data terminals, emergency alarms, and digital communications.

More sophist icated AVL Systems may integrate: real-time passenger information, automatic passenger counters, and automated fare payment systems. Other components that may be integrated with AVL systems include automatic stop annunciation, automated destination signs, Vehicle component monitoring, and Traffic signal priority. AVL technology allows improved schedule adherence and timed transfers, more accessible passenger information, increased availability of data for transit management and planning, efficiency/productivity improvements in transit services .

What is AVL technology?

Automated Vehicle Locator (AVL) systems use satellite and land communications to display each vehicle's location,
status, heading, and speed on the computer's screen. AVL systems use one of four types of navigation technology, or may combine two of these technologies to compensate for inevitable shortcomings of any one technology. The four principal technologies employed for AVL systems are: 1. Global Positioning System 2. Dead-Reckoning System 3. Signpost/Odometer Systems 4. Radio Navigation/Location



The Passive Tracking System modality refers to stand -alone GPS Receivers, which store data for further process. Passive systems are typically limited to vehicle tracking only. When a Passive Tracking Device is installed in a vehicle, the location, time, velocity and heading data is usually stored in the unit or transferred to a handheld device and downloaded from the vehicle when the vehicle returns to their base station.


Real Time Tracking Systems are based on mobile stand-alone terminals which combine GPS and GSM technology to determinate and transmit their position. A two-way wireless communication link connects the unit with the control center at all times. A portable GPS tracking device can be used as an emergency cellular phone with speed dialing for two -way voice communication. It can silently call any emergency number in the world for immediate assistance. The emergency silent call feature also provides a digitized voice message which can report the time, date, speed, heading, and location of a person in distress .

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