Vehicle traffic management systems monitor and adjust traffic systems (e.g. traffic light timing) to improve the overall flow and efficiency of traffic. Vehicle traffic management systems can use GPS information from vehicles (or the mobile phones carried by people in the vehicles) to sense the location and speed of traffic on motorways.

Figure 4 shows some of the position location applications that are enabled by the GPS system. This table shows GPS applications include mapping, location monitoring, agriculture control, navigation, NAVWAR, surveying and deformation monitoring.

Figure 4: GPS Applications

Signal availability is the ability to detect, receive and decode a transmitted signal so that some or all of the information it carries can be extracted or used. GPS signal availability is influenced by the satellite visibility and satellite health.