Gulyás Katalin et al. (szerk.): Tisicum. A Jász-Nagykun-Szolnok megyei Múzeumok évkönyve 28. (Szolnok, 2020)

Történettudomány - Csaba Kasza: Evolution and human benefits of the GPS

CSABA KASZA: EVOLUTION AND HUMAN BENEFITS OF THE GPS

of locomotives, rail cars, maintenance-of-way vehicles, and wayside equipment. Rail systems in many parts of the world are increasingly using the GPS in combination with various sensors, computers, and communication systems to improve safety, security, and operational effectiveness.

Unlike most other modes of transportation, there is little flexibility in managing rail traffic. Most rail systems are comprised of long stretches of a single set of tracks. Trains must simultaneously share the use of these single line tracks. It is therefore critical for safety and efficiency reasons to know the position and performance of these trains both individually and system-wide. Only the skill of the crews, accurate timing, a dynamic dispatching capability, and a critical array of “meet and passes” locations on short stretches of parallel tracks, allow rail dispatchers to guide their trains safely.

When coupled with other location and navigation devices to account for time in tunnels, behind hills, and other obstructions, GPS can provide a reliable and accurate position-locating capability for rail traffic management systems, and it has become an essential element of the Positive Train Control (PTC) concept now being adopted in many parts of the world. This involves providing precise railroad position information to sophisticated command and control systems to produce the best operating plan, to include varying train speed, re-routing traffic, and safely moving maintenance crews onto and off tracks. PTC increases operational efficiency, allows higher track capacity, enhances crew, passenger, and cargo safety, and also results in a safer environment for personnel working on the track. In short, GPS helps to reduce rail accidents, delays, operating costs, and dangerous emissions, while increasing track capacity, customer satisfaction, and cost effectiveness.

Roads and Highways. The availability and accuracy of the GPS offers increased efficiencies and safety for vehicles using highways and streets, and for mass transit systems. It is estimated that delays from congestion on highways, streets, and transit systems throughout the world result in productivity losses in the hundreds of billions of euros annually. Other negative effects of congestion include property damage, personal injuries, increased air pollution, and inefficient fuel consumption.

Many of the problems associated with the routing and dispatch of commercial vehicles, mass transit systems, road maintenance crews, and emergency vehicles are significantly reduced or eliminated with the help of GPS. GPS-enabled automatic vehicle location and in-vehicle navigation systems are widely used throughout the world today, significantly reducing time lost and environmental impacts due to mis-routing or unfamiliarity with locales. By combining GPS position technology with systems that can display geographic information or with systems that can automatically transmit data to display screens or computers, a new dimension in surface transportation is realized.

Today geographic information systems (GIS) store, analyze, and display geographically referenced information provided by GPS. Mass transit systems use this capability to track rail, bus, and other services to improve on-time performance. Instant car pools are feasible since people desiring a ride can be instantly matched with a vehicle in a nearby area. Using GPS technology to help track and forecast the movement of

freight has made a logistical revolution, including an application known as time-definite delivery. In time-definite delivery, trucking companies use GPS for tracking to guarantee delivery and pickup at the time promised, whether over short distances or across time zones.

Many nations use GPS to help survey their road and highway networks and identify the location of features on, near, or adjacent to the road networks. These include service stations, maintenance and emergency services and supplies, entry and exit ramps, damage to the road system, etc. This helps transportation agencies reduce maintenance and service costs and enhances the safety of drivers using the roads. In the future, GPS will provide for even more effective systems for crash prevention, distress alerts and position notification, electronic mapping, and in-vehicle navigation with audible instructions.

Survey and Mapping. GPS is rapidly being adopted as the standard by professional surveyors and mapping personnel throughout the world. Using the near pinpoint accuracy provided by the GPS and its augmentations, highly accurate surveying and mapping results can be obtained very rapidly, significantly reducing the amount of equipment and labor hours required with conventional surveying and mapping techniques. Today, it is possible for a single surveyor using GPS to accomplish in one day what used to take weeks with an entire team.

Unlike traditional techniques, GPS surveying is not bound by constraints such as line-of-sight visibility between reference stations, and the spacing between stations can be increased. The increased flexibility of GPS also permits survey stations to be established at easily accessible sites rather than being confined to hilltops as it was previously required. Remote GPS systems may be carried by one person in a backpack, mounted on the roof of an automobile, or fastened atop an all-terrain vehicle to permit rapid and accurate field data collection. With a GPS radio communication link, real-time, continuous centimeter-level accuracy makes possible a productivity level that is virtually unattainable using optical survey instruments.

Timing. Precise time is crucial to many business activities throughout the world. Communication systems, electrical power grids and financial networks all rely on precision timing for synchronization and operational efficiency. The heart of the GPS system is the family of atomic clocks carried on each satellite and continually updated from an ensemble of ground atomic clocks. That is compared with the world-standard maintained by the US Naval Observatory to an accuracy of one nanosecond. As a result, the Universal Coordinated Time (UTC) is disseminated globally by GPS, specified accuracy within 100 nanoseconds but in practice accuracy within 10 nanoseconds.

The applications of this incredibly accurate, universal timing signal have resulted in GPS becoming one of the world most critical infrastructures and the only one that is provided at no cost to users everywhere. Among them are frequency standards for 50 and 60 hertz power systems; synchronization of computer networks for billing and communications; use by communications systems for frequency and phase timing; simultaneous observations by astronomic radio and optical observatories and very long baseline interferometry systems.

235