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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

High Accuracy Global Positioning System Test: Phase II

Document Series
Technical Reports
Federal Railroad Administration
Report Number
Subject Positive Train Control
High Accuracy Nationwide Differential Global Positioning System, HA-NDGPS, High Accuracy Global Positioning System, GPS, Positive Train Control, PTC

The High Accuracy Nationwide Differential Global Positioning System (HA-NDGPS) is a prototype position location service that uses carrier phase and code measurement data to obtain precise geolocation information. This project was established to assess the feasibility of improving upon the accuracy of the NDGPS service using existing infrastructure to meet the requirements of additional applications without decreasing its availability and integrity, while still meeting the needs of existing users. The Transportation Technology Center developed this project to independently test the ability of the high accuracy portion of the HA-NDGPS system to achieve sub decimeter positional accuracy with only relatively minor modifications to an existing NDGPS site. This high accuracy capability may provide a low-cost positioning solution for railroad systems, such as Positive Train Control (PTC), which require precise tracking of trains in real time to ensure operational safety. Another railroad-related benefit may be the more efficient collection of track feature information needed for generating and maintaining track databases that support PTC operations. Other transportation applications include Federal Highway Administration applications such as those defined by the Vehicle Infrastructure Integration project of the Intelligent Transportation Systems initiative.

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Last updated: Friday, May 21, 2021