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Detailed Justification for Nationwide Differential Global Positioning System (NDGPS) Program

Detailed Justification for Nationwide Differential Global Positioning System (NDGPS) Program

FY 2008 Request: $5,000,000


Among current U.S. positioning, navigation and timing (PNT) systems, the Nationwide Differential Global Positioning System (NDGPS) is an enabling technology for civil, commercial and scientific applications.  Fifty nations have followed the U.S. lead by building compatible NDGPS systems.  This is a mark of success of the National Space-Based PNT policy for promoting the use of GPS, GPS augmentation systems such as NDGPS, and PNT-based civil, commercial and scientific applications worldwide.

DOT, in cooperation with the U.S. Coast Guard (USCG), the U.S. Air Force, the U.S. Army Corps of Engineers, and the National Oceanic and Atmospheric Administration (NOAA), has partially deployed and operates the NDGPS service in the U.S.  NDGPS provides accurate dynamic navigation information to users with one-to-two meter accuracy.  As the accuracy of GPS has improved, particularly through removal of Selective Availability, the operational need for NDGPS has diminished.

Despite DOT program responsibilities for NDGPS, there are no current validated transportation systems requirements for NDGPS.  The majority of current NDGPS users appear to be primarily in the resources management community (e.g., agriculture, surveying, forestry).  While some potential future transportation applications have identified a High Performance NDGPS capability as a possible enabling technology solution for high accuracy (decimeter level) operational requirements, notably in Intelligent Transportation Systems (ITS) applications, these requirements, and the application deployments, are uncertain.

The government has invested $53.7 million to date for NDGPS (not including in-kind contributions of land and equipment from federal and state partners). This investment needs to be preserved while assessments of inland requirements for NDGPS are completed, and options for meeting the high accuracy PNT requirements of future transportation applications are evaluated.  These activities will be evaluated in conjunction with the National PNT Architecture effort to determine to what extent the NDGPS infrastructure can meet user needs as part of a national PNT architecture, before any decision on the future maintenance, operation or enhancement of the system is made.

Need for the Civil PNT Architecture Program:

Reliable PNT services are essential elements of the national transportation critical infrastructure, and involve multiple technologies that support multi-modal systems safety operations requirements and other applications.  The U.S. Space-Based PNT Policy states that the U.S. must continue to improve and maintain GPS, GPS augmentation, and back-up PNT capabilities to meet constantly increasing national, homeland, and economic security requirements, as well as operational missions of the broader civil, commercial, and scientific communities.

The National Space Policy Directive (NSPD-39) identifies DOT as the focal point for representing and assuring civil GPS requirements.  However, DOT faces significant challenges in harmonizing and coordinating systems requirements and research for improved use of PNT services, development of augmentation systems, and assurance of PNT systems back-ups.  Without a management structure to coordinate research and systems assessment activities, there is risk of duplicated efforts and misapplied resources.

In order to avoid PNT solutions developed for individual user applications, the Under Secretary of Transportation requested that RITA lead DOT’s efforts in the development of the National PNT Architecture on behalf of the civil community.  Development of the national PNT architecture will require a coordinated approach from all sectors of the civil community to determine the most efficient and effective mix of systems to meet future civil user PNT requirements.  The architecture effort involves close coordination with the other civil departments and agencies and, in particular, with Office of the Secretary’s Office of Navigation and Spectrum Policy for policy decisions that result from the systems architecture study.

The system engineering activities performed in development of the National PNT Architecture will determine the best method to meet the future high performance PNT needs of the transportation community, including back-up systems, and identify the potential role of NDGPS as part of this national architecture.

FY 2007 Base

The funding base in FY 2007 for the NDGPS Program, in the Federal Railroad Administration (FRA) budget request, was $0.  The Department decided to carry forward FY 2006 funding to manage FY 2007 NDGPS operations and maintenance expenses of the NDGPS sites at a low level to preserve the government investment in the system, while assessing the new responsibilities assigned to the Department by the U.S. Space-Based PNT Policy, including current and potential future NDGPS requirements.

Anticipated FY 2007 Accomplishments

RITA and FRA will coordinate continued delivery of NDGPS user services, through a Memorandum of Agreement with the USCG, but will not expand the system or otherwise pursue system buildout.  On behalf of DOT, RITA will coordinate completion of the technical assessment for the need for the inland component of NDGPS, including assessing interagency system requirements and seeking validated transportation requirements.  From this assessment, policy determinations will be made about continuing, mothballing, or decommissioning NDGPS.

A PNT system engineering analysis will be initiated to address the best methods to meet civil PNT requirements.  This analysis will be performed in conjunction with the development of a National PNT Architecture that will determine the future role of NDGPS as part of this architecture. 

FY 2008 Budget Request

The funding and program management responsibility for the NDGPS Program resided in the FRA budget through FY 2007.  RITA has agreed with FRA to coordinate the NDGPS requirements assessment and NDGPS operations in FY 2007.  If funding is received in FY 2008 to continue NDGPS operations, and a policy determination made to continue NDGPS, then NDGPS program management will be transferred from FRA to RITA.

In FY 2008, RITA will fund NDGPS operation and maintenance of existing NDGPS sites through a Memorandum of Agreement with the U.S. Coast Guard (USCG) to preserve the government investment in this system, and to support current NDGPS system users.  No construction or new equipment installation for NDGPS will be pursued, pending the results of the NDGPS assessment and follow-on decisions.

RITA will perform system engineering activities in support of developing the National PNT Architecture that will determine the best method to meet the high performance PNT needs of the transportation community, and to identify the future role of NDGPS as part of this national architecture.

NDGPS Operations and Maintenance (O&M)

Excel | CSV

Task Cost
Atlantic Support Manager O&M $2,270,582
Pacific Support Manager O&M $101,650
Systems Management $1,010,000
Navigation Center (NAVCEN) $200,000
National Geodetic Survey (CORS) $381,717
NOAA Earth System Research Laboratory $295,623
Parts Support/Depot Level Repair $25,000
Emergency/Operational Contingency $315,428
Total NDGPS Operations and Maintenance $4,600,000

PNT Architecture System Engineering

Excel | CSV

Task Cost
Civil User Needs Evaluation $125,000
PNT Civil Technology Assessment $175,000
Future Civil Environment Definition $100,000
Total PNT Architecture System Engineering $400,000

Explanation of Funding Changes for NDGPS Program

Amount: +$5,000,000:

Excel | CSV

Summary Cost
Total NDGPS Operations and Maintenance $4,600,000
Total PNT Architecture System Engineering $400,000
Total Requested $5,000,000

The increase in funding reflects a Departmental decision in the FY 2007 budget request to reschedule FY 2006 program funding across two fiscal years, and to continue this function in FY 2008 by transferring the NDGPS program from FRA to RITA (pending funding availability and decision to continue operations).  The cost to operate and maintain the NDGPS sites in a “preservation of investment” state is $4,600,000; this budget assumes no expansion or construction activities.  System engineering work on development of a national PNT architecture to support future high performance transportation PNT requirements is $400,000.