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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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    <item>
      <title>NextGen Works for General Aviation</title>
      <link>https://trid.trb.org/View/1413085</link>
      <description><![CDATA[The movement to the next generation of aviation is being enabled by a shift to smarter, satellite-based and digital technologies and new procedures that combine to make air travel more convenient, predictable and environmentally friendly. As demand for our nation’s increasingly congested airspace continues to grow, Next Generation Air Transportation System (NextGen) improvements are enabling the Federal Aviation Administration (FAA) to guide and track aircraft more precisely on more direct routes. NextGen efficiency enhances safety, reduces delays, saves fuel and reduces aircraft exhaust emissions. This document looks at the progress of Automatic Dependent Surveillance–Broadcast (ADS-B), Wide Area Augmentation System (WAAS), and Unleaded Fuel in general aviation.]]></description>
      <pubDate>Fri, 01 Jul 2016 09:15:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/1413085</guid>
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      <title>EGNOS and WAAS -- missing their potential in remote regions?: The example of Greenland</title>
      <link>https://trid.trb.org/View/1214022</link>
      <description><![CDATA[The introduction of a European space-based satellite augmentation system (SBAS) named EGNOS promises a strong business case by reducing communication, navigation, and surveillance cost through the replacement of precision approach NAV facilities like instrument landing system (ILS) stations at airports by permitting satellite-based approaches. Unfortunately, the system fails to cover areas that could strongly benefit from space-based augmentation, such as Greenland, for instance, a semi-autonomous dependency of Denmark which unlike the Danish state is not part of the European Union. Whilst the American WAAS system coverage ends just east of Canada, full EGNOS availability is limited to as far west as Iceland and only permits GNSS non-precision approaches with lateral guidance in Greenland. The large island is thus stuck within two SBAS systems which would be highly useful at its airports that rely heavily on expensive ground stations whilst having a thin income base. This is an illustrative example of remote regions being left out from larger-scale developments in ATM, even if they could benefit disproportionately.]]></description>
      <pubDate>Mon, 08 Oct 2012 08:47:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/1214022</guid>
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      <title>Assessment of LightSquared Terrestrial Broadband System Effects on GPS Receivers and GPS-dependent Applications</title>
      <link>https://trid.trb.org/View/1114719</link>
      <description><![CDATA[U.S. Space-Based Positioning, Navigation, and Timing Policy states that a “fundamental goal of this policy is to ensure that the United States maintains space-based positioning, navigation, and timing services, augmentation, back-up, and service denial capabilities that: (1) provide uninterrupted availability of positioning, navigation, and timing services; (2) meet growing national, homeland, economic security, and civil requirements, and scientific and commercial demands; (3) remain the pre-eminent military space-based positioning, navigation, and timing services; (4) continue to provide civil services that exceed or are competitive with foreign civil space-based positioning, navigation, and timing services.” Global Positioning System (GPS) modernization includes new signals and capabilities required to be compatible with the use of existing GPS receivers designed in compliance with specifications and standards in existence at the time of the receiver design. Compatibility with federal augmentation system (Wide Area Augmentation System [WAAS], Local Area Augmentation System [LAAS], Nationwide Differential GPS [NDGPS], and Maritime DGPS [MDGPS]) receivers in accordance with the specifications of these systems is also required. Further, in 2004, the U.S. signed an agreement with the European Union establishing cooperation between GPS and the European Galileo system. The Agreement specifically states “The Parties shall work together to promote adequate frequency allocations for satellite-based navigation and timing signals, to ensure radio frequency compatibility in spectrum use between each other’s signals, to make all practicable efforts to protect each other’s signals from interference by the radio frequency emissions of other systems, and to promote harmonized use of spectrum on a global basis, notably at the ITU.” In 2007, the U.S. Federal Aviation Administration (FAA) submitted a letter to the International Civil Aviation Organization (ICAO), in lieu of an agreement, which “reaffirms the United States Government’s commitment to provide the GPS Standard Positioning Service (SPS) for aviation throughout the world. Further, the United States commits to provide the Wide-Area Augmentation System (WAAS) service within its prescribed service volume.” The letter goes on to state that “The U.S. Government plans to take all necessary measures for the foreseeable future to maintain the integrity, reliability and availability of the GPS SPS and WAAS service and expects to provide at least six years’ notice prior to any termination of such operations or elimination of such services.” On 9 Feb 2011, the Executive Steering Group (ESG), via the National Coordination Office (NCO) of the National Executive Committee (EXCOM) for Space-Based Positioning, Navigation, and Timing (PNT), directed the National Space-Based PNT Systems Engineering Forum (NPEF) to conduct an assessment of the effects of LightSquared’s planned deployment of terrestrial broadband systems to GPS receivers and GPS-dependent systems and networks. This Report is a summary of the work conducted on this Task and includes specific Recommendations as requested by the EXCOM. Department of Defense (DoD) findings for the Task are captured separately given their security classification.]]></description>
      <pubDate>Wed, 14 Sep 2011 11:12:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/1114719</guid>
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      <title>Safety Arguments for Next Generation, Location Aware Computing</title>
      <link>https://trid.trb.org/View/1094834</link>
      <description><![CDATA[Concerns over accuracy, availability, integrity, and continuity have limited the integration of Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) for safety-critical applications. More recent augmentation systems, such as the European Geostationary Navigation Overlay Service (EGNOS) and the North American Wide Area Augmentation System (WAAS) have begun to address these concerns. Augmentation architectures build on the existing GPS/GLONASS infrastructures to support location based services in Safety of Life (SoL) applications. Much of the technical development has been directed by air traffic management requirements, in anticipation of the more extensive support to be offered by GPS III and Galileo. WAAS has already been approved to provide vertical guidance for aviation applications. During the next twelve months, the full certification of EGNOS for SoL applications is expected. This paper discusses similarities and differences between the safety assessment techniques used in Europe and North America.]]></description>
      <pubDate>Mon, 21 Mar 2011 14:13:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1094834</guid>
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    <item>
      <title>Comparison of Augmented and Non-augmented GPS Receivers for Transportation Applications: Field Survey and Analysis</title>
      <link>https://trid.trb.org/View/911379</link>
      <description><![CDATA[Currently, the use of global position system (GPS) for tracking and navigation purposes is considered a state-of-the-practice in vehicle location applications. For most applications, the general accuracies provided by a non-augmented GPS receiver is sufficient. However, for emerging transportation applications that require the determination of the lane of travel for a particular vehicle, higher tracking accuracies may be required. Such accuracy levels can be achieved with the use of GPS receivers augmented with differential correction. The purpose of this research is to conduct a preliminary analysis to compare GPS receivers without DGPS corrections to those supported by augmentation systems. Three GPS receiver setups were compared, one supported by the Wide Area Augmentation System (WAAS), one supported by the Canada-wide Differential GPS (CDGPS) service, and a third that did not incorporate any augmentation (i.e. a basic receiver). Based on field data collected in Vancouver, B.C., the results showed that, in terms of reliability, the performance of the three receiver setups were consistent and comparable, however with the CDGPS-augmented setup slightly outperforming the WAAS-augmented and non-augmented setups.  However, in terms of positional accuracies, identified by road lane differentiation, it was found that the differential-augmented receivers outperformed the non-augmented receiver. The results indicate that GPS receivers without augmentation systems are only suitable for applications that do not require highly accurate position information. There seem to be some potential in using differentially-corrected GPS receivers as complementary sensors for high-accuracy ITS applications such as VII/VIC, where need for high precision location information (i.e. lane of travel) is essential.]]></description>
      <pubDate>Tue, 16 Mar 2010 06:12:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/911379</guid>
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    <item>
      <title>Wide Area Augmentation System Research and Development</title>
      <link>https://trid.trb.org/View/898419</link>
      <description><![CDATA[In support of the development of the Wide Area Augmentation System (WAAS), three projects were performed under Aviation Cooperative Agreement 01-G-016. The first project involved participation in the WAAS Integrity Performance Panel (WIPP), which included the development of the dual-frequency Code Noise and MultiPath (CNMP) monitor, review of integrity documentation, as well as the analysis of specific integrity monitors. The second project was focused on the characterization and reduction of Geostationary Satellite (GEO) multipath error. The third project involved the development of a dual-frequency Integrated Multipath-Limiting Antenna (IMLA) for WAAS Reference Sites (WRS) to improve the accuracy of the pseudorange measurement data. Major findings of the research are summarized below: (1) A dual-frequency Code Noise and MultiPath (CNMP) monitor was developed to significantly reduce multipath error at the WAAS Reference Sites (WRS). (2) Based on ground and flight test evaluations, Narrow-Band Geostationary Satellite (GEO) multipath and noise ranging errors can be as small as 0.3 m (95%) if a multipath-limiting High-Zenith Antenna (HZA) is used. (3) A dual-frequency Integrated Multipath-Limiting Antenna (IMLA) was prototyped and determined to be feasible for WAAS applications. (4) A new method was developed for the measurement and evaluation of GPS antenna phase and group delays.]]></description>
      <pubDate>Wed, 12 Aug 2009 12:47:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/898419</guid>
    </item>
    <item>
      <title>Loran-C Augmentation for GPS and GPS/WAAS</title>
      <link>https://trid.trb.org/View/898342</link>
      <description><![CDATA[Illgen Simulation Technologies, Inc., (ISTI) participated in Loran-C and other navigational programs for the Federal Aviation Administration (FAA) and other governmental agencies for some fifteen years. The Cooperative Agreement reported here was carried out in support of the evaluation of the Loran-C navigational system as a partner for GPS systems in the National Airspace System (NAS), with recognition that other navigational and precise-timing applications exist. In December, 2003, ISTI was acquired by Northrop Grumman Corporation and was renamed Northrop Grumman Simulation Technologies Corp. (NGST). There were no personnel changes of significance to this cooperative agreement as a result of the acquisition. ISTI/NGST cooperated within a large and diverse team assembled by the FAA offering expertise in specific Loran-C-related areas. In 1997, ISTI personnel assisted the FAA in forming what is now the Loran-C Evaluation Program. Working with AND-740 at program inception and prior to initiation of Cooperative Agreement 99-G-038, hypotheses were formulated, and these are still pertinent today: Program Hypotheses Loran-C meets the requirements to support NAS operations including non-precision or LNAV/VNAV approach procedures. Loss of availability due to p-static no longer expected to be a significant factor Loran-C meets RNP 0.3 requirements accuracy, availability, integrity, continuity Advantages of a GPS/Loran-C combination are demonstrated in flight Availability of horizontal nav with integrity through approach if GPS is lost Ability to dispatch in the absence of onboard GPS capability CONUS and Alaska demonstrations show utility of Loran-C Coverage improvements for enroute navigation through NPA Augmentation of WAAS communication of GPS integrity Loran-C communication of Loran-C integrity, timing, control information Loran and Loran/GPS hybrids can be certified, and have NAS benefits RTCA, FAA documents, ops concepts.]]></description>
      <pubDate>Wed, 12 Aug 2009 12:46:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/898342</guid>
    </item>
    <item>
      <title>Single-Epoch Integer Ambiguity Resolution with GPS-GLONASS L1-L2 Data</title>
      <link>https://trid.trb.org/View/898384</link>
      <description><![CDATA[The effectiveness of single-epoch integer ambiguity resolution, which provides centimeter-level relative positioning in real-time, is a function of the number, quality and type of carrier phase measurements available. The authors apply the Local-Minima Search (LMS) method epoch-by-epoch to GPS-GLONASS dual frequency carrier phase measurements taken over 2, 9 and 18 km baselines. While the application of LMS to GPS dual frequency measurements alone works quite well over these baselines, the addition of GLONASS improves the search success rate and greatly enhances the ability to validate the resulting solutions. At both 9 km and 18 km the LMS success rate was nearly 100%, when using the combined set of carrier phases. The addition of GLONASS reduced the average search ratio by more than 1/3 over the ratio obtained using only GPS phases. A fuller GLONASS constellation will certainly improve on these results.]]></description>
      <pubDate>Wed, 12 Aug 2009 12:46:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/898384</guid>
    </item>
    <item>
      <title>WAAS IN CANADA : AUGMENTED GLOBAL POSITIONING SATELLITE SIGNALS PROMISE IMPROVED NAVIGATION IN CANADA</title>
      <link>https://trid.trb.org/View/748800</link>
      <description><![CDATA[NAV Canada and the Federal Aviation Administration (FAA) announced in September of 2004 that NAV Canada will host and maintain four ground monitoring stations, which will enable the airspace to have access to Wide Area Augmentation System (WAAS) signals, improved Global Positioning System (GPS) navigational devices and improved runway approach systems. WAAS offers positioning accuracy to within about two meters throughout a flight, its most publicized capability is on the approach, where positional accuracy is critical. Aircraft using GPS/WAAS signals will be able to be located vertically and laterally within two meter, with very high reliability. By contrast, GPS approaches rely on on-board equipment for vertical location and so are considered non-precision. The FAA calls this new level of service, "lateral precision, vertical guidance" (LPV). It is also close to the CAT-1 minimums for approaches. WAAS approaches can be tailored to any runway, but justification needs to be made for the design of one. Increased usability is a generally accepted benchmark. Future developments in WAAS depend on how and if the system is supported by additional operators, including the International Air Transport Association. Supporters expect it to eventually catch on, just as GPS supported approaches did starting in 1994.]]></description>
      <pubDate>Wed, 02 Feb 2005 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/748800</guid>
    </item>
    <item>
      <title>NATIONAL AIRSPACE SYSTEM: PERSISTENT PROBLEMS IN FAA'S NEW NAVIGATION SYSTEM HIGHLIGHT NEED FOR PERIODIC REEVALUATION</title>
      <link>https://trid.trb.org/View/654849</link>
      <description><![CDATA[In light of the expected costs of the Federal Aviation's (FAA's) new navigation system and continuing concerns about the Wide Area Augmentation System's (WAAS's) ability to achieve cost, schedule, and performance goals (FAA requires that its navigation system be unavailable no more than 5 minutes per year for some types of navigation and landing), the General Accounting Office (GAO) was asked to provide information on whether (1) the Department of Defense's current Global Positioning System (GPS) or its planned improvements for GPS can meet FAA's navigation requirements, (2) the benefits of FAA's chosen approach to an augmented system currently outweigh the cost of this system, and (3) other technologies are available to meet FAA's requirements and users' needs for a new navigation system.  Briefly, the current GPS does not meet all of FAA's civil aviation navigation requirements for accuracy, integrity, and availability.  GPS does not provide the assurance that its signal will be available virtually all of the time.  FAA's 1999 analysis concluded that the quantified benefits of its approach would outweigh the cost.  Since completing this analysis, FAA has experienced delays and cost increases primarily because of difficulties in meeting its integrity requirement.  As a result, it is unclear whether quantified benefits will still outweigh costs.  At the present time, no other navigation technologies - including variations of ground-based and less robust satellite-based systems - are available to meet FAA's requirements and users' needs for precise landing guidance at more airports.]]></description>
      <pubDate>Thu, 03 Aug 2000 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/654849</guid>
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    <item>
      <title>NATIONAL AIRSPACE SYSTEM: OBSERVATIONS ON THE WIDE AREA AUGMENTATION SYSTEM. TESTIMONY</title>
      <link>https://trid.trb.org/View/496532</link>
      <description><![CDATA[This is the statement of Gerald L. Dillingham, Associate Director, Transportation Issues, Resources, Community, and Economic Development Division before the Subcommittee on Aviation, Committee on Transportation and Infrastructure, House of Representatives.  FAA is acquiring the Wide Area Augmentation System (WAAS) - a network of equipment on the ground and in space - to enhance DOD's Global Positioning System (GPS) so that the system can meet civil aviation requirements; specifically, so that the system can be available virtually all of the time. Satellite based navigation, using GPS/WAAS, is expected to improve the safety of flight operations, allow the fuel-efficient routing of aircraft, increase airport and airspace capacity to meet future air traffic demands, and enable FAA to phase out its costly network of ground-based navigation aids.  The purpose of this testimony is to aid congressional oversight by providing insights into the cost, schedule, and technical issues that have drawn considerable attention to the WAAS program.  The testimony discusses: (1) the likelihood of WAAS' satisfying key performance requirements within current program cost and schedule estimates; (2) the importance of avoiding delays in FAA's timetable for shutting down (decommissioning) ground-based navigation aids; and (3) the potential impact of cost increases and decommissioning delays on the benefit-cost analysis for the WAAS program.]]></description>
      <pubDate>Fri, 12 Mar 1999 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/496532</guid>
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