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Web-Only Document 9: Scoping Airport Cooperative Research Program J. Page K. R. Bassarab C. M. Hobbs D. H. Robinson T. D. Schultz B. H. Sharp S. M. Usdrowski Wyle Laboratories, Inc. Arlington, VA And P. Lucic CSSI, Inc. Washington, DC Contractorâs Final Report for ACRP Project 11-02 Task 8 Submitted June 2009 ACRP Volume 1 Enhanced Modeling of Aircraft Taxiway Noise
ACKNOWLEDGMENT This work was sponsored by the Federal Aviation Administration (FAA) in cooperation with the Airport Cooperative Research Program (ACRP) Oversight Committee (AOC). It was conducted through ACRP, which is administered by the Transportation Research Board (TRB) of the National Academies. COPYRIGHT PERMISSION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, Transit Development Corporation, or AOC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for- profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinions and conclusions expressed or implied in the report are those of the research agency. They are not necessarily those of the TRB, the National Research Council, the FAA, the AOC, or the U.S. Government. This material has not been edited by TRB.
iv CONTENTS ACKNOWLEDGMENTS ......................................................................................................... viii ABSTRACT .................................................................................................................................. ix EXECUTIVE SUMMARY ...........................................................................................................x CHAPTER 1 Introduction ...........................................................................................................1 CHAPTER 2 Airport Taxiing Operations ..................................................................................3 2.1. FAA ATC Rules and Regulations Affecting Taxi Operations ....................................3 2.2. Holding Queues ...........................................................................................................5 2.2.1. Total Airspace and Airport Modeler (TAAM®) ..............................................6 2.2.2. EDMS and the WWLMINET Queuing Module ...............................................7 2.3. Typical Taxi Behavior: Ground Speed, Engine Use and Thrust .................................8 2.4. Accelerating Aircraft and Breakaway Thrust ............................................................12 2.5. CAEP Alternative Emissions Methodology ..............................................................18 2.6. Relative Contributions of Ground Operations and Flight Noise ...............................20 2.7. Environmental Factors: Terrain, Buildings, Ground Cover.......................................22 CHAPTER 3 Measured Aircraft Taxiing Source Noise Characteristics ...............................28 3.1. Taxi / Idle Condition Measurement Data Sources .....................................................28 3.1.1. T. F. Green State Airport (PVD) Taxi Measurement Data .............................28 3.1.2. Milwaukee Airport (MKE) Static Run up Noise Measurement Data .............28 3.1.3. Ronald Reagan Washington National (DCA) Taxi Measurement Data .........29 3.1.4. Static Engine Idle Data ...................................................................................31 3.1.5. Madrid Taxi Measurement Data .....................................................................32 3.1.6 IAD Directivity and Breakaway Thrust Measurement Data ............................33 3.2. Source Directivity ......................................................................................................33 3.2.1. Lateral Directivity ...........................................................................................33 3.2.2. Longitudinal Directivity..................................................................................37 3.3. Source Spectra ...........................................................................................................39 3.3.1. Taxiing Noise Levels and Spectra ..................................................................39 3.3.2. The Impact of Spectral Class Selection ..........................................................41 3.4. Source Noise Sensitivity at Low Power Settings .......................................................42 3.5. Combining Spectra and Directivity into a Noise Sphere ...........................................44 CHAPTER 4 Operational Modeling .........................................................................................45 4.1. Single Event Analysis ................................................................................................45 4.1.1. Source Modeling (simulation comparisons using various fidelity spheres) .................................................................................45 4.2. Multiple Operations ...................................................................................................50 4.2.1. Operational Modeling using INM7 .................................................................50
v 4.2.2. Geometric Modeling Fidelity ..........................................................................51 4.3. INM Modeling Considerations ..................................................................................59 4.3.1. Duration and Noise Exposure from Static Run up Operations .......................59 4.3.2. Selection of NPD curves for a Moving Taxi Operation .................................60 4.3.3. Combining Static and Moving Portions of Taxi Operations ..........................61 4.3.4. Comparison of INM7 Extrapolated NPD data with Taxi Measurement Data .................................................................................63 4.3.5. Specifying NPD Curves ..................................................................................66 4.3.6. Source Height Modeling and INM Directivity ...............................................68 4.3.7. Effects of Taxi Speed ......................................................................................70 4.3.8. Single Event Standard INM7 Modeling of Time in Mode Operations ...........71 CHAPTER 5 Suggestions ...........................................................................................................73 5.1. Source and Propagation Modeling .............................................................................73 5.1.1. INM NPD Data ...............................................................................................73 5.1.2. Thrust Settings for Taxi Operations ................................................................73 5.1.3. Lateral and Longitudinal Directivity ..............................................................73 5.2. Trajectory / Airspace Modeling .................................................................................74 5.2.1. Terminal & Gate Modeling .............................................................................74 5.2.2. Static Operations, Holding Queues and Breakaway Thrust Modeling ...........74 5.2.3. Moving Aircraft along Constant Speed Segments ..........................................74 5.2.4. Simplified Time in Mode Modeling ...............................................................74 5.3. Taxi Noise Modeling Implications on INM Data Requirements ...............................75 5.3.1. NPD Data ........................................................................................................75 5.3.2. Spectral Classes ..............................................................................................75 5.3.3. Directivity Considerations ..............................................................................75 5.3.4. Aircraft Performance / Operational Thrust Data ............................................76 CHAPTER 6 INM Taxi Noise Implementation .......................................................................77 6.1. Taxi Operations ..........................................................................................................77 6.1.1. Taxi Tracks .....................................................................................................77 6.1.2. Taxi Profiles ....................................................................................................78 6.1.3. Thrust Settings for Taxi Operations ................................................................79 6.2. Acoustic Algorithms ..................................................................................................80 6.2.1. Source Spectra ................................................................................................80 6.2.2. Taxi-NPD Data ...............................................................................................81 6.2.3. Taxi Longitudinal Ground-Based Directivity .................................................82 6.2.4. Ground-Based Directivity Smoothing at Larger Distances ............................84 6.2.5. Engine Installation Effects (Lateral Directivity) .............................................84 6.2.6. Noise Fraction Adjustment for Taxi Segments ...............................................85 CHAPTER 7 AEDT Implementation Concept ........................................................................86 7.1. EDMS Description .............................................................................................86
vi 7.2. Airport Description ....................................................................................................86 7.2.1. Taxi Tracks .....................................................................................................87 7.2.2. Taxi Profiles ....................................................................................................87 7.2.3. Gates ...............................................................................................................87 7.2.4. Terminal Area .................................................................................................89 7.2.5. Taxi Speed ......................................................................................................89 7.2.6. Buildings .........................................................................................................90 7.3. Operations ..................................................................................................................90 7.3.1. Times in Mode ................................................................................................90 7.3.2. Taxi Time Modeling .......................................................................................91 7.3.3. Aircraft Schedule Options...............................................................................91 7.4. Acoustic Computation ...............................................................................................92 7.5. Thrust-Noise Sensitivity ............................................................................................92 CHAPTER 8 The Path Forward ...............................................................................................93 REFERENCES .............................................................................................................................95 APPENDIX A Reagan Washington National Airport (DCA) Taxi Noise Measurements . A-1 A.1. DCA Taxi Noise Measurement Setup .................................................................... A-1 A.2. DCA Taxi Noise Field Measurements ................................................................... A-4 A.3. DCA Measurement Analysis ................................................................................. A-9 APPENDIX B T. F. Green Airport (PVD) Taxi Noise Measurements ................................B-1 B.1. T.F. Green State Airport Tax Noise Measurement Setup .......................................B-1 B.2. T.F. Green Taxi Noise Field Measurements ...........................................................B-2 B.3. T.F. Green Taxi Noise Measurement Analysis .......................................................B-4 APPENDIX C Washington Dulles International Airport Breakaway Thrust Noise Measurements ................................................................................ C-1 C.1. Measurement Description .......................................................................................C-1 C.2. Analysis ...................................................................................................................C-5 C.2.1. Airbus A320-232 ..........................................................................................C-5 C.2.2. Boeing B757-222 .........................................................................................C-7 C.3. Conclusions .............................................................................................................C-8 APPENDIX D EDMS Modeling of Airside Operations ....................................................... D-1 D.1. Introduction ............................................................................................................ D-1 D.2. Emissions Inventory ............................................................................................... D-1 D.3. Dispersion Modeling .............................................................................................. D-3 D.4. Delay and Sequence Modeling .............................................................................. D-5 D.5. Airport (Airside) Delay Model .............................................................................. D-6 D.6. Equipment Modeling.............................................................................................. D-7 D.7. Modeling of Taxi Paths .......................................................................................... D-7 D.8. References .............................................................................................................. D-9
vii APPENDIX E Algorithms Employed in the Processing of the European FDR Data .........E-1 E.1. Flight Segment Parsing............................................................................................ E-1 E.2. Description of the Taxi Hold Processor .................................................................. E-2 E.3. Acceleration after a Hold Event .............................................................................. E-3 E.4. Thrust during Acceleration after a Hold Event ....................................................... E-5
viii AKNOWLEDGMENTS The research reported herein was performed under ACRP Project 11-02 / Task 08, FY2008 by Wyle Laboratories, Inc., in Arlington, Virginia. Wyle Laboratories is the prime contractor for this study, with Panta Lucic, of CSSI, Inc. as a project consultant and contributor. The authors would like to express our sincere gratitude to Neal Phillips and Mike Jeck of the Metropolitan Washington Airports Authority for coordinating escorted access to Washington Reagan and Dulles International Airfields enabling us to conduct acoustic measurements of taxiing operations. Some of the engine data cited in this report was graciously provided by Larry Bock of Pratt and Whitney. Our sincere thanks go to Chris Roof and George Noel at the U.S. D.O.T. Volpe Center for providing the labor and resources to access their databases with flight data recorder information from which many pertinent taxiing parameters were obtained. And last but certainly not least, the Principal Investigator expresses gratitude to her Wyle colleagues for their incredible work and dedication on this challenging project.
ix ABSTRACT Aircraft taxi noise acoustic sensitivity studies were conducted to document the importance of the modeling elements within INM and AEDT: source noise, operations, and environmental propagation. Sensitivity studies decoupled the taxi noise into the three areas and exercised each element independently. Limited opportunistic commercial aircraft taxi operation acoustic measurements were conducted. Independent taxi flight data recorder (FDR) information was queried to determine statistical engine and aircraft operational parameters. The sensitivity studies revealed the primary driver for prediction is source noise: level, spectra and directivity. A nominal taxi state NPD, spectral class and directivity database is suggested based on existing data augmented with measurements. There is sufficient capability in INM to support detailed taxi operations. Future improvements planned for AEDT will reduce user input burden. The propagation algorithms, primarily lateral attenuation are sufficient. Airport-specific considerations may necessitate inclusion of terrain, shielding and variable ground impedance. The measured acoustic data and FDR data were separate; therefore one could not quantify sensitivity of taxi noise to thrust. This identifies a need for a concurrent acoustic/FDR dataset. The study suggests modeling nominal taxi state in the short term with a comprehensive long term enhanced acoustic sensitivity to thrust capability.
x EXECUTIVE SUMMARY Introduction The objective of this scoping project was to determine the best way to model airport noise from aircraft taxi operations and to create a plan for implementation of a taxi noise prediction capability into INM in the short term and AEDT in the longer term. A comprehensive series of acoustic sensitivity studies were conducted in order to develop a physical understanding and draw conclusions about the relative importance of the various modeling elements (source, environment, operations) within the framework of INM and AEDT. The sensitivity studies were based upon decoupling the modeling of taxi noise into the following three areas and exercising each element independently. 1. Engine source noise (level, spectra, directivity); 2. Aircraft movements and operating states (location, duration, power setting); and 3. Environment / propagation (lateral attenuation, terrain, shielding, and ground impedance). Findings The sensitivity studies revealed that the primary weakness for taxi noise modeling is related to item #1, engine source noise modeling. A nominal taxi state noise NPD, spectral class and directivity database can be developed using existing data and augmented with additional acoustic measurement data. The existing source directivity model in INM needs to be modified to more appropriately account for taxi operations. At present there is sufficient capability in INM to support item #2 via detailed aircraft taxi movements, from gate to runway, terminal to runway or via time in mode assignments. Future aircraft movement and queuing modeling improvements targeted for AEDT will greatly reduce the current user input burden in INM. It was found that for #3, the propagation algorithm (primarily lateral attenuation in INM), is sufficient and only site-specific airport considerations will necessitate the inclusion of terrain, shielding and / or variable ground impedance. Therefore no recommendation to always or never include such effects could be made. Conclusions During the course of the project, opportunistic noise measurements were conducted in order to obtain acoustic data from commercial aircraft during taxi operations for a limited number of aircraft events. Additionally, existing flight data recorder (FDR) information was queried to determine statistical information about aircraft taxi operating parameters and typical taxi operational patterns. The acoustic data and FDR data were not gathered concurrently; therefore one could not definitively determine the noise level for a particular taxi engine thrust, or the sensitivity of noise with changes in thrust. The need for concurrent acoustic and engine operating state data is an important finding of this study and is the primary reason for considering only a nominal taxi state in the short term, and the recommendation of a comprehensive long term solution seeking concurrent taxi noise and operating condition measurements for the purposes of developing an enhanced acoustic sensitivity to thrust capability for AEDT.
xi Suggestions While the scoping study suggestions are applicable to both INM and AEDT, we found that taxi noise can result in a âsignificant impactâ (DNL increase of more than 1.5 dB) under certain conditions, and hence suggest short term implementation in INM, so that an improved taxi modeling capability may be provided to the noise modeling community sooner rather than later. The projected rough order of magnitude costs for implementing a taxi noise capability in INM alone is $220k, in INM + AEDT is $310k and in AEDT only is $240k. Included in these estimates is the approximate $130k cost for development of the various aircraft and acoustic taxi databases. This report documents both the acoustic sensitivity studies and a technical implementation plan for a comprehensive taxi noise computational capability in INM/AEDT.
