Performance-Based Track Geometry, Phase 1 (2012) / Chapter Skim
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56 APPENDIX RIDE QUALITY LITERATURE REVIEW TCRP D-7 Track Geometry and Ride Quality Research By C.D. Ketchum, Transportation Technology Center, Inc.
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57 A1.0 INTRODUCTION Typical track geometry design and maintenance standards address acceptable geometric restraints based on past safety acceptance levels, but disregard overall performance of various vehicle types and acceptable passenger ride quality standards. In support of the Transit Cooperative Research Program D-7 research program, TTCI is investigating the effect of current track design, geometry, and maintenance standards that will account for vehicle performance and passenger ride quality using a combination of PBTG and NUCARS®9 In Phase I of this work, TTCI has conducted a literature survey to identify how transit authorities around the world measure and assess passenger ride quality and passenger ride comfort.
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58 • Comfort disturbances due to motions such as high horizontal acceleration, jerks, and jolts. These disturbances can be due to discrete events that may have both high- and low-frequency content.
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59 Table A1. Passenger/Vehicle Interfaces Position Interface Standing • Floor/feet Seated • Seat-supporting surface • Seat back • Floor/feet Recumbent • Surface supporting the pelvis, back, and head Figure A1.
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60 quality. Different frequency weightings are used for different axes of vibration.
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61 Figure A3. Lateral Exposure Criteria Curves showing Reduced Comfort Boundaries Table A2 shows how the weighted accelerations are related back to passenger comfort perception.
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62 and crew are exposed in railway vehicles5 Vibration accelerations can be characterized by translational and rotational components. However, in this standard it was assumed that for rotational vibration the center of rotation is large enough to consider the vibration as translational.
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63 Structural arrangements (steel, aluminium, type of suspension, type of bogie, wheel profile) ─ Description of seat Type (single, multiple, etc.)
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64 Table A4. ENV 12299:1999 Railway Applications Description Included Excluded Effect of vibration • Comfort • Health • Activities Transmission • Whole body through passenger interface • Single body part • Whole Surface • Vehicle Motion Type of vehicle • Railway vehicles designed for carrying passengers • Other types of railway vehicle (e.g.
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65 Figure A4. Frequency Weighting Curve for Weighting Factor Wab and Wad Several analysis methods are provided for measured accelerations.
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66 • Complete Mean Comfort Method is based on measurements at the floor and seat interface. This method correlates better to passenger perception and is recommended to be used where practical.
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67 obtained over 5-minute periods, between the accelerations measured in the vehicle and the average of the vibration comfort ratings given by a representative group of passengers. The evaluation methods in this standard are based on the following: • Low level vibration • Large part of energy contained below 3 Hz • Physiological weightings have been made in particular in the frequency range of 0.5 to 5 Hz.
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68 A3.3.2 Report Format The following information should be reported according to UIC 513: • Subject of the test • Method of evaluation ─ Simplified ─ Full • Test conditions • Description of vehicle ─ Type of vehicle (motor car, passenger coach, locomotive, etc.) ─ Vehicle loading conditions ─ Structural details (steel, aluminium, type of suspension, etc.)
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69 • Ride comfort 10/1 3 )
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70 Figure A5. Sperling Frequency Weighting Curves -30 -25 -20 -15 -10 -5 0 5 0.01 0.1 1 10 100 1000 G ai n (d B )
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71 A4.0 STANDARD COMPARISIONS Table 9 summarizes the standards reviewed in this literature review. Table A9.
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72 A5.0 STANDARDS AND PASSENGER PERCEPTION Many passengers who commute on trains use the time read, write, or work on laptop computers. The rail vehicle, in many cases, becomes an extension of a person's office.
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73 It may be necessary to look at discrete events individually to determine effects on ride quality. Some of the discrete events that may cause lateral vibration, jerk, and vertical vibrations are transition curves, turnouts, and corrugations to name a few.
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74 2. Primary suspension is unchanged from base model and secondary suspension is modeled by a nonlinear rubber element 3.
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75 Figure A7. Track Geometry Deviations and Roughness Levels Figure A8 shows the calculated ride comfort for different track roughness levels shown in Figure A7.
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76 Figure A9 shows comfort index related to ballast stiffness. Bξ is the ratio between the actual ballast stiffness and the change in stiffness.
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77 Results of the study showed that ride comfort can be affected significantly by track roughness. Speed also has an effect on ride comfort.
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78 events being averaged with the rest of the route. It may be necessary to analyze discrete events independently to get a more accurate picture of ride quality.
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79 5. International Organization for Standardization (ISO)
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80 17. Price, Brian L., Mary Claire Froelich, Eric Pierce, Jeffrey Blankenship, Joseph LaBrecque, and Michael McCauley.
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81 30. Esveld, Coenraad.
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82 45. Kufver, Björn.
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83 ACOUSTICS High Tatras 2009 34th 59. Popprath, S., C
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84 Appendix AA – International Standard for Organization ISO 2631 The detail for the analysis methods included in ISO 2631 are given in this appendix.
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85 T is the duration of measurement Note: When the vibration exposure consists of two or more periods of different magnitudes, the vibration dose value for the total exposure should be calculated from the fourth root of the sum of the fourth power of individual dose values: ∑= i itotal VDVVDV 4 1 4 )
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86 AA7. Multiplying Factors Table AA2.
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87 APPENDIX AB – EUROPEAN STANDARD ENV 12299:1999 The detail for the analysis methods included in European Standard ENV 12299:1999 are given in this appendix.
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88 This index is based on the relationship between the relevant magnitudes of lateral jerk, body roll speed, variation of lateral acceleration level, and the average value of the comfort information given. Comfort Index on Curve Transitions E CT DCyByAP ϑ *
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89 APPENDIX AC – UIC 513 The detail for the analysis methods included in UIC 513 are given in this appendix.
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