Performance Based Track Geometry Phase 2 (2015) / Chapter Skim
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C H A P T E R 2 Research Approach 2.1 Vehicle Characterization and Ride Quality Testing TTCI partnered with PATH to participate in this research. PATH supported the project by providing a test vehicle for TTCI to perform characterization and ride quality tests.
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Figure 1. PATH Rail System Map PATH's PA5 passenger car (with all axles powered)
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Table 1. PATH Design Specifications PATH Railcar Design Specifications Weight Load Condition : AWO 72,450 pounds Load Condition : AW3 95,330 pounds Primary Suspension System Chevron Secondary Suspension System Airbag Wheel Profile PATH Design Cylindrical Wheel TTCI has often found that actual vehicle characteristics as assembled may vary considerably from the published design and measured individual components.
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Location Number Description 1 Vertical and Lateral Accelerometer 2 Vertical and Lateral Accelerometer 3 Vertical and Lateral Accelerometer 4 Lateral Accelerometer (top) 5 Vertical Accelerometer The following equations are used to determine carbody resonance for measured accelerations: Bounce 𝑎𝑎1𝑣𝑣+𝑎𝑎2𝑣𝑣 2 +𝑎𝑎5𝑣𝑣 2 Pitch 𝑎𝑎1𝑣𝑣+𝑎𝑎2𝑣𝑣 2 − 𝑎𝑎5𝑣𝑣 Yaw 𝑎𝑎1𝑙𝑙+𝑎𝑎2𝑙𝑙 2 − 𝑎𝑎3𝑙𝑙 Roll 𝑎𝑎4𝑙𝑙 − 𝑎𝑎1𝑙𝑙+𝑎𝑎2𝑙𝑙+𝑎𝑎3𝑙𝑙 3 Figure 4.
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Figure 5. Example of Carbody Resonance Data Table 2.
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placed across both the primary and secondary suspension systems to measure the displacement resulting from the applied load. Figures 6 and 7 show the test setup.
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Figure 8. Example of Longitudinal Stiffness Test Data Table 3.
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Figure 9. Lateral Stiffness Test Setup Force-displacement slopes were calculated for each run.
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effective vertical and shear stiffness are nonlinear. The donut spring is a safety spring that will support the load of the car if the airbag system deflates.
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Table 5. Secondary Suspension Vertical Stiffness Suspension Component Average Measured Value Total Air spring System Stiffness 3,066 lb/in Donut Spring Stiffness 18,351 lb/in Airbag Stiffness 8,525 lb/in Reservoir Stiffness 6,539 lb/in Primary Suspension System The primary suspension system consists of a pair of chevrons.
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Table 6. Primary Suspension Stiffness Suspension Component Manufacturer Value Average Measured Value Difference Primary Suspension Stiffness per axle box (pair of chevrons)
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Table 7. Ride Quality Test Accelerometer Locations Description Type of Measurements Notes 1 Axle Acceleration Longitudinal, Lateral, Vertical 2 Axle Acceleration Longitudinal, Lateral, Vertical 3 Axle Acceleration Longitudinal, Lateral, Vertical 4 Axle Acceleration Longitudinal, Lateral, Vertical 5 Driver's Cab Acceleration Longitudinal, Lateral, Vertical Accelerometer placed on floor under driver's seat.
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Figure 14. Axle Box Accelerometer Figure 15.
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Figure 17. Carbody Accelerometer in Driver's Cab Figure 18.
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2.3.1 ISO 2631 Ride Quality Analysis Requirements The well recognized and widely used ISO 2631 standard was used for analysis of the passenger ride quality.5 The standard defines methods for quantifying whole body vibration and effects on human health and comfort, probability of vibration perception, and incidence of motion sickness. The following types of vibrations are covered in this standard: • Periodic vibration is oscillatory motion whose amplitude pattern repeats after fixed increments of time.
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Figure 19. Consist Setup The acceleration data in the driver's cab was analyzed in accordance with ISO 2631.
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Figure 21. VDV Ride Quality calculated for 33rd Street to Journal Square Figures 22 and 23 show the measured accelerations, speed, and track geometry between the stations.
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Figure 22. Vertical Accelerations compared to Track Geometry -40 -30 -20 -10 0 10 20 30 40 -5.00 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 5.00 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Cu rv at ur e ( de g)
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Figure 23. Lateral Accelerations compared to Track Geometry 0 5 10 15 20 25 30 35 40 -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Sp ee d ( mp h)
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Figure 24. Lateral Frequency Content Figure 25.
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2.3.3 Newark to World Trade Center Figure 26 describes the location of test car 5746 in the train consist. The A-end of the car was leading from Newark to World Trade Center, and the B-end was leading in the other direction.
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Figure 28. VDV Ride Quality calculated World Trade Center to Newark Figures 29 and 30 show the measured accelerations, speed, and track geometry between the stations.
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Figure 29. Vertical Accelerations compared to Track Geometry 27
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Figure 30. Lateral Accelerations compared to Track Geometry 28
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Figure 31. Lateral Frequency Response Figure 32.
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