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53 8.0 CONCLUSIONS 8.1 Ride Quality Standard Literature Review All the ride quality standards reviewed in this study require similar measurements. TTCI identified the following measurements to be made in order to quantify the relationship between track geometry and ride quality: 1. Tri-axial accelerometers located a. Over bogie centers (both ends of vehicle) b. Center of vehicle c. Floor in operatorâs cabin 2. Lateral accelerometers located a. Each axle of bogie so yaw can be calculated and location of curve accurately pinpointed 3. Roll rate gyrometer Based on the literature review, TTCI recommended that ride quality during the tests be calculated using ISO 2631, which was reviewed in the literature survey. The data was filtered post-process for ISO 2631. 8.2 Vehicle Characterization Testing TTCI has often found that actual vehicle characteristics as assembled vary considerably from the published design and measured individual components. In order to ensure an accurate NUCARS model of the DART SLRV, tests were conducted to measure suspension characteristics and carbody inertial and resonance characteristics. All testing was performed on DART property located in Dallas, Texas. DARTâs operating conditions provided a variety of track structures and a wide range of operating speeds. DARTâs SLRV was used for testing. The SLRV is a three-section vehicle that can accommodate up to 150 seated and standing passengers. Testing included the following: ⢠Characterization of the elastic elements of the primary and secondary suspension ⢠Determination of the center of gravity of the railcar ⢠Determination of the resonance frequencies of rigid body degrees of freedom of the railcar The measured values for some of the suspension characteristics varied from the manufacturerâs specifications; e.g., manufacturer specifications were given for a single component, but when the component is part of a suspension system, the effective stiffness may vary. All of the measured values were used to update the NUCARS model to represent the test vehicle as accurately as possible. 8.3 Track Geometry Measurements Track geometry measurements were taken by Holland on August 13-14, 2010 on DART Red Line for southbound and northbound track. No measurements were taken in the DART tunnel (between Pearl and Cityplace) because of a size restriction in the tunnel.
