Performance-Based Track Geometry, Phase 1 (2012)

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4 1.4 PBTG PBTG inspection is a new technology that can be implemented on conventional track geometry inspection vehicles. This technology relates measured track geometry to vehicle performance on a real-time basis. The technology can also be used on historic track geometry data in an office environment to post-process the data to evaluate the effect of track geometry deviations on vehicle performance. The PBTG inspection technology was developed by TTCI under the Association of American Railroads’ Strategic Research Initiatives Program. The technology has been demonstrated successfully on the test tracks at the Transportation Technology Center, as well as in revenue service. The BNSF Railway and the Union Pacific Railroad have implemented this technology on their track geometry inspection cars. PBTG inspection is an improvement over the traditional track geometry inspection method. Track geometry defects identified using traditional methods do not always cause undesirable vehicle performance. TTCI’s PBTG inspection technology identifies track segments that may produce undesirable vehicle performance and generates recommended track geometry maintenance actions on a real-time or on a post-processed basis. Implementation of this technology allows transit authorities to prioritize track maintenance based upon vehicle performance. As such, transit authorities can expect to reduce the potential for derailment incidents and improve vehicle ride quality by improving vehicle/track interaction. 2.0 LITERATURE SURVEY There are many ride quality standards available to evaluate passenger comfort on trains. The following four standards were reviewed: 1. ISO 2631 Mechanical Vibration and Shock — Evaluation of human exposure to whole-body vibration 2. ENV 12299:1999 Railway Applications — Ride comfort for passengers – Measurement and Evaluation 3. UIC 513 — Guidelines for evaluating passenger comfort in relation to vibration in railway vehicles 4. Sperling Index Table 2 summarizes the ride quality standards that were reviewed.

5 Table 2. Ride Quality Standards Comparison Standard ISO 2631 ENV 12299 UIC 513 Sperling Index Effect of movement • Health (0.5 to 80 Hz) • Comfort/Perception (0.5 to 80 Hz) • Motion Sickness • Health (0.5 to 80 Hz) • Comfort/Perception (0.5 to 80 Hz) • Motion Sickness • Health (0.5 to 80 Hz) • Comfort/Perception (0.5 to 80 Hz) • Motion Sickness • Health (0.5 to 80 Hz) • Comfort/Perception (0.5 to 80 Hz) • Motion Sickness Transmission • Whole body through interfaces • Whole body through interfaces • Whole body through interfaces • Whole body through interfaces Position of passenger • Standing • Seated • Recumbent • Standing • Seated • Standing • Seated Type of vehicle • ISO 10056 – Railway vehicles • Railway vehicle designed for carrying passengers • Railway vehicle designed for carrying passengers Measurement type • Translational • Translational • Rotational • Translational Analysis methods • Basic Method • Running RMS (root- mean-square) method • Fourth Power Vibration Dose Method • Simplified Mean Comfort • Complete Mean Comfort • Comfort on Discrete Events • Comfort in Curves • Simplified Method • Full Method Persons Not applicable Not applicable Two persons • 114.54 lb (52kg) • 198.42 lb (90kg) The literature survey determined what measurements and analysis method should be used to accurately correlate ride quality to track geometry. The data collected will eventually be used to help develop a PBTG method to predict the effects of track geometry on ride quality. Not all issues that can affect passenger ride quality were addressed by the standards reviewed. Discrete events were also important in correlating track geometry to ride quality. All the ride quality standards reviewed in this study required similar measurements. TTCI identified the following measurements needed 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 operator’s cabin 2. Lateral accelerometers located a. Each axle of bogie to calculate yaw and accurately pinpoint location of curves 3. Roll rate gyrometer located a. Under operator’s seat Based on the literature review, TTCI recommended that ride quality during the tests be calculated using ISO 2631. The data was filtered post-process for ISO 2631.