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5 CHAPTER 2 Literature Review A guard/restraining rail practice survey was conducted ature published on these topics. The following comments are during the Phase I study (1) and during TCRP Project D-07/ based on the results of the literature review. Task 8 published as TCRP Report 71, Volume 5: Flange Climb One of the main functions of a guard rail is to prevent flange Derailment Criteria and Wheel/Rail Profile Management and climb derailment. Most flange climb derailments occur under Maintenance Guidelines for Transit Operations (2). Radii of the following conditions: curves on which transit systems install guard rails differ Tight curves or small radius switches, mostly in yards; from 500 to 1,000 ft. The flangeway clearance differs from Low flange angle wheels; 1.5 to 2.5 in. depending on the wheelset and track geometry High W/R friction coefficient, such as a new trued wheel dimensions. Most of the track standards used on various with a rough surface; transit properties are based simply on prior practice without Independent rotating wheels (IRW); and independent verification that the practice is still appropriate Severe track perturbations. or effective. The Phase I study proposed optimization methodologies for Table 1 shows that the wheel flange angle used in different guard rail installation based on the "sharing contact" philos- transit systems ranges from 63 to 77 (3). The effect of the flange ophy (Philosophy I), which need to be justified. This study angle and the other factors listed above, including vehicle conducted an additional literature review that focused on the suspensions and the operation environment, on flange climb guard rail installation criteria or standards worldwide and the derailment needs to be investigated in order to create guard/ philosophies behind them. However, there is very little liter- restraining rail guidelines. Table 1. Wheel flange angle. Wheel Flange Angle Transit System* 63 BART (Transit Rail Car), Toronto, SEPTA, WMATA (Transit Rail Car) Santa Clara VTA, Portland MAX, Edmonton, Houston, Baltimore, Dallas, 70 KOLN, SEPTA (Transit Rail Car) 75 MBTA, NJT HBL and Newark, San Diego, Pittsburgh 77 BOCHUM, ZURICH * The vehicles in this table are Light Rail Vehicles (3), except for those specified as Transit Rail Car.