ASME RT-1-2020 pdf download

ASME RT-1-2020 pdf download.Safety Standard for Structural Requirements for Light Rail Vehicles and Streetcars.
3.2 LRV and Streetcar Leading End Design for Protection of Street VehicLes
For light rail vehicles and streetcars operating in urban environments sharing roadways and crossings, the design of the leading end of the vehicle shall incorporate a contoured geometry shape extending across the width of the vehicle, enclosing open area spaces to encourage deflection of struck objects from the path of the LRV/ streetcar and to minimize entrapment, override, and penetration of automobiles and light trucks. Sharp corners and protruding shapes of the contoured geometry design shall be minimized. A bumper, coupler enclosure, pilot beam, skirting, and/or alternative structures may be used to achieve these objectives.
The bottom of the car end structures as described in para. 3.1, with nominal floor height conditions, shall not be greater than the larger of 250 mm (10 in.) above the top of rail or the minimum allowable by the dynamic operating envelope.
The leading end design shall take into account collision compatibility with automotive construction.
NOTE: Side structures for typical automobiles and light trucks are designed for load-bearing reinforcement at a height above the roadway surface ranging from 250 mm to 635 mm (10 in. to 25 in.). Matching the leading end geometry and structural design of the LRV/streetcar to this height reduces the likelihood of LRV/ streetcar penetration into passenger compartments of these vehicles, thus reducing injury propensity. See SAE Paper No. 1999-01-0071 (section 11).
4 STRUCTURAL REQUIREMENTS
The carbody shall withstand the maximum loads consistent with the operational requirements and achieve the required service life under normal operating conditions. The carbody and vehicle design shall be based on the design load requirements specified in section 5. The capability of the structure to meet these requirements shall be demonstrated by calculation and/or appropriate proof-of-design testing. The vehicle is assumed to be of double-end design with an operating cab at either end. If the vehicle is of single-end design, the rear of the vehicle should be of equivalent design, and in a collision, should respond in the same manner as the front end.
The strength of connections between structural members for all structural loading requirements outlined in Tables 4-1 and 4-2 shall exceed the ultimate load- carrying capacity of the weakest member joined. For these load cases, the ultimate load-carrying capacity is defined by applying the load at the location and in the direction specified in Tables 4-1 and 4-2 but increased in magnitude to the maximum load that can be resisted by the structure, as determined by observing that further increase in deflection will result in a decrease in the load capable of being carried by the structure.
(b) The crashworthiness performance is specified by the following collision scenarios and acceptable outcomes:
(1) Scenario 1 (Low-Speed Collision). This is a relatively low-severity frontal collision between two LRVs or two streetcars. This scenario can be achieved with replaceable or recoverable energy absorbing element(s). The coupler system, if of the folding or retractable type, may or may not be deployed into its extended position as per normal operation.
(2) Scenario 2 (Safe-Speed Collision). This is a significant collision speed impact between two like LRVs or streetcars. It is indicated as the safe-speed collision because in this scenario, all the protection measures for the operator and passengers are fulfilled. These protection measures include minimal reductions in the occupied volumes and limits on average collision acceleration.
(3) Scenario 3 (Structural Stability Collision). This is a severe collision speed impact between two like LRVs or streetcars and is intended only to evaluate structural stability.
(4) Scenario 4 (Collision With Street Vehicles). This collision limits the damage to the LRV or streetcar in collisions with street vehicles and provides a level of protection to the occupants of the street vehicles.
Tables 4-1 and 4-2 further specify required design loads and strengths of structural elements such as collision posts and corner posts, side walls, end sills, and equipment attachments to protect passengers and operators from structural penetration, free-flying objects, and loss of occupant volume in the event of a collision with another vehicle or obstruction.
Section 10 describes the test principles used to verify that the crashworthiness requirements in Tables 4.6-1 and 4.6-2 are met.
5 DESIGN LOADS AND ASSESSMENT CRITERIA.