Research to develop new technologies for increasing the safety of passengers and crew in rail equipment is being directed by the Federal Railroad Administration’s (FRA’s) Office of Research, Development, and Technology. Crash energy management (CEM) components which can be integrated into the end structure of a locomotive have been developed: a push-back coupler and a deformable anti-climber. These components are designed to inhibit override in the event of a collision. The results of vehicle-to-vehicle override, where the strong underframe of one vehicle, typically a locomotive, impacts the weaker superstructure of the other vehicle, can be devastating. These components are designed to improve crashworthiness for equipped locomotives in a wide range of potential collisions, including collisions with conventional locomotives, conventional cab cars, and freight equipment. Concerns have been raised in discussions with industry that push-back couplers may trigger prematurely, and may require replacement due to unintentional activation as a result of loads experienced during service and coupling. Push-back couplers (PBCs) are designed with trigger loads meant to exceed the expected maximum service and coupling loads experienced by conventional couplers. Analytical models are typically used to determine these trigger loads. Two sets of coupling tests have been conducted that validate these models, one with a conventional locomotive equipped with conventional draft gear and coupler, and another with a conventional locomotive retrofit with a PBC. These tests allow a performance comparison of a conventional locomotive with a CEM-equipped locomotive during coupling, as well as confirmation that the PBC does not trigger at speeds below typical coupling speeds. In addition to the two sets of coupling tests, car-to-car compatibility tests of CEM-equipped locomotives, as well as a train-to-train test are also planned. This arrangement of tests allows for evaluation of the CEM-equipped locomotive performance, as well as comparison of measured with simulated locomotive performance in the car-to-car and train-to-train tests. The conventional coupling tests and the CEM coupling tests have been conducted, the results of which compared favorably with their pre-test predictions. In the CEM coupling tests, the PBC triggered at a speed well above typical coupling speeds. This paper provides a comparison of the conventional coupling test results with the CEM coupling test results. The next test in the research program is a vehicle-to-vehicle impact test. This paper describes the test preparation, test requirements, and analysis predictions for the vehicle-to-vehicle test. The equipment to be tested, track conditions, test procedures, and measurements to be made are described. A model for predicting the behavior of the impacting vehicles and the CEM system has been developed, along with preliminary predictions for the vehicle-to-vehicle test.

This work intends to lay the groundwork for Computer Aided Engineering (CAE)-based occupant safety of a typical tier-III Indian Railway (IR) passenger coach in a collision accident. Our previous work presented in International Crashworthiness Conference 2010 under the title “Simulation of Crash Behaviour of a Common Indian Railway Passenger Coach” provided crashworthiness assessment of a typical tier-III passenger coach structure for representative head-on collision scenarios namely, against an identical passenger coach and against a stationary locomotive. These scenarios were envisioned to be part of a bigger accident scenario e.g - head-on collision between two trains moving towards each other. Analysis of involved chain of events for entire rolling stock and resulting internal collisions between individual passenger cars was out of scope of this work and necessary inputs were obtained from available literature on the same. This work used a full scale Finite Element (FE) simulation model and commercial explicit solver LS-Dyna. FE model was validated using International Railway Union (UIC) code OR566 specified proof loads for design. Simulation methodology used for dynamic impact was validated by component level crushing experiments using a drop tower facility. Material modelling incorporated strain rate effect on yield strength which is essential for obtaining accurate structural deformations under dynamic impact loading. Contacts were modelled using the penalty method option provided by the solver. This model was simulated for collisions at 30, 40 and 56 km/h against a stationary rigid barrier. Collision speeds were chosen to simulate impact energies involved in collision scenarios as mentioned above. The structure was found to exhibit global bending deformation and jackknifing with pivot position at the door section. In this paper, we present an extension of this work — coupled occupant safety simulation and injury assessment. It was accomplished by recording head, neck, chest and knee responses of a Hybrid-III 50 th percentile male Anthropomorphic Test Device (ATD) FE model, seated in passenger position on lower berth of the first cabin of a passenger car. Interiors were modelled to represent the actual structure. Dummy model was adapted to passenger cabin’s excessive mobility conditions and responses were revalidated against Federal Motor Vehicle Safety Standards (FMVSS) limits. Injury interpretation was based on Abbreviated Injury Scale (AIS), automotive injury criteria and injury risk curves for Head Injury Criterion (HIC), thoracic spine acceleration, neck bending moment in flexion and extension and knee force. This study provides with estimates of injury and fatality based on computer simulation of accident scenarios. However, attempts of correlating to any available injury and fatality statistics were out of scope of this study.

Research to develop new technologies for increasing the safety of passengers and crew in rail equipment is being directed by the Federal Railroad Administration’s (FRA’s) Office of Research, Development, and Technology. Crash energy management (CEM) components which can be integrated into the end structure of a locomotive have been developed: a push-back coupler and a deformable anti-climber. These components are designed to inhibit override in the event of a collision. The results of vehicle-to-vehicle override, where the strong underframe of one vehicle, typically a locomotive, impacts the weaker superstructure of the other vehicle, can be devastating. These components are designed to improve crashworthiness for equipped locomotives in a wide range of potential collisions, including collisions with conventional locomotives, conventional cab cars, and freight equipment. Concerns have been raised in discussions with industry that push-back couplers may trigger prematurely, and may require replacement due to unintentional activation as a result of service loads. Push-back couplers (PBCs) are designed with trigger loads meant to exceed the expected maximum service loads experienced by conventional couplers. Analytical models are typically used to determine these required trigger loads. Two sets of coupling tests have been conducted to demonstrate this, one with a conventional locomotive equipped with conventional draft gear and coupler, and another with a conventional locomotive retrofit with a push-back coupler. These tests will allow a performance comparison of a conventional locomotive with a CEM-equipped locomotive during coupling. In addition to the two sets of coupling tests, car-to-car compatibility tests of CEM-equipped locomotives, as well as a train-to-train test are also planned. This arrangement of tests allows for evaluation of the CEM-equipped locomotive performance, as well as comparison of measured with simulated locomotive performance in the car-to-car and train-to-train tests. The coupling tests of a conventional locomotive have been conducted, the results of which compared favorably with pre-test predictions. This paper describes the results of the CEM-equipped locomotive coupling tests. In this set of tests, a moving CEM locomotive was coupled to a standing cab car. The primary objective was to demonstrate the robustness of the PBC design and determine the impact speed at which PBC triggering occurs. The coupling speed was increased for each subsequent test until the PBC triggered. The coupling speeds targeted for the test were 2 mph, 4 mph, 6 mph, 7 mph, 8 mph, and 9 mph. The coupling speed at which the PBC triggered was 9 mph. The damage observed resulting from the coupling tests is described. Prior to the tests, a lumped-mass model was developed for predicting the longitudinal forces acting on the equipment and couplers. The test results are compared to the model predictions. Next steps in the research program, including future full-scale dynamic tests, are discussed.

In this study, a Secondary Impact Protection System (SIPS) consisting of an airbag and a deformable knee bolster for use on a modern freight locomotive was developed and tested. During rail vehicle collisions, a modern locomotive designed to current crashworthiness requirements should provide sufficient survival space to the engineer in cab. However, without additional protection against secondary impacts, a locomotive engineer could be subjected to head, neck, and femur injuries that exceed the limits specified in the Federal Motor Vehicle Safety Standards (FMVSS 208). The SIPS study aimed to design a system that would control these injuries within the limiting criteria. Simulation results for the design concept showed that it would meet the FMVSS 208 criteria for the head, neck, chest, and femur, injuries and continuing to meet all existing functional requirements of the locomotive cab. A sled testing of the prototype showed that to optimize the SIPS, further airbag design modifications, characterization and testing are required.

Modern freight locomotives are built to crashworthiness standards that are defined in Subpart D of Code of Federal Regulations (CFR) Part 229 and Association of American Railroads (AAR) S-580 standards [1, 2]. The first freight locomotive crashworthiness standard, AAR S-580, was released in 1989 and became effective as of August 1990 [3]. Locomotives that were manufactured before the 1990, so-called “legacy”, lack the crew protection offered by the modern “crashworthy” locomotives [4]. While legacy locomotives, such as narrow-nose designs that were manufactured before 1990s, are generally relegated to non-lead locomotive service in Class I railroads, these units are sometimes used in mainline service. Even though the number of narrow-nose locomotives has declined, there remains a risk of injuries and fatalities for the crew for the next several years. The scope of this study is the following; • The assessment of injuries and fatalities from collisions involving legacy locomotives, • The crashworthiness evaluation of collision posts for a sample legacy (narrow-nose, legacy) locomotive assembled in the 1960s and rebuilt in 2001, • Analysis of alternative collision post designs to meet and exceed the collision post requirements in the 2001 version of AAR S-580.

The Federal Railroad Administration’s Office of Research and Development is conducting research into passenger locomotive fuel tank crashworthiness. A series of impact tests is being conducted to measure fuel tank deformation under two types of dynamic loading conditions — blunt and raking impacts. The results of this research program assist in development of appropriate standards for puncture resistance requirements to be applied to alternatively-designed fuel tanks, such as on diesel multiple unit (DMU) passenger rail equipment. This paper describes the results of the first blunt impact test performed on a DMU fuel tank. On June 28, 2016, FRA performed a dynamic impact test of a fuel tank from a DMU rail vehicle. The test was performed at the Transportation Technology Center (TTC) in Pueblo, Colorado. An impact vehicle weighing approximately 14,000 pounds and equipped with a 12-inch by 12-inch impactor head struck the bottom surface of a DMU fuel tank mounted vertically on an impact wall. The impact occurred on the bottom of the fuel tank at a location centered on two baffles within the fuel tank. The target impact speed was 11.5 mph, and the measured impact speed 11.1 mph. The test resulted in a maximum indentation of approximately 8 inches, the bottom of the tank bending away from the wall, and buckling of several internal baffles. Following the test, the tank was cut open to inspect the damage to the internal structure. This revealed that the buckling behavior of the baffles was isolated to the baffles immediately adjacent the impact location, each one buckling as the tank deformed inward. Prior to the test, finite element analysis (FEA) was used to predict the behavior of the tank during the test. The FE model of the tank required material properties to be defined in order to capture plastic deformation. The combination of metal plasticity, ductile failure, and element removal would permit the model to simulate puncture for this tank at sufficiently-high impact speeds. The pre-test FE model results compared very favorably with the test measurements, and both the pre-test model and the test resulted in similar modes of deformation to the DMU fuel tank. Following the test, material coupons were cut from undamaged areas of the fuel tank and subjected to tensile testing. The post-test FE model was updated with the material behaviors from the post-test material testing. This test is part of a research program investigating puncture resistance of passenger locomotive fuel tanks. The objective of this research program is to establish the baseline puncture resistance of current locomotive fuel tanks under dynamic impact conditions and to develop performance requirements for an appropriate level of puncture resistance in alternative fuel tank designs, such as DMU fuel tanks. Future tests are planned within this research program. The lessons learned during the series of tests support finite element (FE) modeling of impact conditions beyond what was tested. Additional tests investigating the puncture resistance of fuel tanks during sideswipe or raking collisions are also planned.

Research to develop new technologies for increasing the safety of passengers and crew in rail equipment is being directed by the Federal Railroad Administration’s (FRA’s) Office of Research, Development, and Technology. Crash energy management (CEM) components which can be integrated into the end structure of a locomotive have been developed: a push-back coupler and a deformable anti-climber. These components are designed to inhibit override in the event of a collision. The results of vehicle-to-vehicle override, where the strong underframe of one vehicle, typically a locomotive, impacts the weaker superstructure of the other vehicle, can be devastating. These components are designed to improve crashworthiness for equipped locomotives in a wide range of potential collisions, including collisions with conventional locomotives, conventional cab cars, and freight equipment. Concerns have been raised in discussions with industry that push-back couplers may trigger prematurely, and may require replacement due to unintentional activation as a result of service loads. Push-back couplers are designed with trigger loads meant to exceed the expected maximum service loads experienced by conventional couplers. Analytical models are typically used to determine these required trigger loads. Two sets of coupling tests are planned to demonstrate this, one with a conventional locomotive equipped with conventional draft gear and coupler, and another with a conventional locomotive retrofit with a push-back coupler. These tests will allow a performance comparison of a conventional locomotive with a CEM-equipped locomotive during coupling. In addition to the two sets of coupling tests, car-to-car compatibility tests of CEM-equipped locomotives, as well as a train-to-train test are also planned. This arrangement of tests allows for evaluation of the CEM-equipped locomotive performance, as well as comparison of measured with simulated locomotive performance in the car-to-car and train-to-train tests. The coupling tests of a conventional locomotive have been conducted, the results of which compared favorably with pre-test predictions. In the coupling tests of a CEM-equipped locomotive, the coupling speed for which the push-back coupler (PBC) triggers will be measured. A moving, CEM-equipped locomotive will be coupled to a standing cab car. The coupling speed for the first test will be low, approximately 2 mph. The test will then be repeated with the speed increasing incrementally until the PBC triggers. This paper describes the fabrication, retrofit, test requirements, and analysis predictions for the CEM coupling tests. The equipment to be tested, track conditions, test procedures, and measurements to be made are described. A model for predicting the longitudinal forces acting on the equipment and couplers has been developed, along with preliminary predictions for the CEM coupling tests.

Train carbody and truck structures are designed to exhibit primary natural frequency modes great enough to avoid unwanted resonant oscillations with normal track interactions. Critical bounce modes can be excited by typical track in the 2–4 Hz range. Trains are designed with first modes above this threshold. Historically, simplified approaches are employed to predict natural frequencies of the main truck and carbody train structures independently. Since the advent of high powered computing, more detailed finite element analysis (FEA) eigenvalue approaches have been used to more accurately predict natural frequency of structures. Still, the typical FEA approach uses simplified boundary conditions and partial models to determine natural frequencies of individual components, neglecting the interaction with other connected structures. In this paper, a detailed, holistic approach is presented for an entire Light Rail Vehicle (LRV). The analysis is performed on a fully detailed FEA model of the LRV, including trucks and suspension, carbody structures, non-structural mass, articulation, as well as intercar and truck-carbody connections. The model was developed for detailed crashworthiness investigations, which requires a high level of fidelity compared to what is typically required for static and modal analysis. Using the same model for multiple purposes speeds up development while also improving the accuracy of the analyses. In this paper, the modal analysis methodology developed is described. A case study is presented investigating the often neglected contribution of windows, cladding, and flooring on the overall carbody natural frequency.

Research to facilitate industry efforts to safely use natural gas as a locomotive fuel is being directed by the Federal Railroad Administration’s (FRA’s) Office of Research, Development, and Technology. This research is being conducted cooperatively with the Association of American Railroads (AAR). The research results are being shared with the AAR’s Natural Gas Fuel Tender Technical Advisory Group (NGFT TAG), which includes AAR, Member Railroads, and FRA, with support from ARA and Volpe Center. The NGFT TAG is developing industry requirements, including crashworthiness requirements, for revenue-service natural gas fuel tenders. Five accident scenarios have been drafted by the NGFT TAG: a train-to-train collision, a grade-crossing collision, rollover, shell impact, and head impact. Each scenario includes a description of the equipment, the impact conditions, and the prescribed outcome. Conceptually, these tender scenarios parallel the scenarios described in 49 CFR Part 229 Appendix E for locomotive crashworthiness. The focus of the NGFT TAG discussions has expanded to include alternative static requirements. Conceptually, the tender static requirements parallel the requirements for locomotive crashworthiness in AAR S-580. Requirements in S-580 for locomotive structure include static load capacities, material properties, and material thicknesses. For conventionally-designed locomotives, meeting the static requirements of S-580 is accepted as meeting the dynamic requirements of Appendix E. The tender static requirements under development are intended to provide the same level of crashworthiness as the previously proposed dynamic requirements. The primary advantage of static crashworthiness requirements is that compliance can be shown with classical closed-form engineering analyses. A disadvantage is that design features are presumed, such as the inclusion and location of collision posts in a conventional locomotive design. Design features are not presumed in dynamic crashworthiness requirements; however, compliance must be shown with a design-specific validated computer simulation model. So while dynamic requirements allow for a wide range of design approaches, showing compliance often requires extensive effort. This paper focuses on technical information to help support development of alternative static requirements for the train-to-train collision scenario. The goal of the static requirements is to provide the same level of crashworthiness as the dynamic requirements under discussion by the NGFT TAG. Tender features capable of providing the desired level of performance are proposed. These features have been selected such that a tender with these features would be crashworthy-compatible with a wide range of new and existing locomotive structural designs.

Research to develop new technologies for increasing the safety of passengers and crew in rail equipment is being directed by the Federal Railroad Administration’s (FRA’s) Office of Research, Development, and Technology. Crash energy management (CEM) components which can be integrated into the end structure of a locomotive have been developed: a push-back coupler and a deformable anti-climber. These components are designed to inhibit override in the event of a collision. The results of vehicle-to-vehicle override, where the strong underframe of one vehicle, typically a locomotive, impacts the weaker superstructure of the other vehicle, can be devastating. The components are designed to improve crashworthiness for equipped locomotives in a wide range of potential collisions, including collisions with conventional locomotives, conventional cab cars, and freight equipment. Concerns have been raised in discussions with industry that push-back couplers may trigger prematurely, and may require replacement due to unintentional activation as a result of service loads. It has been shown analytically that push back coupler trigger loads exceed the service load capacity of conventional couplers and draft gears. Two sets of coupling tests are planned to demonstrate this, one with a locomotive equipped with conventional draft gear and coupler and another with a locomotive equipped with a pushback coupler. These tests allow for comparison of conventional with CEM-equipped locomotive measured performance during coupling. In addition to the coupling tests, car-to-car compatibility tests of equipped locomotives and a train-to-train test are also planned. This arrangement of tests allows for evaluation of the CEM-equipped locomotive performance, as well as comparison of measured with simulated locomotive performance in the car-to-car and train-to-train tests. In the coupling tests of conventional equipment, the maximum coupling speed for which there is no damage to either vehicle will be measured. A moving locomotive will be coupled to a standing cab car. The coupling speed for the first test will be 2 mph, the second test 4 mph, and the tests will continue with the speed incrementing by 2 mph until damage occurs to either vehicle. This paper describes the test requirements and analysis predictions for the coupling tests of conventional equipment. The equipment to be tested, track conditions, test procedures, and measurements to be made are described. A one-dimensional model for predicting the longitudinal forces acting on the equipment and couplers has been developed, along with preliminary predictions for the conventional coupling tests. It is expected that damage will occur for coupling speeds between 6 and 8 mph.

Twenty-three commuter and inter-city passenger train accidents, which occurred over the past twenty years, have been analyzed. The analysis has assessed the potential effectiveness of various injury mitigation strategies. The strategies with the greatest potential to increase passenger safety are interior occupant protection, coupler integrity, end structure integrity, side structure integrity, and glazing system integrity. We recommend that these strategies be researched further. Three types of accidents were analyzed: train-to-train collisions, derailments, and grade-crossing collisions. Train-to-train collisions include the commuter train-freight train collision in Chatsworth, California on September 12, 2008. In Chatsworth a commuter train collided with a freight train at a closing speed of ∼80 mph, fatally injuring twenty-five people and injuring more than 100 others. Derailments include the commuter train derailment in Spuyten Duyvil, New York on December 1, 2013, fatally injuring four people and injuring more than fifty others. Grade-crossing accidents include the commuter-SUV collision in Valhalla, New York on February 3, 2015, which resulted in six fatally injured people, including the SUV driver, and thirteen severely injured people. Four categories of mitigation strategies were considered: train crashworthiness, wayside structure crashworthiness, fire safety, and emergency preparedness. Within each of these categories are equipment features, which may potentially be modified to further mitigate injuries. The features are simple noun phrases, e.g., “floor strength,” implying that the floor strength should be increased. Train crashworthiness includes features such as end strength, floor strength, coupler separation, and numerous others. Wayside structure crashworthiness includes features such as frangible catenary poles and third rail end caps. Fire safety includes train interior and train exterior features for minimizing the potential for fire and for reducing the rate at which fire might spread. Emergency preparedness includes features for emergency egress, access, lighting, signage, and on-board equipment, such as fire extinguishers. Overall, rail passenger travel has a high level of safety, and passenger train accidents are rare events. The numbers are low for expected casualties per passenger-mile and casualties per passenger-trip. A high level of safety, however, does not mean efforts to improve it should cease. But it does mean that crashes are rare events. Rare events in complex systems are notoriously difficult to analyze with confidence. There are too few accidents to provide the data needed for even a moderate degree of mathematical confidence in statistical analysis. Analyses of similar data in medical and scientific fields have been shown to be prone to the biases of the researchers, sometimes in subtle and difficult-to-detect ways. As a means of coping with the sparse data and potential biases, the goal has been to evaluate the accidents transparently and comprehensively. This approach allows a wide audience to understand how injuries and fatalities occur in passenger train accidents and, most importantly, allows us to prioritize mitigation strategies for research.

The Federal Railroad Administration’s Office of Research and Development is conducting research into passenger locomotive fuel tank crashworthiness. A series of impact tests is being conducted to measure fuel tank deformation under two types of dynamic loading conditions — blunt and raking impacts. This program is intended to result in a better understanding of design features that improve the puncture resistance of passenger locomotive fuel tanks. One reason for performing this program is to aid in development of appropriate standards for puncture resistance to be applied to alternatively-designed fuel tanks, such as on diesel multiple unit (DMU) passenger rail equipment. This paper describes the results of the third blunt impact test of retired F-40 locomotive fuel tanks. The test setup was designed for the Transportation Technology Center (TTC) in Pueblo, Colorado, to impart blunt impacts to the bottom of each fuel tank specimen. The specimens tested to date are from FRA-owned retired F-40 passenger locomotives. To conduct the test, each tank was emptied of fluid and mounted on a crash wall with the bottom surface exposed. A rail cart modified with a “rigid” indenter measuring 12 inches by 12 inches, was released to impact the bottom of fuel tank at a target impact speed. The first two tests, conducted on October 8 and 9, 2013, were designed to impact the center of two different tank designs. Tests were conducted at impact speeds of 4.5 and 6.2 mph and caused maximum residual dents of 5 inches and 1.5 inches, respectively. On August 20, 2014 the test of fuel tank 234 was conducted to impact the tank off-center between two baffles. Force-deformation measurements were collected for each tank during the three tests. The series of tests provide information regarding the influence of tank design on puncture resistance. In the test of tank 234, the target impact speed was 12.5 mph, and the actual impact occurred at 11.2 mph. The test resulted in a residual dent depth of approximately 9 inches, and buckling of several internal baffles. The impact did not result in puncture of the tank. Following the test, the tank was cut open to permit examination of the baffles. This examination revealed a different baffle geometry than was modeled based on pre-test measurements. Finite element analysis (FEA) was used to predict the behavior of the tank during the test. The FE model of the tank required several material properties to be defined in order to capture puncture behavior. The combination of metal plasticity, ductile failure, and element removal would permit the model to simulate puncture for this tank. Following the test, the tank was cut open, revealing a different baffle arrangement than had been initially thought. The post-test FE model was then updated to include the actual baffle arrangement of tank 234. With the actual baffle arrangement included in the model, the FE results are in fairly good agreement with the test. Additional changes to the ductile failure criterion were also made in the post-test model. The objective of this research program is to establish the baseline puncture resistance of current passenger locomotive fuel tanks under dynamic impact conditions and to develop performance requirements to ensure an appropriate level of puncture resistance in alternative fuel tank designs, such as DMU fuel tanks.

The potential opportunities for fuel cost and emissions reduction as a result of converting from diesel to natural gas (NG) are well known in the rail industry. Recent developments in domestic sources for petroleum have both lowered the cost and stabilized the natural gas market making the adoption of NG more strategically viable than ever before. NG Engine conversion systems for medium speed diesel engines have been available for over 20 years and environmental incentives are helping to further support the adoption of NG not only as an alternate fuel, but possibly as the new primary fuel. The major challenge for railroad transition to NG is now to develop a manageable and cost effective on board storage architecture with capacity to provide sufficient range to meet industry acceptance for general use. For long haul applications, the solution has been to add a large locomotive NG tender. For short line, switcher and commuter applications, the fuel cost benefits do not warrant the cost and complexity of such a system. For these short to medium range applications, an “on locomotive” storage system with a capacity equivalent to a minimum of 500 diesel gallons is a better solution. This paper summarizes the development of a crashworthy, high capacity, underframe NG storage solution packaged in the form factor normally occupied by the conventional locomotive diesel fuel tank (Fig. 1). Primary challenges for the CNG storage system solution are to achieve high storage density and crashworthiness while within the confines of existing AAR M-1001Plate C profile. It is expected that the system is to meet both the CFR/FRA structural requirements for diesel tanks and relevant DOT requirements for CNG cylinders used in mobile applications. The NG storage system presented consists of an outer enclosure which mounts to the locomotive similarly to the existing diesel fuel tank. The enclosure contains and interfaces with NG cylinders specifically designed for the application. The system design withstands the various load requirements defined in 49 CFR Part 238 Appendix D, that simulate both jackknife derailment and class 8 truck side impact scenarios. NG cylinders within the enclosure must be approved for use in this application and have sufficient capacity and maintainability to create new opportunities for NG conversion in the rail industry. The primary design goal for the storage system is to integrate the cylinder size and configuration within the enclosure such that storage volume is maximized and crash impact loads are minimized. Impact loads are distributed through the system ensuring that point loading sufficient to breach one or more of the NG cylinders or fuel lines does not occur. An overview of the development and results of physical derailment and side impact testing performed in support of this effort are presented.

The design of freight locomotives for U.S. railroads began changing in late-1990 with the introduction of the first industry crashworthiness standard for the front nose of newly-manufactured freight. Between 1990 and 2008, that industry standard was revised and upgraded four times. In 1995 an industry standard for the crashworthiness of fuel tanks mounted underneath newly-manufactured freight locomotives was also introduced. Effective at the end of 2008, both of the industry standards were incorporated by reference into a new U.S. federal regulation mandating crashworthiness features on newly-manufactured locomotives effective with deliveries to railroads in 2009. In addition to the crashworthiness-specific design changes, in 1992 and 1993 both of the major U.S. locomotive manufacturers introduced new designs for the attachment of the truck (bogie) assemblies to locomotive underframes; these changes were to facilitate the use of new trucks (bogies) producing higher adhesion for greater tractive effort. The “deep traction pin” designs also had a positive effect on the crashworthiness of new fuel tanks by reducing the chance of truck separation from the underframe (and impacting the fuel tank) during accidents. The changes cited here were for newly-manufactured freight locomotives, with retrofit to older locomotives impossible or extremely difficult to accomplish with similar results. This paper briefly reviews the introduction of the crashworthiness features described, and also offers the first retrospective look at (a) how extensively the evolving crashworthiness features have reached across the U.S. freight locomotive fleet (through acquisition of newly-manufactured freight locomotives) and (b) attempts to measure the effectiveness of the various crashworthiness design changes in saving lives and reducing injuries of in-cab railroad employees. It is believed that this paper is the first and only assessment to date of cumulative U.S. freight locomotive crashworthiness progress and its statistical impact on locomotive crew safety since the early 2000’s.

The extensive North American freight rail network is currently operated with diesel as the sole fuel source. However, the Class 1 railways have recently started to explore Liquefied Natural Gas (LNG) as an alternative fuel source, which has a lower environmental impact and could provide fuel cost savings compared to diesel. The efforts to develop industry standards for fuel tenders is being led under the Association of American Railroads (AAR) Natural Gas Fuel Tender (NGFT) Technical Advisory Group (TAG), a joint effort of the AAR Locomotive, Tank Car, and Equipment Engineering Committees, with multiple participants from industry. A significant section of the standards for LNG tenders are the performance requirements to ensure safety in collisions. As part of this effort, the NGFT TAG has been working in partnership with the Federal Railroad Administration (FRA) to define a suitable set of collision load cases and associated safety performance requirements. In support of these efforts, a series of analyses have been performed for the various collision load cases to support the development of suitable methodologies to evaluate the load cases and inform the NGFT TAG and other stakeholders related to the safety performance of NGFT designs. Results from these efforts are described in this paper.

Research is being conducted to develop technical information needed to formulate effective natural gas fuel tender crashworthiness standards. This research is being performed for the Federal Railroad Administration’s (FRA’s) Office of Research, Development, and Technology, and intended to facilitate industry efforts to use natural gas as a locomotive fuel. Strategies to assure crashworthiness during moderate accidents, such as train-to-train collisions at speeds up to 40 mph, are being evaluated. This research applies the approach FRA has used to develop technical information on locomotive, hazmat tank car, and diesel fuel tank crashworthiness. There are four primary tasks: 1. Definition of collision scenarios 2. Evaluation of traditional designs 3. Evaluation of alternative designs 4. Recommendation of effective crashworthiness strategies The tender scenarios have been drafted from reviews of freight train accidents and of scenarios developed for locomotives, hazmat tank cars, and fuel tanks. From these reviews, five scenarios were selected. These scenarios are intended to bound the range of collisions that a tender may experience, are being used to evaluate the crashworthiness of traditional tender designs, and will be used to evaluate alternative design tenders. The five candidate scenarios are: 1. Train-to-train collision 2. Grade-crossing accident 3. Tender derailment and rollover 4. Impact into tender tank shell during derailment 5. Impact into tender tank head during derailment As part of previous research on locomotives and passenger equipment, a range of crashworthiness analysis techniques were developed. These include simplified techniques, which can be performed rapidly and provide essential results, and detailed computer simulations which provide a wealth of information. The crashworthiness performance of a hypothetical tender design has been evaluated using simplified techniques. Simplified techniques include quasi-static crush analysis of structural elements and lumped-parameter analysis of train dynamics. The results suggest that efforts to enhance crashworthiness should principally be directed toward the train-to-train scenario. Work is ongoing to develop strategies for improving tender crashworthiness. This research is being conducted cooperatively with the Association of American Railroads (AAR). The research results are being shared with the AAR’s Natural Gas Fuel Tender Technical Advisory Group (NGFT TAG). The NGFT TAG is developing industry standards, including crashworthiness requirements, for revenue-service natural gas fuel tenders. There is a companion paper which describes crashworthiness research sponsored by AAR, including detailed computer simulations of tender crashworthiness. This paper describes development of scenarios and simplified analyses of tender crashworthiness.

There has been significant research in recent years to analyze and improve the impact behavior and puncture resistance of railroad tank cars. Ultimately, the results of this work will be used by the Government regulatory agencies in the United States and Canada to establish performance-based testing requirements and to develop methods to evaluate the crashworthiness and structural integrity of different tank car designs. This paper describes results of recent side impact testing and corresponding analyses using detailed finite element analyses (FEA). The test and analyses were performed to evaluate the side impact puncture performance of DOT-111 tank cars. The tank car was filled with water to approximately 97 percent of the volume. The tank was then sealed but not pressurized. The tank car was impacted at the Transportation Technology Center, Inc. by a 297,125-pound ram car with 12-by 12-inch ram head fitted to the ram car impacted the tank center. The analyses were on overall good agreement with the measured impact response. The lading was found to play a more significant role in the impact response than in previous testing and analyses of pressure tank cars. This is not surprising considering the reduced structural stiffness of the tanks compared to thicker pressure tank cars and the reduced effective stiffness from the initially unpressurized tank at impact. The smaller outage volume also contributes to a dramatic increase in the tank pressure as the dent formation reduces the tank volume and compresses the contents of the tank.

The Office of Research, Development, and Technology of the Federal Railroad Administration (FRA) and the Volpe Center are continuing to evaluate new technologies for increasing the safety of passengers and operators in rail equipment. The results of vehicle-to-vehicle override, where the strong underframe of one vehicle, typically a locomotive, impacts the weaker superstructure of the other vehicle, can be devastating. Crashworthy components which can be integrated into the end structure of a locomotive have been developed to inhibit override in the event of collision. Recent research has resulted in the development of a design concept, including evaluation with finite-element analysis (FEA), fabrication, and component tests. The design concept developed incorporates two key components: a push-back coupler and a deformable anti-climber. Detailed designs for these components were developed and the performance of the designs was evaluated through large deformation dynamic FEA. Test articles were fabricated and dynamically tested to verify their individual performance characteristics. The tests were successful in demonstrating the required performance of the components. Test results were consistent with finite element model predictions of energy absorption capability, force-displacement behavior, and modes of deformation. Work is ongoing to retrofit these crashworthy components onto conventional locomotives and conduct full-scale dynamic impact tests of colliding cars, as well as colliding trains. Service tests will be performed to measure the impact speed at which push-back coupler triggering occurs. Vehicle-to-vehicle tests will be conducted to demonstrate the performance of the crashworthy components working together as an integrated system. The vehicle-to-vehicle tests will also allow an evaluation of the crashworthiness compatibility of a modified locomotive with a range of equipment, including conventional locomotives, cab cars, and freight cars. Train-to-train tests are planned to demonstrate incremental improvement, increased crashworthiness, compatibility, and serviceability. This paper describes the tests that are planned to demonstrate the behavior of these components when they are integrated into the end structure of a locomotive. The tests will demonstrate the in-service and crashworthiness performance of the modified locomotives. This research program endeavors to advance locomotive crashworthiness technology and develop the technical basis for generating specifications for push-back couplers and deformable anti-climbers.

The Federal Railroad Administration’s Office of Research and Development is conducting research into fuel tank crashworthiness. A series of impact tests are planned to measure fuel tank deformation under two types of dynamic loading conditions — blunt and raking impacts. This paper describes the results of the first set of blunt impact tests for two retired EMD F-40 locomotive fuel tanks, Tank 232 and Tank 202. On October 8, 2013 and October 9, 2013, the FRA performed impact tests on two conventional passenger locomotive fuel tanks at the Transportation Technology Center (TTC) in Pueblo, Colorado. Each fuel tank was emptied of fluid and mounted on a crash wall with the bottom surface exposed. A rail cart modified with a “rigid” indenter was released to impact the center of the bottom of each fuel tank at about 6 mph. A center-impact on Tank 232 was chosen to impact between two baffles. A center-impact on Tank 202 was chosen to impact on a baffle. In the first test, Tank 232 was impacted by the indenter at 4.5 mph. The maximum residual indentation on the bottom of the tank measured approximately 5 inches. The tank deformed across the middle longitudinal span of the tank forming a diamond-shaped indention. In the second test, Tank 202 was impacted by the indenter at 6.2 mph. The maximum residual indentation on the bottom of the tank measured approximately 1.5 inches. The bottom of the tank deformed with an “X” shape spanning out from the location of square indenter at the center of the tank. Post-test autopsies revealed the deformation of the interior structures, i.e. baffles and attachments. There was no damage to the baffles in Tank 232. Deformation to the interior structure of Tank 202 was limited to the baffle directly beneath the impact location, which folded in the area near the impact location. Material coupons were cut and tensile testing performed to determine the properties of the materials used in each tank. Prior to the test, computer models were developed from measurements taken on the test articles. Material properties were estimated based on Brinell hardness measurements. Computer analyses were conducted to determine the conditions for the test, i.e. instrumentation, location of impact, target impact speeds and to predict the deformation behavior of the tank. Post-test, the resulting stress-strain relationships for the bottom sheets and baffles of both tanks were used to update the finite element models of the two tanks. The models were also updated to reflect the actual geometry of the tanks as confirmed by measurements of the tank interiors. The results of the finite element (FE) models run at the test conditions with the updated tank details are compared with the results from the test itself. Specifically, the deformation progression and the residual dent depth are compared between the tests and the models. In accidents, fuel tanks are subjected to dynamic loading, often including a blunt or raking impact from various components of the rolling stock or trackbed. Current design practice requires that fuel tanks have minimum properties adequate to sustain a prescribed set of static load conditions. Current research is intended to increase understanding of the impact response of fuel tanks under dynamic loading.

There has been significant research in recent years to analyze and improve the impact behavior and puncture resistance of railroad tank cars. Ultimately, the results of this work will be used by the Government regulatory agencies in the United States and Canada to establish performance-based testing requirements and to develop methods to evaluate the crashworthiness and structural integrity of different tank car designs. This paper describes analyses of current impact testing requirements and impact test methodologies using detailed finite element analyses (FEA). The results of these analyses are used to identify characteristics of the test methodologies that are desirable or undesirable for the test requirements in future tank car safety regulations.