Over the past several years, Carbuilders have been developing car designs that utilize Crash Energy Management (CEM) as an alternative means to demonstrate compliance with carbody structural strength requirements. With the onset of CEM designs, the CFR has been amended to include requirements for alternative compliance to carbody structure requirements (see Docket No. FRA-2013-0060, Notice No. 3, [the Final Rule]) [14]. CEM designs often utilize crush zones with the overall goal of protecting occupant volume. These designs also change the structural behavior of the car during an accident, resulting in different acceleration responses than conventional car designs. This paper seeks to compare and contrast the interior fitting strength requirements between conventional car designs and a generic CEM design. The methodology utilizes simple mathematical simulations, modeling a conventional car design and a CEM design, with outputs of the simulation consisting of car response and behavior. Results indicate that alternative compliance requirements for all tiers of CEM-designed passenger equipment should be considered for interior fixtures.

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.

Laser welding has received increased interest in the rail industry due to its outstanding performance in aesthetics, strength, heat affected area, precise control and sealing. This paper introduces the laser-welded stainless steel carbody used in subway cars. The carbody structure, welding methods, strength and fatigue analysis methods, and test verification and validation results are discussed. Firstly, the shear strength of laser welding on stainless steel with different thickness combinations were obtained through tests. The preliminary carbody structure was designed based on the material and welding properties. Then the finite element analysis (FEA) was conducted on the preliminary design to evaluate the strength and optimize the structure. After the optimization was completed, a full-size car was manufactured, and the strength test was performed. In the process of FEA and strength evaluation, the simulation accuracy of different element types and the influence of loading force directions have been considered. Based on the design, simulation and test data, a complete laser welding carbody strength evaluation system was established, which can provide valuable reference for researchers and engineers in the rail vehicle industry. The entire design, analysis and testing process complies with ASME-RT2-2014 and this is also one of the first to implement this standard.

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.

An important consideration when operating a fleet of passenger rail consists is the remaining service life of both the car structure and the trucks. Agencies may choose to undertake studies like this when considering a fleet wide capital improvement program, ranging from minor aesthetic upgrades to major system replacements and interior reconfigurations. With this in mind, the owner needs to determine the remaining fatigue life of the individual cars and trucks within the fleet. This paper describes the fitness-for-service (FFS) assessment performed on railcars and trucks and an example of the method applied in practice. To establish the current condition of the fleet, an initial structural and service history review was undertaken. In addition, nondestructive examinations (NDE) of a sample of cars and trucks were performed to investigate any regions that have experienced damage due to the years of service. After the baseline condition of the cars and trucks was determined, finite element analyses (FEA) were performed on both the cars and the trucks to assist in locating the potential fatigue critical regions. Strain gages and accelerometers were then installed on both the cars and trucks for field testing. Multiple runs of in-service testing were performed and a typical revenue service fatigue life of both the cars and trucks was calculated based on an S-N approach. Based on the calculated fatigue life and the current accumulated consist mileage, the remaining car and truck service lives were determined. For regions with known flaws more detailed fracture mechanics based crack growth analyses were developed to determine critical flaw sizes and their propagation times to critical from the known initial flaw sizes. Results of the FFS assessment provide information on the susceptible areas within the car structure and trucks. Depending on those results, decisions can be made on the required inspections, repairs, or decommissioning necessary to operate the fleet in the short term, while also providing valuable insight into long term fleet planning.

This Safety IDEA project-31 extends the design process for the accessible sleeper compartments to include 3-D digital modeling and anthropometric analyses and uses a full-scale soft mock-up of the sleeper compartment. The use of computer-aided design tools permits human factors constraints, including minimum spatial requirements and reach limitations, to be determined within the conceptual design phase without physical prototyping and data collection. In this ongoing study, physical prototyping in the form of a full-scale soft mock-up is used to validate digital results. Successful validation would indicate that anthropometric digital human models based on regular anthropometric databases may be used to design for populations with reduced mobility, provided that the wheeled mobility devices are modelled appropriately and advance the design process for accessible spaces. The soft mock-up permits spatial evaluation by the general public including people with disabilities. An online survey is also available to gather feedback and the needs and values of the target population. Representatives of the passenger rail industry are involved throughout the project and have been invited to participate in the evaluation of the soft mock up. The results of the project are validated designs for new accessible sleeper compartments for bi-level and single-level rail cars and include seating, sleeping, and restroom spaces. This will be disseminated for use by the passenger rail industry.

The Federal Railroad Administration (FRA) has partnered with Metro-North Railroad (MNR), Long Island Rail Road (LIRR) and New York & Atlantic Railway (NYA) to enhance operational safety through the implementation of wayside detection systems. Currently, MNR has a four-track Wheel Impact Load Detector (WILD) system that has been operating since 2010 near the Grand Central Terminal. This paper discusses a Receiver Operating Characteristic (ROC) analysis of this existing WILD system in conjunction with the wheel maintenance practices since 2010. Currently MNR’s operating procedures require a car with wheel(s) exhibiting a vertical peak load/mean load ratio, called dynamic ratio (DR), ≥3.0 to be shopped for repair. The analysis, using a 30-day repair window after detection, shows that 84% of the cars shopped for wheel(s) with DR≥3.0 required valid maintenance repairs. The minimum number of total false records (false positive + false negative records, combined) were observed within the DR range of 2.7–2.8 when considering wheel flat defects only. An analysis of the false negative records inclusive of both flat and shell spots, showed that the minimum number of false records dropped slightly to a DR range of 2.6–2.7. The reported ROC analysis shows that MNR’s current DR≥3.0 to trigger inspection and maintenance actions is reasonable.

Current standards such as NFPA 130 [1] require railcar floor assemblies to achieve a fire resistance rating according to ASTM E119 [2] by exposing the assemblies to a prescribed 30 minute time-temperature curve using a furnace. Though the ASTM E119 is a standard test procedure, it does not represent a real fire scenario which can have temporal and spatial varying exposure. This work developed a computational framework to evaluate and compare standard fire exposures such as ASTM E119 to real fire exposures to determine the difference in the temperature rise of a railcar floor assembly. The dimensions of the assembly used in this work consisted of the entire width of the railcar ∼3.0 m (10 ft) and a length of 3.7 m (12 ft) as described in NFPA 130. The real fire exposures simulated in this work have been identified in a review [3] of incidents involving fire exposures to railcars in the US and internationally over the past 50 years. The fire exposures consisted of a continuously fed diesel fuel spill, a localized trash fire, and a gasoline spill simulated from a collision of the railcar with an automobile. These realistic fire exposures were applied to a floor assembly model in Fire Dynamics Simulator (FDS) [4] which also included the undercarriage equipment to better capture the fire dynamics. The thermal exposure at the underside of railcar assembly was extracted using the heat transfer coefficient and the adiabatic surface temperature provided by FDS. These spatial-temporal exposures were coupled with a detailed railcar floor assembly finite element (FE) model in ABAQUS [5] to analyze the thermal behavior of the assembly. The thermal model in ABAQUS provided the evolution of temperature in different components of floor assembly consisting of a structural frame, insulation, and a composite floor. The standard scenarios were simulated for two hours instead of the typical 30 minutes to identify the appropriate exposure duration which can better represent a real fire scenario.

Developing of testing rigs represents a crucial activity for understanding the behavior of physical systems. A sloshing cargo in a railway tank car involves the dynamic interaction of the cargo-frame systems, characterized by lateral load transfers derived from the motion of the cargo. Such dynamic loads could develop a concentrated damage in the rail. While it has been recognized in the literature the influence of such dynamic sloshing forces on the wheel load exerted on the rails, affecting the lateral stability of the car and, consequently, the level of stress in the rail, no experimental validation has been made for none of these situations, namely, the effect of sloshing cargoes on the lateral stability of the cars, and on the corresponding stress level in the rails. In this paper, an experimental test rig is proposed to study the liquid cargo–tank car interaction when negotiating a turn. The equipment will provide the means to validate a simplified mathematical model, which will allow extensive parametric analyses.

Early detection of rail defects can avoid derailments and costly damage to the train and railway infrastructure. Small breaks, cracks or corrugations on the rail can quickly propagate after only a few train cars have passed over it, creating a potential derailment. The current technology makes use of a dedicated instrumented car or a separate railway monitoring vehicle to detect large breaks. These cars are usually equipped with accelerometers mounted on the axle or side frame. The simple detection algorithms use acceleration thresholds which are set at high values to eliminate false positives. As a result, rail surface defects that produce low amplitude acceleration signatures may not be detected, and special track components that produce high amplitude acceleration signatures may be flagged as defects. This paper presents the results of a feasibility study conducted to develop new and more advanced sensory systems as well as signal processing algorithms capable of detecting various rail surface irregularities. A dynamic wheel-rail interaction model was used to simulate train dynamics as a result of rail defects and to assess the potential of this new technology on rail defect detection. In a future paper, we will present experimental data in support of the proposed model and simulations.

The Train Energy and Dynamics Simulator (TEDS) is state-of-the-art simulation software, developed by the Federal Railroad Administration (FRA), to study train operation safety and performance as affected by a wide variety of rolling stock, track, train handling and operating configurations. As part of developing TEDS, existing and published data on braking, draft systems and train performance were used for initial validation of TEDS. This paper describes two revenue service tests conducted to further validate TEDS. The first test was on a loaded unit train, while the second test was on a mixed train with empty and loaded cars and included distributed power in which the remote brake valve was cut in. Collected test data included throttle position, train speed, locomotive power, brake system pressures and coupler forces. Several events from these tests, representing typical train operating scenarios, were selected for comparison with TEDS predicted results. The TEDS predictions matched the measured test data for all of the scenarios simulated, further validating the performance of the software and offering additional assurance on the use of TEDS for simulating performance and safety critical train dynamic behavior.

This paper deals with Physical Safety and Security at rail crossings. There are about 150,000 public railroad grade crossings in the U.S. Unfortunately, approximately 2,000 accidents occur every year in the U.S., resulting not only in many injuries, but also in over 200 deaths annually. The predicament is that for various reasons, people, cars, and trucks find themselves on the rail tracks of an oncoming train at a railroad crossing. The system discussed in this paper provides a relatively inexpensive Internet of Things (IoT)-based capability that can be used to alert a rail operator that there is an obstruction on the tracks, and/or possibly to interwork with (but not replace) a Positive Train Control (PTC) system thus attempting to automatically stop an incoming train. In fact, IoT is now being deployed in railroads for a variety of applications. A brief description of cybersecurity issues related to IoT deployment is also included.

Crude oil and ethanol unit train derailments sometimes result in the release of large volumes of flammable liquids which ignite and endanger the safety of persons, property, and the environment. Current methods to reduce the probability and mitigate the consequences of High-Hazard Flammable Train (HHFT) derailments include operational speed constraints, enhanced tank car design/build requirements, improved car and track inspection and maintenance, and use of advanced braking systems. The train brake system can dissipate more energy in a derailment scenario if the brake signal propagation rate is increased, the brake force against the wheel tread is increased, or a combined approach is used. This paper describes a simplified energy conservation model used to determine the emergency braking stopping distance and energy dissipation benefits available for three advanced train braking systems. A 3×3 matrix of brake configurations was defined by three brake signal propagation rates and three car net braking ratio (NBR) values. The brake signal propagation rate was modeled for trains with conventional head-end locomotive power, pneumatic car braking, and no two-way end-of-train device (CONV); locomotive distributed power with pneumatic car braking (trailing DP); and locomotive power with electronically-controlled pneumatic (ECP) braking. Car NBR values of 10, 12.8, and 14 percent were selected to reflect the expected brake force range available from older equipment in the existing tank car fleet (10% NBR) to the maximum acceptable value for new or rebuilt cars (14% NBR). Various in-train emergency brake application scenarios for loaded unit trains were modeled while accounting for the gross effects of derailment/collision blockage forces. Empirical data from four trailing distributed power train derailment events were used to estimate an average derailment/collision blockage force (ADF) and simulate the trailing consist braking performance. The ADF results were subsequently used in a more general tank car unit train parametric study to evaluate the effects of train speed, track grade, and in-train derailment position for each brake configuration in the matrix. The simplified energy conservation model was used to 1) quantify the number of trailing consist cars expected to stop short of the derailment location and 2) compare the car-by-car energy state of each car in the trailing consist that was calculated to reach the derailment location. Results for the empirical and parametric study cases are compared graphically and observations are discussed relative to two assumed baseline brake configurations.

This paper presents the result of an evaluation program for the condition of the SEPTA Broad Street subway car shells and their capability to perform during an extended period of revenue service. SEPTA currently is evaluating various system upgrades to address equipment obsolescence and reliability, and wanted to verify that the current car shells are expected to be serviceable during this extended period. The evaluation focused on two aspects of the 1982-built car shells. First, what is the current and predicted condition of the shells and, second, how does the performance of the current car shell design compare to present day designs and requirements? Four sets of activities were done as part of this project. One-third of the fleet was randomly chosen for visual inspections. Service-induced cracks were identified at two locations: in ring welds below the doors, and on the side sill between the corner posts and the anti-climbers. The ring weld cracks have been identified on a small number of cars in the past, and SEPTA continues to monitor and reinforce these areas. The cracks between the corner posts and anticlimbers are also being monitored; to date, none of these cracks has progressed to the point that repair is required. In parallel with the visual inspections, the car shell camber and doorway dimensions were measured on approximately 10% of the fleet. All the measured vehicles had positive camber; doorway dimensions were uniform, except for scattered individual measurements that were car-specific. This part of the evaluation concluded that the car shells are not undergoing significant degradation or cracking. One car was instrumented with strain gauges in potential high-stress areas, and then operated at simulated full passenger-load weight over the Broad Street route. Cyclic strains imposed by simulated revenue service were measured and converted to stresses. This testing confirmed high stresses at the joint between the side sill and the body bolster. The lifetime limiting location on the car shells is in the ring welds below the doors, consistent with the results of the visual inspections. Using conservative assumptions of continuous full passenger loading and minimum material properties, the predicted lifetime to the initiation of visible cracks in this area is 7–14 years of service. This independent evaluation is consistent with the actual experience, and provided confidence in the analysis protocol. SEPTA is monitoring this location and repairing cracks as required. Evaluation of the car shell design with regard to performance in a collision revealed that, unlike most other cars of its era, the Broad Street car shell contains provisions to manage energy absorption during a low-speed collision. Records obtained from a car repair shop showed that, when a Broad Street car had a significant non-revenue end collision, these provisions worked as intended to localize the deformation. In similar collisions, the Broad Street car shell will not perform significantly different from cars built to current industry practices. Results from this study indicate that with continued attention to car shell condition, including regular inspections and limited repairs, the Broad Street car shells will continue to be safe and serviceable for an extended period.

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.

It has been desirable for years to develop a reasonably simple, direct, accurate, and reliable method to measure pressure distributions in railroad trackbeds, especially the pressure magnitudes and distributions at the tie-ballast interface. In this study, specially-designed granular material pressure cells were used to measure pressure magnitudes and distributions. The cells were placed directly under the rail-tie intersection at the tie-ballast interface. Initially, a MTS test machine was used to conduct a series of laboratory tie-ballast box tests for a wide variation of ballast types and loading configurations. The adequacy of the cells for in-track measurements was verified with a series of very controlled laboratory tests and measurements using simulated trackbed sections and loading conditions. Excellent correlations were obtained comparing applied machine pressures and measured transferred cell pressures indicating that this type of pressure cell is suitable for in-track tie-ballast pressure measurements. This preliminary testing sequence is briefly described. A series of in-track wood tie tests were conducted on a yard lead track on a shortline railroad, Transkentucky Transportation, to optimize the in-track installation procedures and to obtain pressure measurements using repeated passes of low-speed locomotives and cars. A normalized pressure distribution was obtained by using metal shims when necessary to fill voids between the ties and pressure cells to insure continuous tie-ballast contact. This test sequence is presented and described. Additional in-track tests were conducted on Norfolk Southern Railway’s heavy tonnage concrete tie Class 4 mainline with train speeds of up to 64 km/h. Data was obtained for numerous passages of revenue trains over a period of several months for variable weights and types of locomotives and freight cars at typical train speeds. The average pressure intensities at the tie-ballast interface were acquired for six consecutive ties comprising a complete revolution of the wheels. This data is presented and the results discussed.

This work presents the results of a parametric study on the dynamic amplification or impact factor due to transit vehicles. The study was performed on a single span simply supported bridge composed of prestressed concrete bulb tee girders with a concrete deck and direct fixation track. The study varied the key parameters affecting the structural response of the bridge, viz. stiffness of the bridge, vehicle speed and axle configuration. The bridge was numerically modeled using CSI-Bridge software. Stiffness was manipulated in the models by varying the elastic modulus of the concrete. Vehicle speed varied form quasi-static speed of 0.45 m/s (1 mph) to 35.32 m/s (79 mph) in increments of 1.34 m/s (3 mph). Different axle configurations were obtained by modeling trains consisting of different numbers of cars as well as considering different light rail vehicle types. Light rail vehicles defined by transit agencies in Denver, Boston, Washington DC, Phoenix and Houston were considered, which provided a total of 22 different configurations. Vehicle lengths as well the number of axles and spacing between axles varied. The moving loads were modeled using a linear elastic time history analysis. It was assumed that the rail was connected to the bridge deck at distinct points represented by the rail clip connections at approximately 0.76 m (30 inches) on-center. The magnitude of the axle load at a point ramped up from zero to maximum as the axle traveled from the preceding rail clip to the point under consideration and then decreased to zero as the axle traveled onto the following connection point. This triangular variation with time was modeled as a time dependent ramp function which was applied to the different light rail vehicle trains. The time between the start and end of the ramp function was dependent on the speed of the vehicles and train speed was modeled by changing the time base of the ramp function. Dynamic impact was estimated from the models from the ratio of the maximum deflection at midspan under time dependent moving load to the deflection due to a static load analysis. The results showed that the dynamic impact effects on the structure vary greatly with speed and configuration of the vehicle. While the effects generally increased with vehicle speed, the change was not linear and showed in general more than one peak value within the speed range selected. The maximum computed dynamic effect did not occur at the highest speed. The dynamic effect was also dependent on vehicle configuration, with a clear difference in responses between two axle and three axle cars. The overall length of the vehicle had less of an effect. The results were compared to the impact factors typically used by transit agencies and showed that in general for normal ranges of structure stiffness the Agency criteria are conservative or extremely close for vehicle speeds under 35.3 m/s (79 mph). However, the ACI equation for dynamic impact which is the only equation that incorporates vehicle speed and structural stiffness is usually conservative at higher speeds but may be unconservative at lower and medium speeds and does not reflect effects of axle configuration.

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.

As railroads and local industries served by rail seek to reduce emissions and improve fuel efficiency, new technologies are being developed to serve this market. Contrary to the minimal competitive options available over the last several decades, new companies are now emerging with a variety of locomotive designs aimed at low emissions and low horsepower solutions. Some technologies involve alternative fuels (e.g. natural gas, bio-diesel, battery power, etc.), while others incorporate very low horsepower diesel engines (400hp–1000hp) in order to meet the Tier 4 regulations set by the Environmental Protection Agency (EPA). Yet another option available to railroads and local industries is the mobile railcar mover. Typically used within railroad yard limits or on industry tracks, yard and industrial switchers and mobile railcar movers travel short distances, but must be capable of moving large loads. Subject to high forces when moving cars, these technologies must be both resilient (requiring minimal maintenance) and safe (not subject to derailment or loss of control). As the current market for yard and industrial switchers continues to expand, both railroads and local industries served by rail are placing greater emphases on the environmental and economic benefits of the emerging technologies. This paper aims to analyze the current yard and industrial switcher market and draw conclusions based on emissions data and lifecycle costs. Industrial switchers are compared with yard switchers and mobile railcar movers. Although industrial switchers are more limited in horsepower and operational versatility than yard switchers, many of the daily operations between the two are similar. Mobile railcar movers (e.g. Trackmobile ® and Rail King ® ) offer lower initial costs as well as the versatility of both on-track and off-track movement. However, they may require additional maintenance and offer reduced tractive effort compared to locomotive technologies. As the demands on railroad yard and industry operations grow increasingly complex due to environmental regulations and economic demands, these new technologies have the potential to increase competition in the marketplace and offer improved engineering solutions. By developing a hierarchy of key requirements of yard or industry switchers, this paper provides a framework for identifying the best options available to a railroad or local industries. The scope of this paper will include a review of all options available, but will place a greater emphasis on technologies that are commercially available for wide distribution. By sampling and analyzing the current industrial market, much insight can be gained into daily operational requirements and challenges faced by this sector of the industry.