This paper provides an update to the 2015 paper titled “A New Energy Storage Substation for the Portland to Milwaukie Light Rail (PMLR) Extension” [4] presented at the 2015 JRC in San Jose. The energy storage substation (ESS) with super-capacitor technology manufactured by Siemens was installed in place of a utility-connected substation at the Tacoma substation location to capture the energy generated by braking light rail vehicles and store it in the ESS energy savings mode and feed it back to the traction power supply during vehicle acceleration. In voltage stabilization mode, the ESS will enable the rail system to maintain voltage system stability by ensuring the system voltage to remain within the required voltage ranges and prevent system disruptions due to low system voltage conditions. In the Fall 2015, the Tacoma ESS went into service as part of the PMLR Orange Line light rail extension. This paper presents the design concepts for the unit, briefly discusses installation and testing, and focuses on the optimization process, operating experience, energy savings and reliability. TriMet operates a fleet of 145 light rail vehicles on its 60 mile network. Approximately 75% of the energy regenerated during braking is captured and re-used, saving an estimated $1.8 M annually in energy cost. The Tacoma ESS capacity is approximately 2.5 kWh. The unit normally operates in energy savings mode, maximizing recovery and re-use of braking energy while the secondary voltage stabilization mode is available to maintain system operation during outage conditions. After more than two years of revenue service operation, detailed operating data is presented and analyzed, including reliability information and actual energy and cost savings.

While timber crossties are widely used in North America, the popularity of concrete crossties has increased significantly in recent years. Concrete crossties require the use of premium elastic fastening systems to have a proper and stable system. The primary role of fastening system is to attach the rail to its support preserving track geometry. For this reason, past research has focused on its development and behavior. Even though a large amount of research has been conducted on heavy-haul freight railroad systems, little work has been conducted to focus on rail transit systems. Therefore, a field analysis of the behavior of fastening systems under rail transit system loading conditions has been executed, focusing on light rail transit loading conditions. To perform this study, revenue service field data were collected on a light rail transit system. The instrumentation used and how it was installed on site are described in this paper. The critical quantitative metric discussed in this study is the relative displacement of the rail with respect to the concrete crosstie. Analyzing vertical and horizontal displacements, as well as rotation, the performance of the fastening system can be evaluated. For this purpose, different sites on the same rail system were selected for study, comparing both curve and tangent track geometry. In addition to this, the movement of the rail under every axle of the light rail vehicle has been studied in detail. In summary, an analysis of how the rail performs in terms of displacement under light rail transit loading conditions has been completed. Based on field data, the analysis allows the reader to understand how the rail displaces under the given loads when it is installed in a ballasted concrete crosstie track and restrained by elastic fastening systems.

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.

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.

The $1.4 billion Portland-Milwaukie Light Rail (PMLR) Extension Project includes a light rail alignment that travels 7.3 miles, connecting Portland State University in downtown Portland, inner Southeast Portland, Milwaukie and North Clackamas County. Revenue service on the alignment is scheduled to begin in September 2015. An energy storage substation (ESS) with super-capacitor technology manufactured by Siemens is being installed in place of a utility-connected substation at the Tacoma substation location to capture the energy generated by braking light rail vehicles and store it in energy savings mode, feeding it back to the traction power supply during vehicle acceleration. In voltage stabilization mode, the ESS will enable the rail system to maintain voltage system stability by ensuring the system voltage to remain within the required voltage ranges and prevent system disruptions due to low system voltage conditions. This paper will discuss the features of the 677KW 2.5KWH Tacoma ESS including super-capacitor based energy storage system technology, ESS equipment arrangement, protection and controls. Economic benefits of cost savings in energy (KWH) consumption and power demand (KW) charges will also be discussed. Field accepting test plans and test procedures will also be presented.

The design development and analysis of a novel Light Rail Vehicle (LRV) end-mounted bumper concept is described. The purpose of the bumper is to improve crash compatibility of LRVs with shared right of way road vehicle traffic. Under a grant from the Transportation Research Board (TRB) Transit IDEA program, the present project builds on previous Transit Cooperative Research Program (TCRP) and Federal Transit Administration (FTA) sponsored work by adapting a generic conceptual retrofit bumper design onto the CAF LRV currently in service with Sacramento Regional Transit (RT). The bumper system is designed to reduce the severity of collisions and to reduce injuries for passengers in the struck vehicles. The reusable bumper is also designed to survive common collision scenarios, thereby minimizing service interruptions and downtime. The adapted design takes into account the geometry, necessary clearances, and other requirements of the RT CAF LRV while also incorporating the lessons learned from the original bumper concept optimization. Detailed nonlinear finite element crash analysis was used to evaluate the adapted design for a suite of common collision scenarios. The efficacy of the bumper system was evaluated through struck vehicle occupant injury assessments. The analysis has shown significantly improved crash performance for the adapted bumper system compared to the current LRV configuration without a bumper. Ongoing effort and future plans in pursuit of fielding the system are discussed.

This article will propose different energy storage systems, ranging from 0.91 kWh to 1.56 kWh, suitable for a 30 m long tram. To configure the system regarding energy content, voltage variation, maximum current and power losses, a model of the tram, network and substations power flow has been developed in a Matlab/Simulink environment. Results obtained in energy savings at substation level vary from 24% to 27, 6% under the same driving profile and auxiliaries load; while at the end-of-life of supercapacitors, the range varies from 18, 1% to 25, 1% depending on the supercapacitor module used and vehicle load.

Rail vehicle safety standards for the United States have historically placed emphasis on static structural strength requirements to ensure safety. The primary requirements to ensure crash safety of light rail vehicles were static load cases including car body buff loads, collision post loads, corner post loads, etc. More recent developments for light rail vehicles in the United States have included crash energy management design methodologies. This is consistent with the trend in other modes of transportation applying modern crashworthiness engineering. The challenges of incorporating crash energy management into light rail vehicles are the lack of crashworthiness standards for the light rail industry, the introduction of new design methodologies, and the concerns of compatibility of new and older equipment. This issue of compatibility in vehicle designs would often inhibit introduction of innovations and potential safety improvements within an existing light rail transit system. However, there are ongoing efforts to address each of these challenges. The American Society of Mechanical Engineers has a committee working on the development of a new safety standard for light rail vehicles. Light rail vehicle manufacturers are increasingly using modern crashworthiness design principles. In addition, modern crash analysis methodologies allow for the assessment of vehicle incompatibilities in the design process. In this paper, the developments of crash energy management strategies in the light rail industry are discussed. These include the ongoing standards development efforts and the application of crash energy management principles in recent light rail vehicle design efforts. Examples will be provided for the use of crash analyses in a vehicle design. The interaction of the crash and static analyses will be discussed and examples of both compatible and incompatible collision scenarios will be presented.

The basic standard US LRV structural designs are virtually unchanged from those adopted 25 years ago based on a modified European subway car. With only one exception, these have not been significantly updated for or adapted to the high levels of in-street running found more and more on new light rail systems or for increased passenger safety in general. Today in Europe, the overall structural design approach for LRVs is to absorb initial collision energy without any structural damage. To evaluate this approach, the four most common vehicle collision scenarios are first identified and quantified. Then European operational experience, particularly as regards accidents, is presented and analyzed. From these, we can see that further improvements to US rail vehicle design safety, especially to interior spaces, are both overdue and inevitable. Recent US LRV structural safety standard developments are considered and recommendations are proposed for incorporation into new light rail vehicle designs.

The use of electronic subsystems to perform complex tasks has grown in the consumer goods and automotive sectors to such a degree that these capabilities have become commonplace, yet in the field of light rail vehicles, they have made relatively little impact. The technology exists today to provide greatly increased passenger safety, security and system operational efficiency by the judicious application of mature subsystem designs. Such systems include radio based, fully integrated vehicle management systems with GPS, silent alarm capability and passenger information control, external passenger door and coupler monitoring video cameras, forward facing video recording for accident investigations, interior video recording for reduction in vandalism, interior video cameras linked to Passenger to Operator Intercoms to provide the Operator with more information and the transfer of data to and from vehicles via wireless LAN. This paper will describe the application of these subsystems to the new Phoenix light rail vehicle and project what the future may hold.

New electrically propelled passenger trains use AC propulsion with induction traction motors and variable voltage, variable frequency drives. Benefits include higher performance, reduced starting energy use, regenerated braking energy, lower maintenance, and a broadened range of operating conditions. However, some Transit Operators have found that new trains have not fully delivered the economic benefits of regeneration. An effective Energy Storage System (ESS) can capture the full energy savings benefit of regenerative braking and will reduce the peak power usage which incurs high peak power demand charges. Candidate ESS technologies include flywheels, supercapacitors, and batteries. This paper provides a set of typical requirements for a transit wayside ESS, and evaluates the strengths and weaknesses of the candidate technologies against the requirements. Primary ESS benefits are energy savings and peak power reduction. The authors calculated potential savings for a generic ESS at two typical transit systems: a dense US heavy rail system with 10-car trains, and a US light rail line that runs trains of two to four Light Rail Vehicles (LRVs). In the heavy rail case study, a properly sized ESS will provide energy savings of up to 4.4 kWH per train start/run/stop cycle. This is a savings of 3.6 MWH per day per ESS, or 21% of the total energy. In the light rail case study, ESS will reduce the peak power demand by up to 119 kWH/H, or 23% of the total peak demand.

In recent years extensive effort has been devoted to the development of crashworthiness standards for rail cars spanning modalities from light rail to heavy rail and commuter rail applications. Each mode provides different challenges to the designer, whether it is designing against collisions with similar rail car designs, dissimilar vehicle designs such as freight rail vehicles or other obstructions such as pedestrians and street running automobiles. Structural standards in the U.S. and internationally are being developed to address these modes and provide a sensible approach to occupant protection [1, 2]. The advent of crash energy management (CEM) science as a means for better controlling the energy in a collision is being applied universally in rail car applications, yet there is variability on CEM design approaches to account for the variability in obstructions. This paper focuses on the development of CEM design for light rail vehicles in the U.S. based on efforts of the ASME Rail Transit Vehicle Standards Committee. A comparison is made between current LRV standardization efforts and recent commuter rail specifications that include CEM.