David Tyrell

Train-to-Train Impact Test of Crash-Energy Management Passenger Rail Equipment: Structural Results

On March 23, 2006, a full-scale test was conducted on a passenger rail train retrofitted with newly developed cab and coach car crush zone designs. This test was conducted as part of a larger testing program to establish the degree of enhanced performance of alternative design strategies for passenger rail crashworthiness. The alternative design strategy is referred to as Crash Energy Management (CEM), where the collision energy is absorbed in defined unoccupied locations throughout the train in a controlled progressive manner. By controlling the deformations at critical locations, the CEM train is able to protect against two very dangerous modes of deformation: override and large scale lateral buckling. Frames from high-speed movies recorded at the train-to-train test of existing equipment and the train-to-train test of CEM equipment are included in this paper. In the train-to-train test of existing equipment at a closing speed of 30 mph, the colliding cab car crushed by approximately 22 feet. No crush was imparted to any of the trailing equipment. Due to the crippling of the cab car structure, the cab car overrode the conventional locomotive. The space for the operator’s seat and for approximately 47 passenger seats was lost. During the train-to-train test of CEM equipment, at a closing speed of 31 mph, the front of the cab car crushed by approximately 3 feet, and the crush propagated back to all of the unoccupied ends of the trailing passenger cars. The controlled deformation of the cab car prevented override. All of the crew and passenger space was preserved.

Impact tests of crash energy management passenger rail cars: analysis and structural measurements

Two full-scale impact tests were conducted to measure the crashworthiness performance of Crash Energy Management (CEM) passenger rail cars. On December 3, 2003 a single car impacted a fixed barrier at approximately 35 mph and on February 26, 2004, two-coupled passenger cars impacted a fixed barrier at approximately 29 mph. Coach cars retrofitted with CEM end structures, which are designed to crush in a controlled manner were used in the test. These test vehicles were instrumented with accelerometers, string potentiometers, and strain gages to measure the gross motions of each car body in three dimensions, the deformation of specific structural components, and the force-crush characteristic of the CEM end structure. Collision dynamics models were developed to predict the gross motions of the test vehicle. Crush estimates as a function of test speed were used to guide test conditions. This paper describes the results of the CEM single-car and two-car tests and provides results of the structural test. The single-car test demonstrated that the CEM design successfully prevented intrusion into the occupied volume, under similar conditions as the conventional test. During both CEM tests, the leading passenger car crushed approximately three feet, preserving the occupant compartment. In the two-car test, energy dissipation was transferred to the coupled interface, with crush totaling two feet between the two CEM end structures. The pushback of the couplers kept the cars in-line, limiting the vertical and lateral accelerations. In both the conventional tests there was intrusion into the occupant compartment. In the conventional two-car test sawtooth lateral buckling occurred at the coupled connection. Overall, the test results and model show close agreement of the gross motions. The measurements made from both tests demonstrate that the CEM design has improved crashworthiness performance over the conventional design.© 2004 ASME

Locomotive crashworthiness design modifications study

A study has been conducted of locomotive crashworthiness in a range of collision scenarios to support the efforts of the Locomotive Crashworthiness Working Group of the Federal Railroad Administrations Railroad Safety Advisory Committee (RSAC) to develop locomotive crashworthiness requirements. The RSAC is a government/industry committee including all segments of the rail community, with the purpose of developing solutions to safety regulatory issues. This paper presents the results of a study of the crashworthiness of conventional and modified locomotive designs in five collision scenarios.

The development of a rail passenger coach car crush zone

This paper presents information on the design of a rail vehicle crush zone for better occupant protection. The overall design requirements and characteristics are described and the configuration for the various structural subsystems is presented. The paper also includes information on full-scale component tests carried out to support the development of the design, particularly for the primary energy absorbers. Comparisons between test and finite element analysis are presented and there is a discussion of how the test results have affected the design.

Impact test of a crash-energy management passenger rail car

On December 3, 2003, a single-car impact test was conducted to assess the crashworthiness performance of a modified passenger rail car. A coach car retrofitted with a crash energy management (CEM) end structure impacted a fixed barrier at approximately 35 mph. This speed is just beyond the capabilities of current equipment to protect the occupants. The test vehicle was instrumented with accelerometers, string potentiometers, and strain gages to measure the gross motions of the car body in three dimensions, the deformation of specific structural components, and the force/crush characteristic of the impacted end of the vehicle. The CEM crush zone is characterized by three structural components: a pushback coupler, a sliding sill (triggering the primary energy absorbers), and roof absorbers. These structural mechanisms guide the impact load and consequent crush through the end structure in a prescribed sequence. Pre-test activities included quasi-static and dynamic component testing, development of finite element and collision dynamics models and quasi-static strength tests of the end frame. These tests helped verify the predicted structural deformation of each component, estimate a force-crush curve for the crush zone, predict the gross motions of the car body, and determine instrumentation and test conditions for the impact test. During the test, the passenger car sustained approximately three feet of crush. In contrast to the test of the conventional passenger equipment, the crush imparted on the CEM vehicle did not intrude into the passenger compartment. However, as anticipated the car experienced higher accelerations than the conventional passenger car. Overall, the test results for the gross motions of the car are in close agreement. The measurements made from both tests show that the CEM design has improved crashworthiness performance over the conventional design. A two-car test is performed to study the coupled interaction of CEM vehicles as well as the occupant environment. The train-to-train test results are expected to show that the crush is passed sequentially down the interfaces of the cars, consequently preserving occupant volume.

Evaluation of Rail Passenger Equipment Crashworthiness Strategies

Comparisons are made of the effectiveness of competing crashworthiness strategies—crash energy management (CEM) and conventional passenger train design. CEM is a strategy for providing rail equipment crashworthiness that uses crush zones at the ends of cars. These zones are designed to collapse in a controlled way during a collision, distributing the crush among the train cars. This technique preserves the occupied spaces in the train and limits the decelerations of the occupant volumes. Two scenarios are used to evaluate the effectiveness of the crashworthiness strategies—(a) a train-to-train collision of a cab-car–led passenger train with a standing locomotive–led passenger train and (b) a grade-crossing collision of a cab-car-led passenger train with a standing highway vehicle. The maximum speed for which all the occupants are expected to survive and the predicted increase in fatalities and injuries with increasing collision speed are determined for both train designs. Crash energy management is shown to significantly increase the maximum speed at which all the occupants could survive for both grade crossing and train-to-train collisions for cab-car–led trains, at the expense of modestly increasing the speeds at which occupants impact the interior in train-to-train collisions.

Evaluation of cab car crashworthiness design modifications

A study was conducted to evaluate the effectiveness of structural modifications to rail cab cars for increased crashworthiness protection in train collisions. The crashworthiness benefits were calculated based on a particular designs ability to preserve the space occupied by the operators and the passengers during a collision. The influences of the modifications on vehicle weight and cost to manufacture were also estimated. The focus of the study was a collision scenario in which a cab car-led consist traversing a switch onto mainline track obliquely collides with a locomotive-led consist traveling in the opposing direction on the mainline track. Modifying the strength of the end-structure members up to the load limits implied by the support structures-800000 pounds-increases the collision speed at which all the occupants are expected to survive to /spl sim/20 mph from /spl sim/10 MPH for the baseline design. Within the allowable spaces of the baseline design, potential modifications have been developed which increase the end beam strength to nearly three times the baseline design strength, and increase the side sill strength to 11/4 times the baseline strength. Such design modifications, along with commensurate corner post and door post designs, made to the leading end of the cab car would add 670 lbs (/spl sim/0.7%) to the weight of the cab car and about

Crashworthiness analysis of the Placentia, CA rail collision

2000 (/spl sim/0.1%) to the purchase price.

Development of Crash Energy Management Designs for Existing Passenger Rail Vehicles

Abstract The Volpe Center is supporting the Federal Railroad Administration in performing rail passenger equipment crashworthiness research. The overall objective of this research is to develop strategies for improving structural crashworthiness and occupant protection. A field study of passenger train accidents is being conducted to investigate the causal mechanisms of how train occupants are injured during accidents. The investigation of the April 23, 2002 collision in Placentia, CA is being used to develop occupant protection strategies. This process first required the development of two simulation models: a collision dynamics model and an occupant response model. These models suggested that workstation tables brought about fatal thoracic and abdominal injuries in two occupants. Improved crashworthiness performance workstation tables, which limit the abdominal load imparted by the table, are currently under investigation through modelling and full-scale testing with advanced anthropomorphic test devices.

Rail-car impact tests with steel coil: car crush

As part of the passenger equipment crashworthiness research, sponsored by the Federal Railroad Administration and supported by the Volpe Center, passenger coach and cab cars have been tested in inline collision conditions. The purpose of these tests was to establish baseline levels of crashworthiness performance for the conventional equipment and demonstrate the minimum achievable levels of enhancement using performance based alternatives. The alternative strategy pursued is the application of the crash energy management design philosophy. The goal is to provide a survivable volume where no intrusion occurs so that passengers can safely ride out the collision or derailment. In addition, lateral buckling and override modes of deformation are prevented from occurring. This behavior is contrasted with that observed from both full scale tests recently conducted and historical accidents where both lateral buckling and/or override occurs for conventionally designed equipment. A prototype crash energy management coach car design has been developed and successfully tested in two full-scale tests. The design showed significant improvements over the conventional equipment similarly tested. The prototype design had to meet several key requirements including: it had to fit within the same operational volume of a conventional car, it had to be retrofitted onto a previously used car, and it had to be able to absorb a prescribed amount of energy within a maximum allowable crush distance. To achieve the last requirement, the shape of the force crush characteristic had to have tiered force plateaus over prescribed crush distances to allow for crush to be passed back from one crush zone to another. The distribution of crush along the consist length allows for significantly higher controlled energy absorption which results in higher safe closing speeds.Copyright