Vibration Signatures of Temperature Trended Bearings in Field and Laboratory Testing

Over the past two years, a series of papers have been published concerning bearing temperature trending and a mechanism to explain this troubling phenomenon. In September of 2008, a collaborative field test between The Union Pacific Railroad (UP), Amsted Rail, Rail Sciences Inc. (RSI), and The University of Texas-Pan American (UTPA) was conducted to corroborate the findings of laboratory research and testing. Field and laboratory results confirm that temperature trended bearings exhibit vibration signals that can be distinguished from healthy bearings. Distinct primary frequencies and overtones associated with the axle, cone, cage, and rollers can be readily identified within a bearing vibration signal. In a previous paper, it was demonstrated that a trended bearing exhibits vibrations of higher magnitude. However, all characteristic frequencies appear in both healthy and trended bearings, but those that dominate, i.e., have higher magnitude, are distinct for trended bearings when compared to healthy bearings. The latter can be repeatedly demonstrated in both field and laboratory experiments. Moreover, the current work identifies and distinguishes between the primary bearing frequencies and those linked to roller misalignment, which is known to increase friction and wear, and consequently raise the bearing temperature.

Wayside Detection: Component Interactions and Composite Rules

Every day railcars are setout for repair based on wayside detector absolute alarm limits. These alarms successfully identify most of the cars capable of causing derailments. There would be thousands of additional cars set out if these absolute alarms were lowered to the levels required to remediate the remaining cars capable of causing derailments. The rail industry cannot tolerate this level of setouts, nor can it tolerate derailments. A more focused approach is required. BNSF has developed a Composite Rules Engine (CRE), which combines and evaluates the data currently gathered by each individual wayside detection system. It is capable of pin-pointing the worst of the worst among the remaining cars exhibiting elevated detector readings. CRE provides BNSF the means of bridging its stand alone detection systems to provide one centralized alarming system. The CRE is able to combine the separate rule flows of: Acoustic Bearing Detectors (ABD), Machine Vision Systems (MVS), Truck Hunting Detectors (THD), Truck Performance Detectors (TPD), Hot Bearing Detectors (HBD), a Warm Bearing Detection System (WBDS), Hot / Cold Wheel Detectors (HW) and Wheel Impact Load Detectors (WILD). In summary, CRE targets cars with multiple low level indications that, individually, are of little concern, but collectively have the potential to cause derailments.

Mathematical Justification of the New Method of Determination of Wheel Pair’s and Rail’s Damage

Development of modern railways largely depends on the control of intactness of the wheel pairs and rails. It is impossible to ensure safety and increase the speed of railway traffic without providing such control. Detection of the wheel pairs’ and rails’ wear and damage is one of the key problems of railway science. Many scientific works are accomplished and lot of devices are elaborated in this field, but the mentioned problem still remains urgent. In order to increase the traffic safety, the group of authors has proposed a constructional scheme of the mobile device for detection of wheel pairs’ and rails’ wear and damage, which will have increased accuracy of measurement. Increasing of accuracy of measurement is carried out on the basis of development of mathematical model, which provides the realization of equal wear of wheel pairs’ as well as ones no equal wear. By installation of the proposed device on each wheel pair of each railcar of the rolling stock, the automatic control of wheel pairs’ and rails’ condition will be achieved. Namely: -Detection of the worn out wheel pair and determination of wear degree; -Detection of the damaged wheel pair; -Identification of the worn out or damaged wheel pair. Besides, on the basis of elaborated mathematical model: -Detection of the worn out rail; -Detection of the damaged rail; -Identification of location of the worn out or damaged rail. The obtained information will be constantly connected to the locomotive computer system. Therefore, for checking rolling stocks, there will no longer be need to build expensive stationary systems, to move trains great distances for their inspection and in the result, the time lost for stoppage will be saved. So, with the help of proposed mobile device, the traffic safety increases and at the same time expenses for detection of wheel pairs’ wear and damage decrease, which results in significant economic effect.

Automated Structural Health Monitoring of Bolted Joints in Railroad Switches

Current switch bolt inspection on rail systems is a labor intensive and sometimes unreliable approach to maintaining the switch integrity. Recent rail accidents in the United Kingdom (Potters Bar in 2002 and Grayrigg in 2007) underscore the need for routine inspections of the switch mechanisms. From the Grayrigg report of 23 February 2007 the main causes of the accident were found to be the loosening and, as a result, the initiation and growth of cracks, and, eventually, rupture of the bolts of the switch bars, especially the one maintaining the switch rails at a correct distance apart. Such findings also resulted from the 2002 crash report but unfortunately frequent visual inspections were not forthcoming. In this paper, an effective method for monitoring the loosening of the switch bolts is described. As the loosening of the bolts further causes the crack formation in the bolted joints, it seems valid to say that the early detection of loosening of bolted joints in railroad switches will be of great importance in eliminating the need for frequent visual inspection by totally automating inspection of the switches’ mechanical condition. The first part of the present paper focuses on the use of smart materials and structures for the health monitoring of bolted joints in railroad switches. It is shown that using the piezoelectric transducers and the impedance-based structural health monitoring technique, the loosening of the bolted joints are detectable. The accuracy in loosening detection is as high as 25 ft-lbs which corresponds to merely 1/10th of a bolt turn. Being able to detect the loosening of the bolted joints in railroad switches, the concept of self-healing bolted joints is applied in the next part in order to automatically retighten the loosened bolts to their prescribed functional conditions.

Strategy for Alternative Occupant Volume Testing

This paper describes plans for a series of quasi-static compression tests of rail passenger equipment. These tests are designed to evaluate the strength of the occupant volume under static loading conditions. The research plan includes a detailed examination of the behavior of conventional equipment during the 800,000-pound buff strength test. The research will also include a demonstration of an alternative static test that is designed to load and test the occupant volume at a location other than the buff lugs. The alternative test will demonstrate a testing and evaluation method for the occupant volume strength of passenger rail cars that accounts for the collision load path through the occupant volume. Per current Federal Railroad Administration (FRA) regulations, all passenger cars must support an 800,000-pound static load applied to the car’s line of draft without undergoing permanent deformation. However, more operators are looking to introduce equipment built to foreign standards. Many international manufacturers are implementing alternative designs that make use of crash energy management design features, articulated truck designs that span two cars, and low floor designs. These changes in the form and function of the designs require alternative means of applying a compressive load to assess occupant volume strength. FRA has reviewed several proposed alternatively designed equipment under requests for waivers for specific corridors of operation. Because the number of requests has increased significantly, FRA is trying to establish reasonable alternative means for assessing adequate and equivalent occupant volume strength to conventional equipment. This paper proposes an alternative static test procedure that will provide a means of evaluating a similar level of occupant volume integrity and passenger protection during a collision. The test will allow for greater design variation for newer rail cars and cars built to foreign standards. For the alternative test, the load may be introduced through the available structure at the floor level and at the roof level. These loading locations will enable the load to be applied directly into key longitudinal members in the load path of collision loads through the occupant volume. Finite element models are used before testing to determine appropriate alternative load levels and locations. The test article is a modified Budd Pioneer car. No significant modifications are planned for the longitudinal members of the car, or for the occupant volume.

Fuzzy Analysis of Speech Metrics to Estimate Conductor Alertness

A Fuzzy Logic-based algorithm has been developed for processing a series of speech metrics with the ultimate goal of estimating train conductor alertness. The output is a single metric, which directly quantifies the alertness level of the conductor. The metrics were selected based on their correlation to alertness through processed speech, but without any interpretation of the spoken words or phrases. Metrics that are used include: speech duration, silence duration, word production rate and word intensity. The assessment of these metrics is an experience and human knowledge based task, which generates the need for a mathematical model to accommodate this special circumstance. The algorithm developed here uses Fuzzy Logic to cast the human knowledge base into a mathematical framework for the alertness estimation analysis. The core of this fuzzy system is a rule base consisting of fuzzy IF-THEN rules, which are derived from the existing knowledge about the effects of sleep deprivation on alertness such as Furthermore, the rules were inferred from actual voice recordings that were taken on board a train. This data was then used to create a classification scheme to determine which pattern in the speech indicates different levels of alertness from anxiety to fatigue. The simplicity of the underlying mathematical model in this approach enables this system to compute and output an alertness metric in real-time. The nature of this algorithm allows for the use of an arbitrary number of rules to classify the alertness level and therefore provides the ability to continuously develop and extend the rule base as new knowledge emerges. The resulting algorithm is a fast, multi-input, single-output system that is able to quantify the train conductor’s alertness level anytime speech is produced.

Brake Shoe Force Variation

The Wheel Defect Prevention Research Consortium (WDPRC) has conducted a review and analysis of existing literature and existing data related to brake shoe force (BSF) variation in freight car brake rigging. This work was conducted to explore the sources of BSF variation, define the expected amount of BSF variation, and describe some of the existing brake system designs that may help reduce the amount of BSF variation. Wheel temperature is related to BSF due to the use of the wheel tread as a brake drum. Variation in BSF within a given railcar is one potential source of elevated wheel temperatures and thermal mechanical shelling (TMS) damage to the wheels. At elevated temperatures, wheels become less resistant to fatigue damage due to changes in the material mechanical properties and relief of beneficial residual stresses. Data recorded by a wayside wheel temperature detector shows that eliminating wheel temperature differences within individual cars could reduce the number of wheels reaching temperatures of concern for TMS by a factor of eight.

Improving Punctuality of Train Traffic on Western Main Line of Swedish Railway Network: Simulation Approach

Western main line is one of the most important railway lines in Sweden. The line section from Stockholm to Katrineholm, which connects the largest cities of the Sweden i.e. Stockholm, Gothenburg and Malmo¨, is studied. This line has heterogeneous train traffic consisting high-speed, regional, freight and commuter trains. This paper attempts to study different factors affecting punctuality on this railway line concentrating on traffic problem around Gnesta station and commuter train turn-back scenario — a bottleneck — at the same station. Simulation of existing and modified timetable is done using train traffic simulation software “Railsys”. Experiments including examining effect of rescheduling train timings, capacity enhancement and infrastructure changes in rail network are conducted and investigated. Robustness analysis is performed from the results of simulation and investigation of the consequences of delays and comparison of how different features in the timetables affect the robustness is done.

Detailed Impact Analyses for Development of the Next Generation Rail Tank Car: Part 2—Development of Advanced Tank Car Protection Concepts

Significant research has been conducted over the past few years to develop improved railroad tank cars that maintain tank integrity for more severe accident conditions than current equipment. The approach taken in performing this research is to define critical collision conditions, evaluate the behavior of current design equipment in these scenarios, and develop alternative strategies for increasing the puncture resistance. The evaluations are being performed with finite element models of the tank cars incorporating a high level of detail. Both laboratory scale and full-scale impact tests were performed to validate the modeling and ultimately compare the effectiveness of current and alternative equipment designs. This paper describes the use of the detailed finite element impact and puncture analyses to assess the performance of advanced puncture protection concepts.

Detailed Impact Analyses for Development of the Next Generation Rail Tank Car: Part 1—Model Development and Assessment of Existing Tank Car Designs

Significant research has been conducted over the past few years to develop improved railroad tank cars that maintain tank integrity for more severe accident conditions than current equipment. The approach taken in performing this research is to define critical collision conditions, evaluate the behavior of current design equipment in these scenarios, and develop alternative strategies for increasing the puncture resistance. The evaluations are being performed with finite element models of the tank cars incorporating a high level of detail. Both laboratory scale and full-scale impact tests were performed to validate the modeling and ultimately compare the effectiveness of current and alternative equipment designs. This paper describes the development of the detailed finite element model of the tank car and the use of the model for impact and puncture analyses. The validation of the model using the results of the full-scale impact tests is presented. The subsequent application of the model to assess the puncture resistance of existing tank car designs is discussed.