Improving Casting Integrity Through the Use of Simulation Software and Advanced Inspection Methods

Casting integrity is essential for providing components that meet design criteria for strength and fatigue performance. As the leading method of manufacturing metal components in the rail industry, maintaining quality and consistency is a continuing struggle for car owners and builders. Internal shrinkage and voids due to insufficient metal flow are issues commonly found in casting molds which are not designed or utilized properly. Using casting simulation software, potential issues can be discovered upfront and robust mold designs can be created that offer a tolerance for the variance or variations in casting conditions that are present in the real world. Strato, Inc. has extensively studied the effectiveness of these simulations in foundries through advanced inspection techniques. It is evident that casting simulations can not only locate, but also explain shrinkage cavities and voids through material density plots and inspection of directional solidification via critical fraction solid time plots. This approach is markedly more efficient than the traditional trial and error method, where mold makers rely on experience and destructive testing to develop acceptable mold designs. With recent advances in simulation software, the labor and time-intensive ways of the past have been supplanted by a more scientific approach to the problem. Understanding the fluid dynamics and thermodynamics of the casting process provides a means of creating a stable, repeatable final product. This higher quality final product can be delivered faster to the customer and at a far less expense by identifying problem areas prior to the tooling and sampling processes. Case-studies explored by the Strato engineering team suggest that using this software decreases the fallout rate.

RTCONTACT: An Efficient Wheel-Rail Contact Algorithm for Real-Time Dynamic Simulations

Determination of contact forces exchanged between wheel and rail is one of the most important topics in railway dynamics. Recent studies are oriented to improve the existing contact methods in terms of computational efficiency on one side and on the other side to develop more complex and precise representation of the contact problem. This work shows some new results of the contact code developed at Politecnico di Torino identified as RTCONTACT; this code, which is an improvement of the CONPOL algorithm, is the result of long term activities, early versions were used in conjunction with MBS codes or in Matlab® environment to simulate vehicle behaviour. The code has been improved also using experimental tests performed on a scaled roller-rig. More recently the contact model was improved in order to obtain a higher computational efficiency that is a required for the use inside of a Real Time process. Benefit of a Real Time contact algorithm is the possibility to use complex simulation models in diagnostic or control systems in order to improve their performances. This work shows several comparisons of the RTCONTACT contact code respect commercial codes, standards and benchmark results.

Laser-Based Measurement of Over Dimensional Freight Rail Shipments

In pursuit of improved safety, Norfolk Southern Corp. (NS) has partnered with Amberg Technologies to explore the potential benefits of a laser-based measurement system for measuring over dimensional freight rail shipments. Shipments that do not fall within a standard geometric envelope, denoted as Plate B in the Association of American Railroads (AAR) Open Top Loading Rules [1], are considered to be over dimensional, or High-Wide Loads (HWLs). Extending beyond the limits of the Plate B diagram, these loads are not permitted in unrestricted interchange service. Instead, they must be measured both at points of origin and at interchange points. For US Class I Railroads, the de facto method for measuring HWLs requires mechanical personnel to either climb on the equipment or use a ladder and physically measure the overall height and width of the load. Using a tape measure, plumb line, and 6-foot level, car inspectors, or carmen, must often make multiple measurements to determine the height or width of a critical point on the load. The summation of these measurements can be subject to mathematical human error. In addition to the inherent limitations with regards to accuracy and efficiency, this method of measurement presents considerable safety challenges. The objective of the project was to develop a portable, cost-effective and accurate measurement system to improve the day-to-day operational process of measuring HWLs and reduce human exposure to railyard hazards. Norfolk Southern worked closely with Amberg Technologies to provide a clear overview of the current measuring methods, requirements, challenges and risks associated with HWLs. Amberg then developed a prototype system (with patent pending) and successful tests have been completed at both a point of origin for NS shipments and at a location where HWLs are received at interchange. The measuring system consists of a tripod mounted laser, a specially designed track reference target (TRT) and software designed specifically for HWL measurements. The system allows car inspectors to take measurements from a safe, strategic location away from the car. As a result, this system eliminates the need to climb on the equipment or a ladder and greatly reduces the amount of time spent on and around live tracks. In addition, initial tests indicate that this technology reduces the labor time required to measure HWLs by as much as one half while improving measurement accuracy. These tests have demonstrated that a laser-based system has the potential to greatly improve the safety, efficiency and accuracy associated with measuring HWLs.

Estimation of Track Irregularity Based on Genetic Algorithm and Unscented Kalman Filtering

Track irregularity is the main excitation source of wheel-track interaction. Due to the difference of speed, axle load and suspension parameters between track inspection train and the operating trains, the data acquired from the inspection car cannot completely reflect the real status of track irregularity when the operating trains go through the rail. In this paper, an estimation method of track irregularity is proposed using genetic algorithm and Unscented Kalman Filtering. Firstly, a vehicle-track vertical coupling model is established, in which the high-speed vehicle is assumed as a rigid body with two layers of spring and damping system and the track is viewed as an elastic system with three layers. Then, the static track irregularity is estimated by genetic algorithm using the vibration data of vehicle and dynamic track irregularity which are acquired from the inspection car. And the dynamic responses of vehicle and track can be solved if the static track irregularity is known. So combining with vehicle track coupling model of different operating train, the potential dynamic track irregularity is solved by simulation, which the operating train could goes through. To get a better estimation result, Unscented Kalman Filtering (UKF) algorithm is employed to optimize the dynamic responses of rail using measurement data of vehicle vibration. The simulation results show that the estimated static track irregularity and the vibration responses of vehicle track system can go well with the true value. It can be realized to estimate the real rail status when different trains go through the rail by this method.

Monitoring the Stress Free Temperature of a Complex Segment of Track

A 1.25 km segment of a heavy haul coal line was instrumented with Rail Stress Monitors (RSM) [1–7] and monitored throughout a winter-summer swing in ambient conditions. The track segment included a reverse curve spanning elevated, at-grade, and tunnel conditions that transitioned to a turnout. Natural events along with track maintenance activity punctuated the seasonal shifts in Stress Free Temperature (SFT).

Examining Intercity Rail Passenger Station Access Patterns

Travel on intercity passenger rail is growing in popularity across the U.S. Amtrak, the nation’s intercity passenger rail operator, reported a steady growth in ridership over the last decade; for the 12-month period ending in September 2011, Amtrak carried more than 30 million passengers, a first in the company’s 40-year history. This growth has resulted in widespread interest in developing new intercity passenger rail services or improving existing services with new station facilities and other investments. An issue of interest to the rail planning and policy community revolves around station access patterns, and there are many questions that remain unanswered on this subject. For this paper, these questions include: What is the mode share for passenger trips to and from the rail station? How far do passengers travel to access rail services? Has the market area for intercity passenger rail expanded with increasing ridership, or has the market area remained unchanged during this recent period of growth? Using data obtained from on-board surveys of existing Amtrak passengers in Michigan and Wisconsin, USA, this paper examines the evolving nature of rail passenger station access patterns over the last decade. Specifically, patterns in the overall station access trip mode split, the passengers’ self-reported travel time to and from the rail station, and the spatial distribution of passenger home residential zip codes relative to the rail station are analyzed. Analysis shows that 50 percent of rail passengers reside between 8 and 20 miles from a rail station, depending on the route, and that the market area for selected routes has expanded in recent years. Rail planners can use the findings from this paper to develop new station facility designs or to correct issues that may be present at existing stations. The findings of this paper can also be used to guide the deployment of marketing and promotion of rail services to residents within the “catchment area” of a station.

Driver Behavior Analysis Using Vehicle Safety Systems’ Field Operational Test Data

The United States Department of Transportation’s (US DOT) Research and Innovative Technology Administration’s John A. Volpe National Transportation Systems Center (Volpe Center), under the direction of the US DOT Federal Railroad Administration (FRA) Office of Research and Development (R&D), is leveraging the National Highway Traffic Safety Administration (NHTSA) sponsored Integrated Vehicle Based Safety System (IVBSS) Light Vehicle (LV) Field Operational Test (FOT) to collect and analyze drivers’ activities at or on approach to highway-rail grade crossings. Grade crossings in Michigan, Indiana, and Ohio were cross-referenced with IVBSS LV FOT research vehicle location to identify the time research vehicles were present at a crossing. The IVBSS LV FOT included 108 participants that took a total of 22,656 trips. Of the 22,656 total trips, 3,137 trips included a total of 4,215 grade crossing events. The analysis was based of drivers’ activities at the 4,215 grade crossing events. Both looking behavior and distractions did not significantly differ based on gender. However when analyzed per age-group, younger drivers (between 20 to 30 years old) were significantly more likely to be distracted than middle-aged drivers (between 40 to 50 years old) or older drivers (between 60 to 70 years old). For looking behavior, the data revealed that older drivers are more likely to look at least one way at or on approach to highway-rail crossing (43.8 percent exhibited this behavior) than either middle-aged drivers (35.0 percent exhibited this behavior) or younger drivers (25.3 percent exhibited this behavior).

Design Factors Effecting Capacity of Rail and Transit Systems

The overall impact on system “capacity” is typically described in terms of train control design. There are several other key factors that determine the ultimate system capacity of a rail line. Among the most influential of these are: vehicle type and configuration, stations and platform design and configuration, and overall civil alignment. In the analysis of the maximum capacity delivered from the train control system, all of these require optimization of design to achieve the highest throughput, and have a direct influenced by train control design as well. This paper describes how fully optimized design of non train control issues and factors have an impact on signal system design and have a consequence that is permanent once constructed.

Comparing Geometry Correction Capability of AGGS and TGCS Tamper Control Systems on Amtrak’s Northeast Corridor

One of Amtrak’s high-speed continuous action tampers has been fitted with TGCS (Track Geometry Control System) tamper control software to compare the quality and durability of geometry correction it provides with that of the existing tamper control system, AGGS. Comparison between the two systems is made by reviewing measured track geometry data from before and after maintenance, and by reviewing changes in ride quality accelerations of instrumented passenger cars. Although the testing program is in its early stages and the number of test locations so far is limited, results to date are very much in favor of TGCS.