2013 Session: 502

• Optimal Clustering of Railroad Track Maintenance Jobs
  Abstract: Freight railroads in North America spend billions of dollars every year on track maintenance. Track maintenance activities not only incur high capital costs, but also have a significant impact on railroad safety and operational efficiency. Job clustering is an important part of railroad track maintenance planning. It focuses on clustering track maintenance jobs into projects, so that the projects can be assigned to the production teams and scheduled in the planning horizon. The real world instances of job clustering problem usually have a very large scale, involving thousands of jobs per year. Various difficult side constraints such as mutual exclusion constraints and rounding constraints further increase the difficulty in solving the problem. Therefore, the railroad mainly relies on the experience and knowledge of experts to solve this problem manually. In this paper, we develop a mixed-integer mathematical programming model in the form of vehicle routing problem with side constraints, and propose a set of integrated heuristic algorithms to solve the problem. The proposed model and algorithms have been adopted by a Class-I railroad to help their practical operations for a few years.
  Authors: Peng, Fan; Ouyang, Yanfeng
  Authors: Peng, Fan; Ouyang, Yanfeng
  Year: 2013
  Document Type: Paper
  Subject: Railroads; Rail
  Session: 502
  Paper Number: 13-0793
• RAIL-NT System for In Situ Measurement of Neutral Temperature in Continuous-Welded Rail: Results from Laboratory and Field Tests
  Abstract:

  The University of California at San Diego (UCSD), under a Federal Railroad Administration (FRA) Office of Research and Development (R&D) grant, is conducting research to develop a system for in-situ measurement of stress in Continuous-Welded Rail (CWR) for use as a basis for the determination of Neutral Temperature (NT). It is known that CWR can break in cold weather and can buckle in hot weather due to thermally induced stresses. The need for a reliable technique for NT (rail temperature with zero thermal stress) determination has been an on-going challenge for the railroads since the advent of CWR more than forty years ago. The railroads need to know the level of stress in the rail to properly schedule slow-order mandates and prevent derailments. UCSD has developed a prototype (Rail-NT) for wayside rail NT measurement that is based on non-linear ultrasonic guided waves. Numerical models were first developed to identify optimum guided wave modes and frequencies for maximum sensitivity to the thermal stresses in the rail web, with minimal influence of the rail head and rail foot. Experiments conducted at the UCSD Large-scale Rail NT Test-bed indicated a rail NT measurement accuracy of a few degrees. The first field tests of the Rail-NT prototype were performed in June 2012 at the Transportation Technology Center (TTC) in Pueblo, CO in collaboration with the Burlington Northern Santa Fe (BNSF) Railroad. The results of these field tests were very encouraging, indicating an accuracy for NT measurement of 5 °F at worst, on both wood and concrete ties. One of the issues that remain to be investigated is the effect of passing trains on the rail NT measurements.

  Authors: Nucera, Claudio; Phillips, Robert; Lanza di Scalea, Francesco; Fateh, Mahmood; Carr, Gary
  Authors: Nucera, Claudio; Phillips, Robert; Lanza di Scalea, Francesco; Fateh, Mahmood; Carr, Gary
  Year: 2013
  Document Type: Paper
  Subject: Railroads; Rail
  Session: 502
  Paper Number: 13-3511
• Ultrasonic Tomography for Three-Dimensional Imaging of Internal Rail Flaws: Proof-of-Principle Numerical Simulations
  Abstract:

  This paper describes proof-of-principle numerical simulations that demonstrate the technology of Ultrasonic Tomography for 3-D imaging of internal rail flaws. There is a need to develop new technologies that are able to quantify the internal rail flaws so as to ensure increased safety of rail transportation and reduced rail maintenance costs. In this work, the technique of Ultrasonic Tomography was applied to the detection of a 5% H.A. Transverse Defect in the railhead. Finite Element models of ultrasonic tomographic arrays on a flawed rail were built, followed by an algorithm designed to perform the tomographic imaging of the internal rail flaw in 3-D and automatically. The results show excellent 3-D imaging performance. The work confirms the potential of the Ultrasonic Tomography technique for the quantitative verification of internal rail flaws.

  Authors: Lanza di Scalea, Francesco; Rizzo, Piervincenzo; Salamone, Salvatore; Bartoli, Ivan; Al-Nazer, Leith
  Authors: Lanza di Scalea, Francesco; Rizzo, Piervincenzo; Salamone, Salvatore; Bartoli, Ivan; Al-Nazer, Leith
  Year: 2013
  Document Type: Paper
  Subject: Railroads; Rail
  Session: 502
  Paper Number: 13-3975
• Measuring Concrete Cross-Tie Rail Seat Pressure Distribution with Matrix-Based Tactile Surface Sensors
  Abstract: A sustained increase in gross rail loads and cumulative freight tonnages, as well as growing interest in high speed passenger rail development, is placing an increasing demand on North American railway infrastructure. To meet this demand, concrete crossties will require increased strength and durability. One of the typical failure modes for concrete crossties in North America is Rail Seat Deterioration (RSD), and researchers have hypothesized that localized crushing of the concrete in the rail seat is one of the potential mechanisms that contributes to RSD. To better understand this mechanism, the University of Illinois at Urbana-Champaign (UIUC) is utilizing a matrix based tactile surface sensor (MBTSS) to measure and quantify the forces and pressure distribution acting at the contact interface between the concrete rail seat and the bottom of the rail pad. Preliminary data collected during laboratory testing has shown that a direct relationship exists between rail pad modulus (stiffness) and maximum rail seat pressure. A direct relationship between the lateral/vertical (L/V) force ratio and the maximum field side rail seat pressure has also been observed. Given that all preliminary results indicate that various combinations of pad stiffness, track geometry, and L/V ratios create localized areas of high pressure, crushing remains a potential mechanism leading to RSD, as will be discussed in this paper. Through the analysis of rail seat pressure data, valuable insight will be gained that can be applied to the development of concrete crosstie and fastening system component designs that meet current and projected service demands.
  Authors: Rapp, Christopher Thomas; Dersch, Marcus S.; Edwards, J. Riley; Barkan, Christopher P. L.; Wilson, Brent; Mediavilla, Jose
  Authors: Rapp, Christopher Thomas; Dersch, Marcus S.; Edwards, J. Riley; Barkan, Christopher P. L.; Wilson, Brent; Mediavilla, Jose
  Year: 2013
  Document Type: Paper
  Subject: Railroads; Rail
  Session: 502
  Paper Number: 13-4908
• Railway Track Geometry Defect Modeling: Deterioration, Derailment Risk, and Optimal Repair
  Abstract: Analyzing track geometry defects is critical for safe and effective railway transportation. Repairing the right number and type of track geo-defects can appropriately reduce the probability of derailments. Additionally, prioritized track geometry repair work reduces dynamic vehicle and track interaction, thus reducing the stress state of the railroad. In this paper, we propose an analytical framework for making optimal geo-defect repair decisions by minimizing total expected costs, which include potential derailment costs and repair costs. Our major contribution lies in formulating and integrating the following three data-driven models: 1). A track deterioration model to study the degradation of Class II geo-defects; 2). A survival model to assess the derailment risk as a function of the track condition; 3). An optimization model under uncertainty for track repair decisions. In real-world examples, compared with heuristic strategies in practice, our proposed models can reduce 20% of the total composite cost on average, and potentially even more for long track sections.
  Authors: He, Qing; Li, Hongfei; Bhattacharjya, Debarun; Parikh, Dhaivat; Hampapur, Arun
  Authors: He, Qing; Li, Hongfei; Bhattacharjya, Debarun; Parikh, Dhaivat; Hampapur, Arun
  Year: 2013
  Document Type: Paper
  Subject: Railroads; Rail
  Session: 502
  Paper Number: 13-4917
• Dynamic Train-Track Interaction Model to Study Track Performance Under Critical Speed
  Abstract: Field observations and measurements have indicated the existence of a so-called “Critical Train Speed” (varies from as low as 100 km/hour to 300 km/hour) at which moving trains will cause a substantial amount of horizontal and vertical track vibrations. This “mysterious” critical condition is explained as the resonance between the moving train and the Rayleigh wave traveling in the soil (analogous to the “Mach” effect caused by flying object breaking through the sound barrier). However, the wide range of recorded critical speeds (from 100 to 300 km/hour) indicates that a simple conceptual explanation is unlikely to provide a thorough understanding of ground-borne vibration from HSR. Clearly, it is not the train speed itself but the combination of moving train and track structural properties that determines the “Critical Speed”. A dynamic train-track interaction model is developed in this study and utilized to “visualize” the “Critical Speed” phenomenon. From the sensitivity analysis, it is concluded that increasing speed will result in amplified track substructure vibration. This amplified vibration becomes critical when the train speed approaches the subgrade soil shear wave velocity. Furthermore, although subgrade soil properties are the controlling parameters for the critical track response, the rail surface roughness plays an important role as well.
  Authors: Huang, Hai; Chrismer, Steven
  Authors: Huang, Hai; Chrismer, Steven
  Year: 2013
  Document Type: Paper
  Subject: Railroads; Rail
  Session: 502
  Paper Number: 13-4397
• RAIL-NT System for In Situ Measurement of Neutral Temperature in Continuous-Welded Rail: Results from Laboratory and Field Tests
  Authors: Phillips, Robert
  Authors: Phillips, Robert
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Rail
  Session: 502
  Paper Number: 13-3511
• Ultrasonic Tomography for Three-Dimensional Imaging of Internal Rail Flaws: Proof-of-Principle Numerical Simulations
  Authors: Al-Nazer, Leith
  Authors: Al-Nazer, Leith
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Rail
  Session: 502
  Paper Number: 13-3975
• Measuring Concrete Cross-Tie Rail Seat Pressure Distribution with Matrix-Based Tactile Surface Sensors
  Authors: Rapp, Christopher
  Authors: Rapp, Christopher
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Rail
  Session: 502
  Paper Number: 13-4908