Chapter 4
Railroad Research and Development Program
Section 4.3
Rolling Stock and Components
The Rolling Stock program element places emphasis on the development and improvement of equipment defect detection via wayside and onboard systems. Such detection promotes early defect detection and helps prevent derailments due to equipment failure. It also permits condition-based maintenance of car and locomotive components. This program focuses on a pro-active approach to preventing derailments and equipment failure. This approach will involve risk assessment and mitigation, along with support for safety assurance. This program directly supports the strategic goal: provide analytical and technical support that reduces the number of accidents, deaths, and injuries due to rail equipment defects.
Why a Priority?
The past decade has brought about major changes in the operating environment of today’s railroads. Past mergers, spinoffs, and modal shifts have not only provided new opportunities for railroad operators, but also increased the performance demands on them. Higher capacity freight cars with heavier axle loads and higher speeds result in requirements becoming more stringent with regard to railroad equipment and component performance. Particularly, as more high-speed trains come into service, the contribution of each subassembly or component to overall system safety is increasing.
In 2000, 12.5 percent of all train accidents were related to equipment failure. Specifically, out of 2,983 train accidents, 372 were equipment related, a 16 percent increase over 1999 and a 37 percent increase from 1997. Mechanical components must withstand increased loads and stresses while operating at higher speeds. At the same time, the need for increased payloads in freight trains and the greater comfort demanded by passengers (i.e., reduced noise and smoother ride) are increasing the material and energy resources required to build and operate rail equipment. Subsystems must therefore be lighter and smaller, and offer greater energy efficiency while maintaining and improving performance. Equipment is being utilized more often and for extended periods of time. The demands on rail equipment are becoming more severe.
Objectives
The main program objective is to identify, analyze, demonstrate, and disseminate information about equipment defect detection technology that has the potential to improve the safety and efficiency of railroads in the United States. This program represents a proactive approach to preventing equipment and component failures that may potentially result in derailments. A second objective is to provide the analytical and technical basis to develop equipment safety standards, especially with emerging technologies.
Expected Outcomes
The expected outcome of the Rolling Stock program will be to minimize the occurrence of derailments, premature equipment failure, and undesired emergency brake applications. This program is also expected to fulfill the demands for faster, heavier, and longer trains by extending equipment and material life through early defect detection and the development of advanced materials. Equipment and component condition monitoring will improve safety and reliability as well as promote condition-based maintenance as opposed to time or mileage-based maintenance. The resulting database created by such monitoring will also provide historical data to study equipment and component life, behavior, and failure rates. The development of wayside and on-board detection and control will bring fully Automatic Inspection Stations closer to reality. Research results will be incorporated into equipment safety standards and maintenance practices.
Project Descriptions
ELECTRONICALLY CONTROLLED PNEUMATIC (ECP) BRAKING AND
ON-BOARD MONITORING AND CONTROL SYSTEMS
These systems are component elements of Intelligent Railroad Systems described in Chapter 2 . They enable improved system performance with better safety and efficiency. This research is undertaken with rail industry cooperation.
The train line communications systems on locomotives and rail cars utilized in ECP braking can be used to control train functions and monitor the critical systems and their components for early detection of problems such as overheating of wheels, bearings, and brake pads that could be detrimental to safety. On-board monitoring will allow immediate notification to the locomotive engineer and appropriate personnel through the supporting communication network. Safety critical locomotive functions such as locomotive dynamic brake can also be monitored continuously and "alarmed". The early notification will help reduce the ill effects of sudden equipment failure.
Brake System
New research initiatives are focusing on additional on-board detection and train health monitoring features to be incorporated with ECP brake technology. These features include brake-cylinder and handbrake position sensing, and a running indication of the brake system status. The ECP brake system will provide continuous monitoring of brake system health. This is a new research program that will be expanded during this five-year period. The majority of this work will be conducted in cooperation with the railroad industry. Safety evaluations of advanced braking systems will continue. An advanced handbrake for use on freight railroad cars will be developed and operated in conjunction with the ECP braking system. The new handbrake will be user-friendly and will promote safe and easy braking operations. The handbrake will allow remote activation, brake status monitoring, and will require less force for brake release and set. This is an on-going program area. Research on advanced handbrakes is planned to continue through early FY 2005.
Bearing Systems
If a problem such as overheating of bearings is detected early, then steps can be taken to avoid catastrophic failures. The communications protocol and system architecture developed in conjunction with ECP braking systems can be extended to address these control and monitoring activities. Research has been initiated to develop and introduce onboard monitoring technology for monitoring bearing temperature and truck ride quality, entailing the development of transducers and instrumentation that will be compatible with on-board monitoring and communication on ECP braking systems. The freight car system set-up is shown below in Figure 5.3.1. This program area is planned to continue through 2003.
Figure 4.3.1 Freight Car Sub-System Displaying the On-board Sensor and Communications Devices
Advanced Train Systems
A revenue service demonstration of smart sensors is planned for FY 2002 and FY 2003. Sensor data will be transmitted via communications satellites to a central database for dissemination with an interval-based system approach. This project will be initiated with a 5- to10-car Advanced Train equipped with ECP brakes and onboard monitoring systems with brake piston travel surveillance, ride quality surveillance, derailment detection, wheel overload conditions, advanced couplers incorporating air and electrical connections, advanced parking brake with remote release, in-train force and impact monitoring, derailment detection, and hot bearing detection. Advanced Train systems could also be operated on main lines as well as in industry switching service and yards. Collectively these features reduce the risk of injury to crews by avoiding high-risk tasks, such as coupling cars and air hoses. Continuous monitoring of onboard conditions will also reduce the potential for derailments. FRA wants to demonstrate this element of Intelligent Railroad Systems to obtain industry acceptance of the concept. For these features to be deployed by the industry, they need to be demonstrated successfully as an overall, integrated system.
As additional companies enter the advanced braking systems arena, brake system safety evaluations and other analysis will be required. Due to increased traffic, car and train weight increases are expected. Thus, research efforts will focus on the development of a Train Dynamic Simulator (TDS). The TDS will be used to evaluate Train Safety and Energy Efficiency of equipment and the railroad as a system. Brake system reliability must also be addressed through further research. Continuous monitoring of locomotive dynamic brake system operability will be addressed further. Train line communications must eventually be implemented safely to enable Intelligent Railroad Systems. Continued support will be provided to the FRA Office of Safety.
WAYSIDE MONITORING
Derailments due to equipment or component failure must be prevented. To accomplish this goal, development of a new generation of equipment defect detectors, which have the ability to detect defects at their early stage of failure and with a high degree of confidence, is needed. These detection systems must show increased detection ability, control, and improved reliability. Wayside detection research will continue to focus on improvements in this area, as well as focus on the development and establishment of advanced inspection stations. These stations will consist of improved wayside detection systems; possibly using advanced imaging methods. Such systems will monitor wheel wear status, car and suspension dynamics, and improve the reliability, maintainability, and accuracy of hotbox detectors. They will also inspect railcar wheels to identify symptoms of brake defects, hot wheels, and sliding wheel detection. Wayside detection systems are also a component element of Intelligent Railroad Systems as described in Chapter 2.
Research efforts will focus on the development of advanced inspection stations. These stations will be located in high traffic density locations where they will provide the most significant coverage of defects. These stations will involve the inspection of bearing defects, worn wheels, worn trucks, and even truck hunting. The identification of truck signatures is critical because it will provide insight into a truck’s condition. Figure 4.3.2 displays a normal truck signature and a warped truck signature. Warped truck signatures increase the potential for derailments. Figure 4.3.3 shows the set-up for the Wayside Inspection test site in Loudon, Tennessee. This work is being done in cooperation with the railroad industry. Such stations will provide more rigorous safety inspections than are possible visually, and demonstrate increased reliability and detection ability. Alternative new technologies will continue to be explored for detecting defective bearings and cracked wheels.
Figure 4.3.2. Normal Truck Signature vs. Warped Truck Signature
Figure 4.3.3. Wayside Inspection Station Test Site at Loudon, Tennessee
Commuter railroads, in particular, experience overheated wheels because of their frequent stops. Wheel overheating during braking can result in undesirable stresses in wheels as illustrated in Figure 4.3.4. The beneficial effects of quenching during manufacture can be overcome by significant stresses induced due to rapid heating. High-speed thermal imaging (“thermography”) needs to be developed to the point that it can be incorporated into advanced wayside inspection stations. Thermal imaging improves reliability, maintainability, and accuracy of hotbox detectors and can also inspect rail car wheels to identify symptoms of brake defects (i.e., sliding wheel detection). Thermal imaging systems scan the entire wheel, bearing, and truck assemblies. They can operate as a stand-alone unit or with the addition of an Automatic Equipment Identification (AEI) reader. Research will continue to determine equipment defect characteristics (i.e., bearing acoustic signatures) in an effort to develop the ability to predict defects and prevent failures before they occur. Research into the advanced imaging of bearings will continue through the end of FY 2003.
Wheel research will continue to focus on nondestructive testing methods and the development of in-service inspection of wheels for limiting wear and related reasons for removal. Efforts will focus on the development of in-situ
detection systems to assess the stress state in wheels, as well as detect and define cracks and/or other flaws in the tread. Research to measure wheel wear in place will also be initiated and supported. Wheel research is an on-going activity.
Bearing life with an increased axle load will be evaluated and improved. It may even be necessary to develop and evaluate new and improved bearing materials and designs. Basic research, applied research, and laboratory testing will be conducted. Bearing research will continue through the end of FY 2003.
MATERIAL IMPROVEMENT AND DESIGN
Continuing research is needed for improvement of materials used in railcar components. For instance, coupler material needs to be more crack tolerant with higher strength, improved fracture toughness, and cleanliness of the cast steels. The demand is for steels that are readily available without pre- or post-heat treatments. Research in the area of improved coupler material and design will be continuing during this five-year period.
For the work proposed, research metallurgists working with casting manufacturers will serve as consultants. The group will analyze present cast steels to determine ways of modifying the material to meet the present and future demands on couplers. Test castings will be poured, and tests on hardness crack growth, and weldability will be run to determine possible material improvements. The new types of cast steel will also be used for other railroad castings.
Fully Automatic Coupler
Current freight car couplers have no provision for automatically making the braking air connection or any electrical connections. These couplers have a limited gathering range (misalignment tolerance) and must be manually prepared for coupling, which poses a risk to the operator. Research initiated in FY 1998 under the Small Business Innovative Research (SBIR) program will continue to develop a mechanically compatible knuckle-type coupler that will couple to standard couplers and which when coupled to a like new design coupler will provide for automatic air and electrical connections. Automatic coupler research is planned to continue through the end of FY 2003. Research will continue to look into remote means for mechanical uncoupling and remote operation of angle cocks.
Advanced Cushioning Devices
Both freight and passenger cars are subject to yard impact forces. The longitudinal impacts are controlled with hydraulic cushioning devices which employ hydraulic metering of oil through small orifices; thereby, preventing high coupler loads and acceleration from acting on the car and its lading. However, the travel associated with those devices is detrimental in over-the-road train operation. It results in excessive slack action that affects safe operation. Train action forces may lead to derailments and/or gage spreading. An automatic or remote means to electrically lock-out the orifices prior to trains departing yards—perhaps utilizing the ECP brake train line—will be researched and developed. Research on advanced cushioning devices will continue through early FY 2003.
Advanced Handbrake
Research was initiated in FY 1998 under the SBIR program to develop an automated handbrake to hold cars stationary on level track or on grade to prevent car runaway as sometimes occurs with present handbrakes. This new handbrake is compatible with the present air brake system and will be compatible with the newly developed ECP brake system. Phase 1 has been completed and Phase II is slated for completion in FY 2002.
Figure 4.3.4. Wheel Profiles Showing Estimates of Thermal Stresses in New and Used Commuter Car Wheels
Table 4.3
Planned Timeline for Rolling Stock & Components Projects
