Railway Track & Structures - October 2007 - (Page 43)

rail is an important track maintenance and safety issue. Thermal forces are generated when the rail temperature varies from the rail’s neutral temperature, i.e., the rail temperature at which the longitudinal force is zero, which is typically the rail’s laying or installation temperature. Compressive forces are produced when the rail temperature is higher than the RNT and tensile forces are produced when the rail temperatures are below the RNT. High compressive forces can cause track buckling, while high tensile forces can accelerate rail defect growth and cause rail joints to fail or pull apart in cold weather, with both being potential derailment causes. Longitudinal forces are controlled by installing and maintaining the rail at RNT levels within specified limits. However, it is a known fact that the RNT will vary over time and that it typically shifts to a lower value that can increase the risk of track buckling. These lowered RNT values can result from rail repair or other maintenance work undertaken during cold weather and from excessive rail movement. A key impediment to knowing these low and potentially dangerous RNTs is a lack of adequate measurement capability, which has eluded researchers for the past 30 years. The RSM has been developed over 25 years of R&D to fulfill this need. Moreover, the RSM and its StressNet™ database have been recently expanded to support specific industry needs to not only measure RNT but interpret it for practical application to enhance overall cwr safety and performance. More specifically the RSM and StressNet™ technology: • Measures longitudinal force and rail neutral temperature. • Detects rail breaks and track buckles. • Alerts on potential buckling hazards. • Enables more-effective rail break/defect repairs. • Monitors rail joint condition. Figure 1. Data flow from the RailStress Module to the Web-accessible StressNet™ database. basic concept, while the last two were used to perfect long-term survivability and seamless data collection. The fourth and fifth generation RSM designs share a consolidated methodology of collecting, storing and databasing the stress and temperature at their respective installed locations. The current (fifth) generation exploits relatively-new IEEE802.15.4 radio technology and complementary flexibility allows for any or all of these techniques to be deployed, depending on the needs of the operating railroad. Figure 2 shows the various uses and deployment options of the RSMStressNet™ System. RSM installation Installation of the modules is a very simple and efficient process. All installation hardware is included in a RSM installation kit provides easy mounting. RSM-StressNet™ System The rail-mounted hardware represents 25 years of development, starting with a stress-measurement circuit first developed at Battelle Labs by one of the authors. By the late 1980s and early 1990s, track research was being routinely performed with this circuit on Amtrak, CSXT, TTCI and UP. The first three generations of hardware were used to prove the viability of the www.rtands.com antenna designs that allow for a seamless collection process in a hardened design capable of surviving normal freight railroad operations and maintenance. The power management of this design allows for the 10-plusyear useful life of the RSM and the ability to collect the data with a variety of intermediate devices: • Hand-held reader carried by a track inspector. • End-of-train device. • Hi-rail inspection vehicle. • Wayside (fence post) reader. As shown in Figure 1, design custom installation kit that allows module application in remote areas without any commercial power. The portable grinder and battery charger (for cleaning the rail), along with a custom strain-gauge welder and installation fixture/template, allow a module to be bonded to the rail via two-part epoxy in as little as 20 minutes. The picture above shows the entire installation kit and module (blue module held by aluminum installation fixture) ready for application on the rail. Once the RSM is mounted to the rail, it automatically begins collecting Railway Track & Structures October 2007 43 http://www.rtands.com

Table of Contents Feed for the Digital Edition of Railway Track & Structures - October 2007

Railway Track & Structures - October 2007 Contents On Track Industry Today Supplier News AREMA News NRC News TTCI R&D Crossties by the Billions Provide Essentials for Full Support Modern Tools Manage Risk M/W Challenges: Better Management of Thermal Forces in CWR TTCI Celebrates 25 Years as Facility, 10 as Part of AAR Products and Literature People Calendar Sales Representatives Website Directory Advertisers Index Professional Directory Classified Advertising Chicago Perspective

Railway Track & Structures - October 2007

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