TTC OPERATED BY ENSCO
FRA Tools and Training for CWR Management Advanced Tools for Managing Continuous Welded Rail (CWR) Radim Bruzek, R&D Program Manager, ENSCO, Inc., Springfield, VA Robert Wilson, Program Manager, Track Research Division, Federal Railroad Administration Office of Research, Development, and Technology, Amherst, MA
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roper Continuous Welded Rail (CWR) management is a challenging but important aspect of railroad maintenance. Railroads must properly manage Rail Neutral Temperature (RNT) and rail stresses in CWR track to minimize the risk of track buckling and pull-aparts. According to incident reports submitted to the Federal Railroad Administration (FRA) and listed in its Safety Database (https://railroads. dot.gov/safety-data), there were over 100 mainline derailments in the last 10 years
caused by buckled track (T109 cause code only). The average direct cost of these derailments was $720K per incident, which is a higher average cost than most other track-caused derailments. The highest direct cost T109 derailment was over $3.2 million. These direct costs do not include injuries, fatalities, emergency response, evacuations, and legal costs. The number of incidents and their impact on operations shows how important it is to better manage CWR through more effective CWR policies and procedures, industry training on those procedures, and consistently improving CWR procedures through new R&D technology developments. FRA defines CWR as rail welded together that exceeds 400 feet in length. Once rail is installed this way, it remains CWR regardless of the number of joints or plugs installed subsequently. Welded rail can experience both tensile and compressive forces because it is restrained from expanding and contracting. Typically, tensile forces occur in cold winter temperatures and often lead to pull-aparts and rail breaks. Compressive forces occur during warm summer temperatures and may cause track buckles, which are also called sun kinks. RNT is a rail temperature at which the net longitudinal force in the rail is zero and is often associated with the temperature at which the rail was installed. Railroads
typically desire a relatively high RNT to avoid track buckling. To accomplish this, the rail often needs to be artificially lengthened by mechanical stretching or heating to replicate being installed at that higher temperature. After installation, the RNT can change and therefore RNT management is a key aspect of proper CWR management and buckling prevention. Variations in RNT can be caused by a rail break or rail flaw repairs that do not return the rail to the desired RNT. Other events that can cause RNT changes include track maintenance (tamping), curve movement, and undesired longitudinal rail movement caused by wheel/rail forces (often referred to as “running rail”). RNT currently cannot be easily estimated in a non-intrusive manner. For example, two predominate RNT measurement methods are cutting the rail and measuring the gap or using a VERSE machine that requires removing all the fasteners in a span to pull the rail upward. The development of an accurate, nonintrusive, RNT monitoring system that can measure RNT continuously along the track remains a high-priority industry need. FRA is actively researching several concepts to help address this need in the future. CWR management is regulated by Federal Track Safety Standards 49 CFR § 213.118 and 213.119. Section 213.118 requires railroads to create and use CWR procedures and conduct an annual training program.
Figure 1. CWR-SAFE Buckle Module User InterfaceIntegrated Moving Average (ARIMA) model.
4 Railway Track & Structures // May 2023
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