Developing a better understanding of TOR effectiveness

Written by Mischa Wanek-Libman, Editor, Railway Track & Structures; and Engineering Editor, Railway Age

The American Railway Engineering and Maintenance-of-Way Association's (AREMA) Annual Conference being held in conjunction with Railway Interchange 2015, held six breakout sessions Tuesday, including nine in the Track session.

One of the presentations was delivered by L.B. Foster Rail Technologies Corp. and outlined the idea of using lateral forces as an indicator for determining an efficient friction management implementation plan.

The company notes the benefits of effective top-of-rail (TOR) friction control in heavy-haul applications is well understood, but says optimizing the deployment of TOR friction control in a given territory requires reliable estimates of both the benefits and costs of deployment.

“As the benefits can take a substantial amount of tonnage (and time) to verify and quantify, the analysis when evaluating alternative TOR materials tends to focus on the cost side of the equation. Rather than comparing cost per unit volume between materials, a more effective approach involves comparing the Cost Per Treated Mile (CPTM), which is a function of material performance and corresponding factors, such as carry distance and required application rates,” said the company.

L.B. Foster Rail Technologies said direct measurement of friction levels to determine the TOR effectiveness is difficult due to a host of influencing factors, which has lead to the measurement of lateral forces (and L/V ratios) using strain gauge based systems has emerged as the most reliable means of assessing TOR friction control effectiveness.

“While a comparison of lateral forces (e.g. between baseline and treated conditions) to determine TOR effectiveness is simple in concept, there are a number of critical operating factors that can have deleterious effects on the statistical validity of the results,” said the company.

“With different material concepts for TOR products available, simply assessing the price per volume of the material will not provide a reliable criterion for choosing the most economic product. The proposed CPTM model can help in determining the actual costs for effectively treating a mile of track including factors like application rate, carry-down and traffic conditions among others. As the CPTM model is highly sensitive to carry-down and application rate a thorough test methodology to determine these factors is recommended. Lateral forces and their reductions can be used as a reliable indicator for the carry-down characteristics of a material. The filter methodology proposed will provide reliable and statistically significant lateral force information for determining the carry-down distance of a TOR material.

“The CPTM model will provide reliable economic product information based on short term trial information. However, long term factors like the impact of a TOR material on corrugation growth, wear, rolling contact fatigue development and grinding cycles should also be considered for selecting an appropriate product for TOR application. This holistic concept will provide an objective approach for selecting the appropriate and most economic TOR product for an infrastructure owner,” said L.B. Foster Technologies.

More on the proposed CPTM model can be viewed in the AREMA 2015 Conference Proceedings.

Additional presentations heard by attendees of the Track Breakout Session included Rail Life Extension and Improved Welding Strategies in HAL Revenue Service; Shoulder Ballast Cleaning Effectiveness; Ballast Properties and Degradation Trends Affecting Strength, Deformation and In-Track Performance; Rapid Soil Stabilization Methodology for High Volume Mainline Track; The Rise of Steel Ties: Understanding of Steel Ties and Applications; Asphalt Railway Trackbeds: Recent Designs, Applications and Performances; Evaluation of Turnout Foundation Improvements for HAL Service and Designing of Well-Performing Railway Transitions.

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