Technical Reports

Quantification of the Effectiveness of Low Solar Absorptivity Coatings for Reducing Rail Temperature

  • 14
  • Jan
  • 2016
AUTHOR: Federal Railroad Administration
OFFICE: RPD
SUBOFFICE: RPD-31
REPORT NUMBER: DOT/FRA/ORD-15/37
KEYWORDS: Track buckling; sun kink; rail neutral temperature; low solar absorption coating; thermal reflective coating
ABSTRACT: Due to the thermal expansion properties of steel, the risk that a track will buckle increases as the temperature of the rails increase. Therefore, it is desirable to keep rail temperature as low as possible, especially on hot summer days. Empirical data and modeling has shown that on such days, the peak temperature of the rail could reach as high as (or slightly exceed) 35 degrees Fahrenheit above the peak ambient temperature. If the peak ambient temperature for a given day is 100 degrees Fahrenheit, for example, then the peak rail temperature can be expected to be approximately 135 degrees Fahrenheit, provided there is little cloud cover and no precipitation. This project’s objective was to quantify the effectiveness of various low solar absorption coatings for reducing rail temperature, thereby reducing the risk of track buckling. The results indicate that some of the coatings tested can significantly reduce the temperature of a rail when the coated rail is compared to the temperature of an uncoated rail. However, further studies are needed to ensure the durability of these materials when applied to in-service track.

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