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In both high speed and freight rail systems, the modern construction method is Continuous Welded Rail (CWR). The
purpose of the CWR method is to eliminate joints in order to reduce the maintenance costs for both the rails and the
rolling stock. However the elimination of the joints increases the risk of rail breakage in cold weather and buckling in hot
weather. In order to predict the temperature at which the rail will break or buckle, it is critical to have knowledge of the
temperature at which the rail is stress free, namely, the Rail Neutral Temperature (Rail-NT).The University of California
at San Diego has developed an innovative technique based on non-linear ultrasonic guided waves, under FRA research
and development grants for the non-destructive measurement of the neutral temperature of railroad tracks. Through the
licensing of this technology from the UCSD and under the sponsorship of the FRA Office of Research and Development,
a field deployable prototype system has been developed and recently field tested at cooperating railroad properties.
Three prototype systems have been deployed to the Union Pacific (UP), Burlington Northern Santa Fe (BNSF), and
AMTRAK railroads for field testing and related data acquisition for a comprehensive evaluation of the system, with
respect to both performance and economy of operation. The results from these tests have been very encouraging. Based
on the lessons learned from these field tests and the feedback from the railroads, it is planned develop a compact 2nd
generation Rail-NT system to foster deployment and furtherance of FRA R&D grant purpose of potential contribution to
the agency mission of US railroad safety. In this paper, the results of the field tests with the railroads in summer of 2013
are reported.
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