Non-contact methods of rail assessment for a railroad track

A non-contact, reference-free method for estimating Rail Neutral Temperature (RNT) to estimate the temperature at which the rail of a railroad track is stress free, comprising:

• using at least one camera for periodically imaging shape and curvature of a railroad track at different times realtive to at least one fixed physical reference comprising a rail anchor while tracking thermal conditions thereat to determing full field deformations of the railroad track and strain thereof under varying thermal conditions;
• analyzing resulting data to determine a minimum strain condition and corresponding temperature, said analyzing including computing through regression analysis of the measurements change in curvature of the track rail at the location of the at least one fixed physical reference as a function of temperature, to determine a temperature that minimizes the function to thereby establish an estimate of the RNT;
• and
• periodically repeating said imaging and analyzing steps consecutively and estimating changes over time in RNT of a railroad track being monitored.