"Railroads will be expected to utilize established methods to conduct required rail inspections, but they will also have the flexibility to utilize..." (Vantuono, 2020)
References:
Vantuono, W. C. (2020, August 28). FRA Green-Lights Continuous Ultrasonic Track Inspection. Retrieved from Railway Age: https://www.railwayage.com/mw/fra-green-lights-continuous-ultrasonic-track-inspection/?RAchannel=freight