Experimental Validation of Track Inspection Trolley Using a Rigorous Self-Checking Procedure

International standards establish strict criteria for the measurement of railway track geometric parameters by track inspection trolleys. In the case of the rails’ internal geometry, the values of some parameters (such as track gauge and cant) must be determined directly by a set of high-resolution and high-precision sensors. To ensure the quality of the data (or detect any mechanical misalignment), prior to the observation program the instrument needs to undergo a simple but rigorous check, a procedure the authors argue the regulations fail to properly define. A simple but rigorous routine validation procedure is put forward with which to check the correct functioning of the measurement process by providing estimates for the expected error and variance of the measured parameters. A methodological proposal for in-field observations and error analysis is described in depth. A practical application is described as applied to a track section of the Madrid–Extremadura–Portuguese Border (Spain) high-speed line, which is currently under construction, analyzing the experimental data for the parameters track gauge and cant.