This research was conducted in Poland comparing a Z + F system with a Riegl which used the VMX 250 to measure the gauge of railroad track. The point of these tests was to answer the question of whether the choice of laser scanning as the methodology for measuring the structure gauge of railway lines is correct and whether the tested measuring systems meet the accuracy requirements.
The measurements were designed so as to provide various elements of the railway infrastructure, the track geometry and the installed geodetic control network. This ultimately made it possible to reduce the time for the preparation of geodetic reference measurements for the testing of the accuracy of the selected systems.
The research was conducted a couple of years ago, but the detailed methodology is of interest.