The publication in 2017 of ISO documents 11819-2 (CPX method) and 11819-3 (reference tyres) has made it possible to conduct measurements of noise properties of road surfaces in a standard and reproducible way. However, it is still not well-known what differences one may expect between different CPX equipment. A comparison of CPX trailers in the Netherlands in 2017 gave very positive results, but only two road surfaces were used, and all measurements were made close in time. In practical measurements, more variations in CPX equipment occurs and measurements on a certain test surface cannot take place on a certain day or even week. This study used four CPX trailers, of different designs, and the measurements were made over a time period of 90 days; something that may well happen whenever an authority or organization orders a CPX measurement. In this paper the test equipment and tested road surfaces are described, and the first measurement results are presented.