At 12 cm construction height, the world‘s thinnest ”synthetic composite sleeper“ (as of 2013) received positive test results in autumn 2013 for main line railways (22.5t) for speeds v < 200 km/h from the testing body for transportation route construction at the Technical University Munich.

Based on these favourable results, the German Federal Railway Authority and the Swiss Federal Transportation Office were able to grant operational trials approval in 2014 for the safe use of the 12 cm high FFU synthetic wood railway sleepers.
The Swiss approval also included tunnel installations where wooden sleepers are still installed prior to the replacement.