In 2010, several European countries (Germany, Britain and the Netherlands), published a new or a revised design guideline for the design of piled embankments. France will follow in 2012. Both the Dutch (CUR226) and the German design guideline (EBGEO chapter 9) based their design calculations (for the vertical load) for the geosynthetic reinforcement on Zaeske’s model (2001). This model consists of two calculation steps: (1) the load distribution (arching) and (2) the load-deflection behaviour of the membrane. In the Netherlands, a research program is carried out for further optimizing the Dutch design guideline. This research program consists of several long-term field studies, an extensive laboratory test series and finite element analysis. The test set up of the laboratory makes it possible to evaluate specifically calculation steps 1 and 2 separately and develop modifications of the model. This paper describes the field studies and the laboratory experiments briefly and gives an overview of the main results.