Randstadrail is the future light-rail link between the cities of Rotterdam, The Hague and Zoetermeer, the Netherlands. In the city area of Rotterdam a shield tunnel will be built for two single track tunnels. The tunnel crosses an intensively used railway track, called the Gouda Link, built on an embankment of saturated loose sand, constrained by very soft clay and peat layers, and reaching almost the Pleistocene sand layer. Boring through and just beneath this loose sand imposes some geotechnical risks, in particular the risk of liquefaction due to monotonic loading. In order to reduce the risks of uncontrolled movements (liquefaction, settlement) during the boring process several design options have been investigated. This paper describes the model test for one of the considered options, densifying the embankment by compaction grouting. The aim of the test was to gain insight in the mechanism and effectiveness of compaction grouting in loosely packed sand. Two effects of compaction grouting are discussed in more detail: i) the change on density and ii) the change on stress level.