Light Weight Deflectometer for particularly narrow trenches is currently more requested for use in the Trenching method. The time and money-saving Trenching method with particularly narrow trenches of just 10-15 cm wide is mainly used for the expansion of the fibre optic network. When filling and compacting these narrow trenches, a conventional Light Weight Deflectometer with a 30 cm load plate cannot be used because the load plate does not fit into the narrow trench. In order to enable users to provide proof of compaction even in these narrow trenches, TERRATEST® has now developed the new TERRATEST 4000 TRENCH. The new TRENCH with a 10 cm narrow, oval load plate and a 5 kg drop weight fully meets these requirements. The measured values ascertained on footpaths and cycle paths correspond approximately to the values determined by a traditional light weight deflectometer with a 30 cm load plate and 10 kg drop weight.