Sub-surface obstacle detection, NL

Precision sub-surface imaging to select position of foundations

Uncertainty in the soil characteristics at a bridgehead between the planned “RandstadRail” viaduct and the main railway line between The Hague and Leiden, necessitated a change in design of the foundations for the elevated junction. Discovery of a substantial layer of peaty soil called for a foundation on piles. The expected presence of several grout anchors from an underground car park threatened to coincide with the location of these piles. Fugro used a custom-made 3D magnetic gradiometer CPT system to detect anchors at each pile location (some inclined to 11°). Pile positions were then relocated to an accuracy of 5cm to avoid the anchors.