Case Study: GeoNext achieves 7‑mm 3D tunnel survey accuracy for Schiphol maintenance with Trimble

Detailed 3D scan of a tunnel supports railway maintenance program

GeoNext, a Dutch geodetic engineering firm working for ProRail, was tasked with producing a highly accurate 3D model of the 6.5-km dual-track Schiphol Tunnel—a critical link between Amsterdam and Schiphol Airport. The project required strict 7-mm accuracy, had no GNSS availability underground, and needed to be completed within limited maintenance windows to avoid disrupting heavy passenger traffic.

GeoNext used Trimble technology—TX8 3D laser scanners, S7/S9 total stations, R10/R12 GNSS receivers and Trimble RealWorks—setting GNSS points outside at emergency exits and tying targets inside the tunnel. With about 750 scans (20 m spacing, 5–10 m overlap) collected over four weekends and processed into an RD‑NAP point cloud and MicroStation 3D model, the team met the 7‑mm accuracy requirement and delivered fast, reliable results to support maintenance and upgrades.

GeoNext

Daisy Sparla

Project Leader