Imagine a hidden world beneath the bustling runways of Schiphol Airport. This is the realm of the Schipholtunnel and Buitenvelderttunnel. These tunnels are more than just concrete tubes. They are vital arteries connecting Amsterdam and its airport.
The Schipholtunnel is part of a 17-kilometer passenger train route. It links central Amsterdam to Schiphol Airport. Millions of passengers use this tunnel every year. Any disruption here impacts travel to and from the airport. It also affects trains heading to other cities in the Netherlands, Belgium, and France. Safety and reliability are therefore paramount.
ProRail maintains and expands the Dutch national railway. In 2020, they commissioned GeoNext to survey the Schipholtunnel. GeoNext created a 3D model for planning repairs and upgrades. Accuracy was crucial due to overhead equipment. The model needed to ensure proper alignment for fast-moving trains.
Surveying the tunnel was challenging. There was no GNSS underground and access was limited. GeoNext used laser scanners to quickly collect data. A laser scanner can collect one million points per second. Daisy Sparla from GeoNext said it allowed them to scan multiple tracks at once. They used emergency exits to set GNSS points outside. These points connected to targets inside the tunnel. The team surveyed two 6.5-kilometer dual-track tubes in just four weekends.
After scanning, GeoNext processed the data using Trimble RealWorks. They used Bentley MicroStation Connect to build the 3D model. The speed of the scanner helped them meet the deadline.
Now let’s turn our attention to the Buitenvelderttunnel. It connects Schiphol-Centrum with Schiphol-Noord. This tunnel crosses the Buitenveldert runway. It has four tubes. Three are for motorized traffic and one is for cyclists. Some consider it part of the Schipholtunnel. Unlike the Schipholtunnel, the Buitenvelderttunnel primarily serves local and bus traffic.
Safety is a key focus in both tunnels. The Buitenvelderttunnel had a major renewal completed in 2019. Intersections were created to steer traffic. This allows easy redirection in case of accidents. New concrete was poured, and new safety systems were installed. These include lighting, public address systems, and fire extinguishing systems. The tunnels are monitored 24/7 by the Control Centre.
The Buitenvelderttunnel also showcases art. The bicycle tunnel features a rainbow of colored surfaces. Images of sky, water, wind, and earth add to the experience.
Height detection is active in the Schipholtunnel for the A4 towards Amsterdam. This prevents oversized trucks from damaging the tunnel. Trucks exceeding the height limit are warned. They can exit to the A5 and A9 to avoid the tunnel. Ignoring the warning leads to a tunnel closure and a fine. The tunnel from The Hague to Amsterdam is one of the oldest and lowest in the Netherlands. The other tunnel is relatively high and does not have a height detection system. Damage has occurred due to high vehicles hitting lights and speakers.
The Schipholtunnel and Buitenvelderttunnel are testaments to engineering. They ensure smooth transportation while prioritizing safety and innovation. As you journey through Amsterdam and beyond, remember the hidden infrastructure beneath your feet.