Massive machine buried under the Channel

A tunnel boring machine weighing over a thousand tonnes has been buried beneath the English Channel for more than 30 years, never to be retrieved. It was deliberately left in place by British engineers during the completion of the Channel Tunnel in 1994.

Tunnel boring machines cannot retreat

Tunnel boring machines are designed to move forward only, as they lay concrete rings behind them, which close in on the machine’s rear. This makes it physically impossible for the machine to retreat once it has dug through the tunnel.

French machine dismantled, British one buried

While the French tunnel boring machine was completely dismantled after finishing its work, the British machine was diverted off the main route and sealed in concrete. This decision was made to avoid the impracticality and high cost of retrieving it from the seabed.

Symbolic handshake in the tunnel

On December 1, 1990, at precisely 12:12, French worker Philippe Cozette shook hands with British worker Graham Fagg in the middle of the tunnel, marking a historic moment in the construction of the Channel Tunnel. This event symbolized the successful connection of the two sides of the Channel.

Precision in tunnel alignment

Before the handshake, a reconnaissance borehole had successfully connected the two sides of the tunnel with an error of only a few centimeters after drilling 38 kilometers. This level of precision remains impressive even today.

Unusual fate of one tunnel machine

One of the eleven tunnel boring machines used in the project had a very different fate. It was sold on eBay in 2004 for 39,999 pounds, showing that some of these massive machines can find unexpected second lives.

Engineering decisions shaped by geology

The different fates of the British and French tunnel boring machines were influenced by the geological conditions on each side of the Channel. The French side had more humid soil, which slowed progress, while the British side had more favorable conditions for digging.

Collaboration and divergence

The Channel Tunnel project was a joint effort involving five British and five French companies. Despite the collaboration, each team handled the fate of their own machines differently, reflecting distinct cultural and technical approaches on either side of the Channel.