Batignolles tunnel

The Batignolles tunnel consists of two distinct subterranean passages carved beneath the seventeenth arrondissement. Trains heading toward Saint Lazare station travel through these dark corridors, which were bored through the limestone bedrock in the mid nineteenth century. In nineteen twenty-one, a collision involving a commuter train and an express killed forty passengers inside the tunnel. Rescue crews struggled to reach the wreckage in the smoke-filled darkness, leading to permanent changes in how the French railway managed signaling and safety protocols for underground traffic.