https://tube.blueben.net/videos/watch/492b060c-081f-4c42-b055-cd398d5037f0 16 kilometers under the Chiltern Hills, dug for High Speed 2 over 33 months. This is the engineering megaproject most people have never heard of — and it nearly came apart every other mile. In this video, we go inside the Chiltern Tunnel from Florence's cutter head biting into chalk in May 2021 to the breakthrough at South Heath in February 2024. You'll see how Herrenknecht's Variable Density TBMs — the first in the UK — switched modes mid-drive when the chalk turned to liquid. How crews swapped 250-kilogram disc cutters in pressurized chambers, suited up like saturation divers 80 meters underground. How Florence drove straight through four 18-meter concrete ventilation shafts without stopping. How 38 cross-passages got hand-dug in 30-centimeter bites. And how 140 meters of bright orange clay nearly beat the longest tunnel in British history with two months left on the clock. Three weeks later, on March 22, 2024, Cecilia followed her sister out into the same field. Two parallel bores, end to end — the longest tunnel ever driven on the British island, ready for HS2 trains that haven't run yet. #tunnel #megaprojects #beyondfacts Join this 'Paper Pilot Club' to get access to perks: https://www.youtube.com/channel/UCzgWZmqmKpmsr4oPWITusKA/join SUBSCRIBE: https://www.bit.ly/beyondFactsSUB Credits: https://docs.google.com/document/d/1wDTsXOC6z-D3gArkWnyzsMx2WjY9rJVUfa0WghZoTnE/preview Mon, 25 May 2026 22:20:33 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://tube.blueben.net https://tube.blueben.net/client/assets/images/icons/icon-96x96.png https://tube.blueben.net/videos/watch/492b060c-081f-4c42-b055-cd398d5037f0 All rights reserved, unless otherwise specified in the terms specified at https://tube.blueben.net/about and potential licenses granted by each content's rightholder.