But Measurable Nonetheless. Worlds longest road tunnel: The 24.5 kilometer Laerdal in Norway opened on Nov. 27, 2000, as part of the E16 Bergen-Oslo highway. Began in 1995.Longest rail tunnel: The 53.9 kilometer marine railway tunnel, Seikan, joins the Japanese islands of Hokkaido and Honshu.Largest underground construction project (depending on how you count): The Chunnel was opened for traffic in March 1994 and cost $14 billion for 50 kilometers of tunnel and two terminals with all rolling stock. Employed 11 TBMs on two large-section running tunnels and smaller service tunnel driving from shafts at Sangatte in France and Shakespeare Cliff in England. Two major crossover chambers under the Channel.Largest unsupported span: Gjovik Ice Cavern, Norway. Dimensions of hall are 62 meters wide, 91 meters long and 25 meters high. Excavated in eight months during 1991 for the 1994 Lillehammer Winter Olympics.Largest underground treatment plant: Viiki sewage plant in Helsinki was constructed from 1988 to 1991 to serve a population of 650,000 together with associated industry. Involved excavation of 997,000 cubic meters of rock. Source: TunnelBuilder.com Related content news analysis DHS unveils one common platform for reporting cyber incidents Ahead of CISA cyber incident reporting regulations, DHS issued a report on harmonizing 52 cyber incident reporting requirements, presenting a model common reporting platform that could encompass them all. By Cynthia Brumfield Sep 25, 2023 10 mins Regulation Regulation Regulation news Chinese state actors behind espionage attacks on Southeast Asian government The distinct groups of activities formed three different clusters, each attributed to a specific APT group. By Shweta Sharma Sep 25, 2023 4 mins Advanced Persistent Threats Cyberattacks feature How to pick the best endpoint detection and response solution EDR software has emerged as one of the preeminent tools in the CISO’s arsenal. Here’s what to look for and what to avoid when choosing EDR software. By Linda Rosencrance Sep 25, 2023 10 mins Intrusion Detection Software Security Monitoring Software Data and Information Security feature Top cybersecurity M&A deals for 2023 Fears of recession, rising interest rates, mass tech layoffs, and conservative spending trends are likely to make dealmakers cautious, but an ever-increasing need to defend against bigger and faster attacks will likely keep M&A activity steady in By CSO Staff Sep 22, 2023 24 mins Mergers and Acquisitions Data and Information Security IT Leadership Podcasts Videos Resources Events SUBSCRIBE TO OUR NEWSLETTER From our editors straight to your inbox Get started by entering your email address below. Please enter a valid email address Subscribe