The world’s longest and deepest undersea road tunnel is being inbuilt Norway, meant to chop journey time between main cities and grow to be a part of a ferry-free freeway alongside its western coast.
The 27-kilometer (17-mile) lengthy tunnel is referred to as Rogfast — quick for “Rogaland fastforbindelse,” after the title of the area it’s in and the Norwegian phrase for “fixed link.” At its deepest it will likely be 392 meters (1,286 toes) under sea stage.
Construction began in January 2018 however was halted in late 2019 because of predicted price overruns that led to the cancellation of current contracts and a restructuring of the venture. Work resumed in late 2021 and the tunnel is now slated for completion in 2033, at a value of roughly 25 billion Norwegian kroner (about $2.4 billion).
“The tunnel will significantly improve connectivity along the Norwegian west coast, by creating a faster and more reliable link between the Stavanger and Haugesund regions,” mentioned Anne Brit Moen, a venture supervisor at Skanska, the multinational development firm that’s building the northern a part of the tunnel, which is the deepest part and is 9 kilometers (5.5 miles) lengthy.
By changing the present ferry connections, Rogfast will scale back journey time between Bergen and Stavanger — respectively the second and fourth largest Norwegian cities by inhabitants — by round 40 minutes and make each day commuting a lot simpler, Moen added.
The tunnel will encompass two separate tubes, every with two site visitors lanes, designed completely for road site visitors, and can sport a somewhat uncommon design aspect roughly midway by: a double roundabout, 260 meters deep, linking out to a connection tunnel resulting in the island of Kvitsøy, Norway’s smallest municipality.
Building a tunnel of that size below the sea poses a number of technological challenges. Like most fashionable tunnels, to avoid wasting time, Rogfast is being constructed from each ends concurrently, with the objective of getting the two development groups meet in the center inside a margin of error of simply 5 centimeters (1.97 inches).
Achieving this stage of precision requires cautious measurements utilizing lasers and different refined tools. A spinning, mirrored laser scanner measures a newly excavated tunnel portion, amassing 2 million information factors per second to create a “digital twin” of the tunnel. That can then to be checked towards the design plans for any inaccuracies.
“It’s a little bit away from the romantic view of the of the surveyor looking through an eyepiece,” mentioned Burkhard Boeckem, chief expertise officer at Hexagon, the firm that is offering the measurements for the tunnel.
The 5-centimeter (1.9-inch) margin is amongst the strictest in the world, however can save time, cash, waste, and emissions by avoiding errors: “If you deviate from this, you create so much more material that needs to be taken out, and then so much more to be filled in again — it’s a lot of whole trucks. So, it’s not just a risk factor, but also a very financial factor.”
Technically demanding
The Rogfast venture is a part of a revamp of the E39 coastal highway, a 1,100 kilometer (684-mile) road that runs from Trondheim in the north to Kristiansand in the south. Today it takes 21 hours to drive the whole size of the road, which incorporates seven ferries. The objective is to make it ferry-free by building tunnels and bridges, slicing journey time in half. Completion is not anticipated earlier than 2050.
Rogfast is one in every of the most formidable and technically demanding parts of that plan, and development hasn’t been hurdle-free, in response to Moen. “The main challenge so far has been to find good enough grouting methods to seal the rock,” she defined. “We are now 300 meters (984 feet) below sea level, and we have already had quite extensive saltwater leaks in the tunnel system. Since we are going all the way down to 392 meters (1,286 feet) below sea level, we’re focusing on finding the best methods to maintain safe and efficient working conditions for everyone.”
The tunnel additionally requires measures to guard motorists from air air pollution. It will make use of a longitudinal air flow system — which usually use jet followers to create airflow — complemented by shaft air flow extending as much as Kvitsøy. “This combination is designed to ensure effective air circulation and safety throughout the tunnel’s considerable length,” mentioned Moen.
An actual-time incident alert will even be applied to establish occasions similar to breakdowns or congestion, and cameras and radar will monitor autos.
Although jobs can be finally misplaced from ferry closures, Rogfast will strengthen entry to different jobs, schooling, and public providers for native communities, Moen mentioned, and have optimistic results on the native financial system and the seafood business, as logistics prices will go down and firms will be capable of function throughout a wider space. “The project also creates substantial employment during construction and lays the groundwork for more sustainable and integrated regional development along Norway’s fractured western coastline,” she mentioned.
Currently, the title of world’s longest tunnel with an undersea part belongs to the Seikan Tunnel in Northern Japan, a railway-only tunnel that has a complete size of 53.85 kilometers (33.5 miles), with an undersea part spanning 23.3 kilometers (14.5 miles).
The Channel Tunnel, which is additionally railway-only and connects England to France, is shorter, at 50.46 kilometers (31.35 miles), however its 37.9 km (23.5-mile) undersea part is longer than Rogfast. Rogfast, nonetheless, might be a lot deeper under sea stage than both Seikan or the Channel Tunnel, which backside out respectively at 240 meters (790 toes), and 115 meters (377 toes).