Submitted by WA ContentsAngelo Renna proposes a submerged floating bridge over the Strait of SicilyItaly Architecture News - Jan 06, 2025 - 13:12 html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd"Architect and landsape designer Angelo Renna has proposed a submerged floating bridge over the Strait of Sicily in Italy.Called Strait of Sicily - Archipelago Floating Bridge, the bridge was developed as an alternative proposal to span over the Strait of Sicily. A submerged floating bridge serves for cars, highspeed trains, and bikes.The sequence of artificial islands supporting the bridge, with Sicily Island in the backgroundDesigned by Angelo Renna and Kittan Kodijat, the bridge supports marine life and minimizes the impact on the environment by including an archipelago of man-made islands at the water's surface.Boats can easily navigate between the islands, and trees and vegetation will grow on the artificial pontoons"The dream of a bridge connecting Sicily to mainland Italy stretches back 2000 years to Roman times, when Consul Metellus strung together barrels and wood to create a floating bridge to move 100 elephants from Carthage to Rome, according to writing by Pliny the Elder," said Angelo Renna."Since then, various plans have been proposed, including tunnels crossing underground and the most recent plan for a single-span suspension bridge, which, if built, would be the longest suspension bridge in the world.""This solution, evaluated alongside different possibilities by the Italian government, is considered the most suitable. However, it does not take into account the environmental impact and the fragile ecosystem in which it will be constructed," Renna explained.Boats can easily navigate between the islands, and trees and vegetation will grow on the artificial pontoonsAs Renna stated, the Strait of Messina is actually located in an extremely seismically active area with strong geological movements and choppy waves. As an important crossing point on their migratory paths, this region is also vital for migratory birds.With a variety of ecosystems and many species that rely on its particular environmental circumstances, the area is also one of the most valuable habitats in the Mediterranean. Additionally, the sea floor is home to a variety of unique flora, such as Posidonia and Laminaria ochroleuca aquatic forests.Boats can easily navigate between the islands, and trees and vegetation will grow on the artificial pontoonsThe architect proposes a submerged floating bridge, sometimes referred to as an Archimedes bridge or a submerged floating tube bridge, in order to build a bridge that enhances rather than degrades the ecology. Based on Archimedes' concept of buoyancy, this design consists of a tube that floats in water.Bird's-eye view of the bridge from Messina Central Station, showing the Calabria coast on the other sideThe tube is positioned 50 meters below the surface, far enough below the surface to not impede water traffic, including cruise ships and boats of all sizes.The 6.0-kilometer bridge is designed to accommodate high-speed trains in the center and automobiles and trucks on the sides. Using mostly unused public domain spaces, the underwater bridge will immediately connect the Calabrian coast at the Campo Calabro highway junction of the E45 with Messina Central Station.Interior view of the tunnel, featuring a bike lane accommodated in the lower part of the tunnelThere is also a bike lane on the bridge's bottom portion. Trees and plants are included into the tunnel's terrariums, improving the crossing's quality. To keep the tunnel from floating up or sinking, metallic frames secure it to pontoons on the water's surface.The idea is for each pontoon, which is 500 meters apart, to be an artificial island that is covered with plants and soil to provide habitat for microbes and birds.The structure's underwater topography is characterized by geometric changes that create inverted hills with peaks and troughs. These regions support ecological diversity in the underwater environment by acting as habitats for a variety of plants, mosses, and invertebrates.Bird's-eye view of the bridge from the Calabria coast on the other side, showing Sicily Island in the background"A submerged floating tunnel has never been built, but several proposals have been made by different entities, starting in 1886, when the naval architect Sir Edward James Reed developed the first concept," Renna explained."Recently, the Norwegian government has been planning to build one in the Fjord to connect different areas of the region.""This bridge typology has significantly less environmental impact because it does not require any anchors at the sea floor and the entire structure can be removed at the end of its life. Additionally, all elements are prefabricated, which reduces construction activities in the water and minimizes harmful effects on aquatic life," the architect continued.Closed view on the artificial islandsAccording to recent research, submerged floating bridges work best in areas with strong seismic activity.As long as the connections with the coastlines include seismic joints, their significant transverse flexibility, along with the extra damping and inertia from water-structure interaction, lessen the amount of earthquake energy transported to the tunnel.Longitudinal section of the entire bridge, with each pontoon spaced 500 meters apart from each otherStudies have also looked into how a submarine collision may affect the tunnel, estimating the possible harm to the submarine and the structure.The outcomes demonstrated that the bridge can manage significant deformation issues. Research on tunnel safety following a collision is still scarce, nevertheless.Aerial photo of the Archipelago bridgeTransversal section. The tunnel is 50 meters underwater.Schemes summarizing main features of the bridgeAxonometric sequenceTimeline the Strait of Sicily:- 251 BC: according to Pliny the Elder, the Romans built a floating structure to transfer elephants from the island.- 1840: Ferdinand II of the Two Sicilies conceived the idea of constructing a bridge, commissioning a group of architects and engineers to provide him with ideas for its construction- 1952: On the initiative of the Association of Italian Steel Constructors (Acai), the American engineer David Steinman was commissioned to draft a preliminary project.- 1969: The "International Ideas Competition for the Stable Road and Rail Link between Sicily and the mainland" was announced, envisioning the construction of a stable double-track railway and six-lane highway in compliance with the regulations of the time. In response to this competition, 143 projects were submitted, including proposals from Grant Alan and Partners; a half-submerged tunnel anchored to the seabed with steel cables, or the Lambertini Group's cable-stayed bridge with three large spans of 3300 meters.- 1985: Prime Minister Bettino Craxi spoke in favor of the rapid construction of the bridge. Stretto di Messina Spa entered into an agreement with Anas and Ferrovie dello Stato (Fs). Subsequently, a new study was published comparing three types of bridges, all proposing a single span, 3.3 kilometers long (which remains the current project idea).-1994:The first government led by Silvio Berlusconi obtained the favorable opinion of Anas and Fs on the newly approved project. However, the project did not commence.- 2011/present: Presented by Eurolink, the two pillars of the Strait bridge will be erected in two different areas with a distance of 3.3 kilometers between them. The opening to traffic is planned for 2032.Top image in the article: Underwater view of the submerged bridge. The underside of the artificial islands serves as habitats for various invertebrates, mosses, and plants, promoting ecological diversity in the underwater landscape.All images Angelo Renna.> via Angelo Renna