A key milestone has been reached in the construction of Finland’s longest and tallest bridge. The bridge is 1.2km long and has a 135m tall supporting pylon.
A key milestone has been reached in the construction of Finland’s longest and tallest bridge. New Civil Engineer reports that the Kruunusillat (Crown Bridges) scheme in Helsinki is designed to link the new island suburb of Laajasalo with the city centre of Helsinki. The cable-stayed bridge is 1.2km long and has a 135m tall diamond-form supporting pylon.
The pylon construction has now been completed, and it will support two 250m long cable-stayed spans. The diamond-shaped design of the pylon serves a structural function, and is also a nod to the historical crown ownership of the Helsinki Bay area. The bridge will not be open to vehicular traffic, but will carry light rail, cycle, and foot pedestrians.
This is a deliberate design strategy to move towards a car-free city centre by 2030, and reduce CO2 emissions and meet sustainability targets.
The bridge was designed by Knight Architects following an international design competition. Their director Tom Osborne said: “We have been working on Kruunusillat for over a decade, so it’s fantastic to have reached this critical milestone in its delivery.”
“The distinctive diamond now provides Helsinki with an instantly recognisable addition to its skyline, that we hope soon comes to symbolise not only the identity of this wonderful city, but its continued efforts to shift to sustainable transport modes.”
He added: “At Knight Architects, we strive to design bridges that do much more than just connect A to B. We aim to create beautiful structures that respect and enhance their environment and generate lasting value, and Kruunusillat is a great example of that approach in action.”
What is a cable-stayed bridge?
A cable-stayed bridge is a type of bridge where the deck is supported directly by cables connected to one or more supporting towers or pylons. The cables run diagonally from the tower to the deck, creating an aesthetically pleasing fan or harp pattern. The towers or pylons bear the majority of the structural load.
Cable-stayed bridges are commonly used for longer spans of between 500ft to 3,300ft. This is partly because they require fewer materials, as the cables are the key supporting feature rather than the anchorages. They can also be built in sections without the need for underlying support, which makes the construction process quicker and easier.
The easier construction is a particular advantage when the bridge is passing over deep water such as straits, rivers, and seas, or deep valleys. The bridges are very strong and stable due to the even distribution of weight, and are designed to withstand high winds and a strong degree of seismic activity.
What is the world’s longest cable-stayed bridge?
The Changtai Yangtze River Bridge in China is believed to be the world’s longest cable-stayed bridge. The bridge has a span of 10.3km, and has separate sections for road vehicles and trains. The construction process took five years, and it’s set to fully open in April 2025.
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