The city of Helsinki, Finland, has added another milestone to its array of architectural attractions with the recent opening of the Kruunuvuorensilta, the country’s longest and tallest bridge.
Part of the Crown Bridges Light Rail project, a three-bridge, $378 million program to link Helsinki’s city center with the fast-growing Laajasalo district, the 1,200-meter-long cable-stayed structure with its 135-meter (443-foot) high diamond-shaped pylon is designed exclusively for public transport and cyclists. Recent studies indicate that private vehicles account for only 18% of all trips in the city. A vertical main channel clearance of 20m will preserve passage for most sailing vessels.
Due to be completed in early 2027, the Kruunuvuorensilta tram line will be part of a 10 kilometer system connecting central Helsinki with Laajasalo, which is expected to double in population over the next two decades.
The construction of the $142 million Kruunuvuorensilta, designed by the UK-based team of Knight Architects and WSP Finland, was carried out by the joint venture of Finnish construction companies YIT and Kreate Oy. The four-year effort, which included the two-year concrete casting of the pylon, was itself a model of sustainability, with the use of low-emission materials and renewable energy sources. The total carbon footprint is approximately 129,000 tonnes of carbon dioxide equivalent, of which 76% comes from construction and 24% from operation and maintenance over a 50-year period. Helsinki is working towards a city-wide goal of net zero carbon by 2040 and carbon negative thereafter.
“Bridges of this size are rarely built exclusively for public transportation, pedestrians and cyclists,” Knight Architects stated in a press release.
Creating a distinctive bridge with a design life of 200 years proved equally challenging, given the demanding landscape and coastal location of Helsinki which results in exposure to a wide range of weather conditions. The tin cables of the structure are designed to stay in a constant slight movement in the wind, helping to prevent ice formation. Ice build-up is further reduced by enclosing the cables in textured plastic sheaths that break the ice into fine particles. Other features include a wind warning system, with high wind alerts displayed on light boards at both ends.
Other features include a generous and clearly organized deck that offers wide, legible routes that allow for intuitive movement for pedestrians and cyclists; a curved alignment that allows users to see their destination ahead, reducing the “vanishing point” often found on straight bridges; and a “family” of three parapets that maintain a high-quality and consistent pedestrian experience, protect from prevailing winds and maintain views.
The Crown Bridges programme, which began construction in 2021, has also included improvements to streets and public services along the route, including the replacement of an existing vehicular crossing in Helsinki city center to remove ramps and improve accessibility for pedestrians and cyclists.
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