The nature conservation association Helsingin luonnonsuojeluyhdistys has made a proposal to protect the bridge under the Act on the Protection of the Built Heritage, and the Centre for Economic Development, Transport and the Environment for Uusimaa has therefore issued an endangerment prohibition on demolishing the bridge. Demolition of the concrete vault of the bridge had not started when the endangerment prohibition was issued.
Old concrete structure in very poor condition
Located at Pohjoinen Rautatiekatu, the Mannerheimintie bridge was built in the late 19th century. The bridge passes over the Baana bicycle route. The Mannerheimintie renovation project is intended to include the replacement of the bridge’s concrete vault structure, which is in poor condition and does not meet today’s load capacity requirements.
“Unfortunately, condition surveys and sampling revealed that the old concrete vault cannot be reliably repaired, which is why we have decided to replace it,” says Riku Kytö, bridge construction expert and Project Manager at the City of Helsinki.
The existing stone foundations and stone façade of the vault are in good condition and will not be altered, but they will be restored as part of the renovation. The new bridge will therefore rely on the old foundations, and the original stone façade will be preserved.
The new concrete vault structure to be built is similar to that of the bridge built in the late 19th century. However, the new concrete vault will be reinforced to better withstand the loads caused by current and future vehicle and tram traffic.
Helsinki City Museum involved in planning the renovation
The Helsinki City Museum has provided guidance on the planning of renovations, and the historic nature of the bridge has been taken into account in the planning.
“This is one of the oldest non-reinforced concrete bridges in Finland. The structure is part of a significant urban landscape and cultural environment. It is important that the shape, foundations and stone facing of the bridge remain unchanged despite the renovation of the concrete structures. The City Museum also provides instructions on how to document the original vault structure of the bridge in connection with the work,” says Reetta Heiskanen, Director of the Helsinki City Museum.
Impact on the bridge repair schedule will be specified later
According to the preliminary estimate received from the Centre for Economic Development, Transport and the Environment, processing the proposal submitted by the nature conservation association and making the necessary statements will take several weeks or months. If the processing of the endangerment prohibition is delayed, it is possible that there will not be time to repair the bridge as part of the Mannerheimintie renovation project and it will have to be repaired later.
