Construction of the Raide-Jokeri light rail line connecting the cities of Helsinki and Espoo has been suspended due to concerns that the work could damage the diverse natural habitat of the Siberian flying squirrel and other wildlife.
The Supreme Administrative Court of Finland (KHO) ordered the felling of trees in the suburb of Pajamäki to be stopped after the court upheld a complaint made by the Helsinki Nature Conservation Society (Helsy) in July.
Helsy and the local suburb association of Pajamäki said that the felling project – which calls for at least 400 trees to be cut down to make way for a Raide-Jokeri tunnel – violates Finland's Nature Conservation Act.
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"It's a shame they're building the tunnel right next to the Patterimäki hill," said local Pirjo Laiho, adding that an alternate route should be possible that wouldn't disturb the natural ecosystem.
Helsinki's zoning board chief Tuomas Hakala responded to the criticism by saying that an environmental survey has deemed the tunnel to be the best solution.
Construction of the tunnel is set to resume in spring 2020, when KHO will make a final ruling on the conservationists' complaints.
The new light rail service from Itäkeskus in eastern Helsinki to Keilaniemi in Espoo is set to cost 275 million euros upon completion in 2021. The costs will be split between the two cities and the Finnish government.
Expert: Conservation to increasingly hamper construction
The Pajamäki area is home to a variety of animal species such as foxes, weasels, birds – and the rare flying squirrel. The small mammal is constantly making new inroads into Helsinki's lush suburbs.
Helsy spokesperson Laura Kuivalainen said that razing the old trees in which the squirrels build their nests is irresponsible.
"The city views hundred-year-old forests as little more than worthless building sites," she said. "Maybe we should consider following Sweden's example. Construction work in Stockholm avoids natural locales."
Kuivalainen said that efforts to conserve the flying squirrel's home turf are increasingly likely to conflict with the city's zoning plans in the future. Ilpo Huolman from the local Centre for Economic Development, Transport and the Environment (Ely-keskus) agrees.
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"There are several Helsinki zoning plans in the works that will need to be reconciled with the needs of the environment. The natural value of potential construction sites must be evaluated much more carefully."
But even with more rigorous assessments, Huolman said, flora and fauna may develop in surprising ways that could require building crews to change their tactics.
While flying squirrels are a relatively new concern in the capital, the city of Espoo has taken steps to better understand the creature and its habits some five years ago.
Environmental specialist Laura Ahopelto said that existing data on flying squirrels is always consulted when designating construction zones, and that radio collars will next be used to gather more accurate information. Ten squirrels are soon to be tagged.
"We will gain great insight into the routes and territories used by the flying squirrels, and how they choose to cross large highways," Ahopelto said.