Mitigating the environmental impacts of transmission lines
Changing the landscape
Transmission lines always give rise to changes in the landscape, and transmission lines placed in new terrain are often considered especially disruptive. In covered areas of terrain, transmission lines may only have a localised impact on the landscape. The most significant impacts on scenery can occur when transmission line towers are erected in open landscapes, elevated terrain or at important junction points in the landscape. It is particularly important to plan the placement of towers in the immediate vicinity of yard and garden areas and other challenging private property.
The impacts of new transmission lines on the landscape and the opportunities to mitigate such impacts are studied as part of the environmental impact assessment.
Land use restrictions
In general, transmission line rights-of-way must not contain buildings or structures, and any actions taking place in such rights-of-way must not jeopardise electrical safety. Transmission line projects may indirectly affect the locations and directions in which land use can be expanded.
In fields, transmission line towers and supporting structures may disrupt the use of agricultural machinery and increase the spread of weeds. In forestry areas, the forest land under transmission lines can no longer be actively used for forestry work. The transmission line area can be used for recreational purposes, such as hiking and berry picking. For further information about using transmission line rights-of-way, see (link to the page on using transmission line rights-of-way).
Impact on nature
The principal for designing new transmission line routes is to avoid disrupting important natural sites. Nature values are studied during the project planning phase, and care is taken to ensure that nature is conserved during the construction phase by issuing site-specific instructions. The impacts are mitigated through the careful placement of transmission line towers, scheduling work correctly, and installing markings to reduce the risk of bird collisions in sites with lots of birdlife. Permanent impacts on nature mainly arise at new tower sites, in rights-of-way that need to be cleared and kept open, and in the boundary zones of rights-of-way that are treated regularly.
Transmission line construction also has positive effects on biodiversity. Thanks to regular clearing, rights-of-way that are kept open can act as substitute habitats for species suffering from the decline in meadowland and traditional habitats. For example, a transmission line right-of-way in Pirkanmaa has been treated in order to protect endangered false heath fritillary butterflies (Melitaea diamina). Sheep have been allowed to graze in a transmission line right-of-way in Nokia, revitalising disappearing meadow species. The rattle grasshopper (Psophus stridulus) is an example of a rare species that thrives in the sunny and dry habitats prevalent in transmission line rights-of-way. When drainage ditches are dug, transmission line rights-of-way can also offer alternative habitats to marsh butterflies and plants that are at risk.