By placing the majority of the road in tunnels, roughly 18 of the 21 km, residents and natural and cultural environments are protected to a major extent.
18 km in tunnels reduces the impact on the environment
Of the E4 Stockholm Bypass's 21 km, roughly 18 km are in tunnels in order to minimise the impact on residential areas, nature and cultural areas. The Stockholm Bypass passes below or through six natural or cultural reserves, including several of national interest, including the world heritage site Drottningholm on Lovö.
With a tunnel solution, the Swedish Transport Administration has successfully minimised the disturbance of Lovö and the Grimsta nature reserve. A tunnel extends for approximately two kilometres under Järvafältet and Igelbäcken.
E4 Stockholm Bypass and climate goals
According to climate goals, emissions in Sweden should be reduced by approximately 30 per cent by 2030 in comparison with 1990 levels. The E4 Stockholm Bypass is estimated to account for less than 1 per cent of emissions from road traffic. The increase of carbon dioxide emissions for which the E4 Stockholm Bypass accounts thus makes it neither easier or more difficult to achieve the climate goals.
With various fees and taxes, such as the congestion tax on Essingeleden, in combination with good community planning, it is possible reach the goals.
Air quality and noise
Reduced traffic volume on approach roads, in central Stockholm and on Essingeleden mean that noise and exhaust gas will be reduced there when the Stockholm Bypass is finished.
On the short stretches where the route goes above ground, the Swedish Transport Administration is implementing noise-reduction measures. Noise protection means will also be installed in order to reduce the noise levels in recreational areas and in nature and cultural reserves.
Research to establish guideline values for tunnel air
One challenge that must be mastered is the tunnel air. Exhaust gas from the cars can be managed in different ways, primarily with good ventilation. Three air exchange stations are planned in each direction along the tunnel to improve the air quality inside the tunnel.
The Swedish Transport Administration finances research for the purpose of assessing the health effects from the tunnel air and will then serve as a basis for identifying guideline values for the tunnel air. Research has shown that cars and buses are much more efficient than we previously though with respect to keeping out harmful air pollution. The problems associated with particles stirred up by studded car tyres are also much less substantial than we previously assumed.
The research is progressing rapidly and the project will continue to follow the development in regard to health research and engine combustion, fuel and emissions.