Green tunnels for Stockholm

Implenia is building two tunnel sections for Stockholm’s new city bypass. Work started in autumn 2016. Because the route goes through a sensitive lakeland area, Implenia Sverige has had to implement complex environmental measures.

A new 21-kilometre-long main road is being built to relieve bottlenecks in the transport system and take traffic out of Stockholm’s city centre. Implenia is responsible for an important part of the project, centred on the Johannelund construction site. This impressive section consists of two 3.6-kilometre long, three-lane tunnels with four entry and exit ramps. There are also four ventilation shafts and 60 cross-galleries, rescue tunnels and access shafts.

Implenia started blasting the tunnels in October 2016. Around 1.5 million cubic meters of rock will have to be excavated in total. Meanwhile in Lunda, Implenia has been building two 1.6-kilometre-long road tunnels for the same bypass project since spring 2017. According to the plans, all of the tunnels will be open to traffic in 2026.

At both construction sites, the drilling and blasting work beneath such a densely populated area presents major challenges, as does the management of noise emissions and site logistics. What is more, a good part of the route runs beneath Lake Mälaren, Sweden’s largest drinking water reservoir.

Implenia Sverige is determined to complete the projects to the highest sustainability standards. The company has, for example, installed a state-of-the-art water treatment plant, which cleans process water from the tunnels and pumps it back into the cycle. The aim is to recycle 80 percent of the water used in the project.

CO₂ emissions are another priority. Implenia wants to keep greenhouse gas emissions as low as possible during construction and beat the target set by the client by 10 percent.