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Egg shells, solar cells and availability – that is how the new metro will be sustainable

Steve Persson
The metro is a sustainable and environmentally friendly way to travel, however the extension itself will affect the environment, like all major construction. The object then is to try to make sure that the effect is still as small as possible.

-We want and will be at the leading edge. Sustainability work is about seeing the whole chain. It’s a great challenge to, at such an early stage, consider the whole operating time, that is to say when the subway is finished and the trains have started operating.

This says Steve Persson, sustainability manager at the Metro Extension Administration since last summer.

The metro is built to last at least 100, perhaps 150, years. Because of that the sustainability work is about what is being done here and now and during the construction as well as about how the metro will affect the environment once the trains have begun operating.

- We are going to build an energy efficient facility – that is one requirement that we have, says Steve Persson.

- But how are we going to achieve that? Take for example all of the escalators – how are we best going to cool down the engine rooms underneath them? Are we going to use natural cooling from bordering tunnel spaces? Or perhaps an air heat pump? And if so, can be it run with solar cells?

Solar cells on the roofs on the future metro entrances is a particular feature in the planning and is something that may be possible to build, even though it is not clear at the moment how it will be done and how they will be used. A way to secure the construction for the future.

We need to think big
The greatest environmental impact comes from all of the material that is required to build the metro – primarily the cement. The idea then is to think big in order to come up with solutions for how one can use a smaller amount of cement.

- One thing that we’re looking at is how we can mix in other materials in the cement and still maintain the same quality. For example, there is a mixture of ashes from thermal power stations and eggs shells, Steve Persson explains.

However, the most important aspect in decreasing the amount of cement is the ambition to make the facility as small as possible, without compromising when it comes to quality. The smaller the tunnel is the less concrete is needed and the less rock masses need to be removed. It also becomes cheaper to build.

- It is a very good ambition in every way – although at the same time we can’t minimize everything too much. We still need to build safe platforms with a good overview, and naturally everything will be accessible and the staff who will be working in our services areas need to have a safe work environment, says Steve Persson.

At the moment there are intense preparations under way in the entire administration for the construction start next year. Steve Persson and his team are working on adding sustainability requirements to the upcoming procurements.

- We need clear requirements regarding sustainability, which can also be calculated for the contractors. Because during the construction time we will need committed and competent contractors and a strong drive from us as constructors. These issues need to be integrated into everything we do, concludes Steve Persson.