Counting carbon, and more

The theme is increasingly prominent around concerns of climate change and the desire the shrink the carbon load that is generated when producing construction materials, such as cements traditionally and commonly used in concrete. As concrete in different forms is a common factor in tunnel design and construction, more efforts are being made to lighten the carbon loads of such materials.

Some of the efforts and thinking are discussed in the technical focus on concrete in this issue.

Also on matters of concrete – and its use on a huge scale – this issue of T&T also has images of the large-scale steel formwork now onsite in Denmark to cast the many heavy segments that will make up the world’s longest immersed tube tunnel. While big in themselves, they are swallowed by the dedicated precasting factory built for the Fehmarn project that will link to Germany.

Founded upon years of planning, the construction effort is taking off.

The need for greater early focus on pre-construction planning, and consequently de-risking, is also a feature of guidance issued by ITA on preparing for spoil management, whatever the type of tunnelling activity. The guide draws upon lessons from a number of projects, especially in the US and Italy, and builds upon earlier work by the ITA. Key points from the guidance report are reviewed.

The other side of what comes out of the ground is what goes in, and this issue carries two features with quite different thinking on where and how to place nuclear waste underground for safe and secure long-term storage.

Once again, we are also pleased to carry a runner-up paper from the most recent BTS Harding Prize Competition. The paper discusses research findings on grey cast iron linings, which are so common in the older metro (‘Tube’) tunnels in London, and presents new structural insights.