The challenges can seem to be constant and stacked. The nature of things. Puzzles to be solved. If it were only engineering involved that might be fine for most working in tunnelling, for those types of interests are what drew in many to civil engineering, or mechanical, or of course mining.

The engineering efforts pursue competent designs, then get to digging, to bringing the concepts into reality, to fit how the ground it is found to be, below the surface.

Challenges. When overcome, celebrations are rightfully held.

But engineers do not exist in isolation. The less exact sciences play roles in tunnel projects, too – in demand estimates, and cost-benefit analyses, and ways to pull funding together, plus ideas for procurement, or types of contracts, and measuring and monitoring, and on, and on. There is much ado in making a project.

Repeat that for projects, making up portfolios of assets to be built for large owners. Or even splitting up large single jobs into different lots, or packages, and handling them slightly differently.

All in all, there are many different players that will come together for a project: on the client side, and for governance – even including politicians, while they last in post; and, of course, the many companies collaborating in the supply chain.

With so much talk and effort, there is much then to celebrate upon completion of a tunnel, large or small. But getting there, with all those interfaces and relationships and variables, and different perspectives on risk, of all shades, can feel a long road. But well walked, hopefully. Ideally.

In this issue we look at celebrations on many tunnel completions, and take note of challenges raised, and the opportunities to add and share knowledge, to improve sustainability on the way, and the many possibilities still to develop so much in underground space.