The future will throw up many intractable problems for tomorrow’s politicians, lawmakers and economists to solve. The way they do this will have incalculable consequences for the future of our crowded planet. The underground – the so-called ‘fourth dimension’ – will become increasingly more valuable as space on the surface becomes scarcer. The infrastructure requirements of the mega-cities and the developing regions of the world will have to be met as populations rocket and the need to protect the environment becomes crucial for our survival. Even the moon and other planets may be co-opted as we desperately strive to save our own (see box).

Here on Earth, we shall soon have more automatically controlled cars on our roads. Sensors will warn drivers when they are passing too close to other cars or to tunnel walls. Such a system could also ensure there is enough distance between cars, lorries and trucks in the event of a traffic jam in a tunnel. Vehicles stopping bumper to bumper compounded the risk in the Mont Blanc and Tauern tunnels during the two recent catastrophies, enabling the fire to pass from one vehicle to another and contributing to the horrifying outcome. In the near future, guidance systems will be able to warn the driver long before he is entering a tunnel or a specific section of road and recommend alternative routes.

The speed of trains in long distance train systems will increase, prompting the need for more tunnels. Mass urban transport will become more and more automated and remote controlled; first steps have already been taken with the VAL-System in Lille and METEOR in Paris, and the Docklands Light Railway in London.

Developing the underground to incorporate weather proof shopping malls, cultural and sports facilities, housing, offices, car parks and walkways, aiding the movement of people by installing conveyor belts like those at airports, will become more commonplace. Radically extending the uses of the underground will allow scope for the surface to be devoted to improving the quality of life by reducing pollution and upgrading urban landscape by introducing more parks and pedestrianised walkways.

The trend towards the multi-purpose use of the underground can be observed on every continent (except Antarctica). In Europe, there are over 10 000km of traffic tunnels in operation today, and many more under construction. In Germany alone, the average annual production rate for the last ten years has been 12km for metros, 5km for railways and 11km for roads. Similar figures are available in other parts of the world.

Tunnelling technology will continue to develop. Trenchless solutions for service and disposal lines will become more and more crucial and will help to protect the environment and conserve historic city architecture. For transport tunnels, with their larger cross sections, construction techniques are bound to improve during the next few decades. The tendency towards ever increasing cross sections for larger tunnels will continue and the mechanisation of tunnelling will progress. The 14.2m diameter TBM for the fourth crossing of the Elbe River in Germany will not be the benchmark for long. Plans under development in, for example, Japan and Germany are already extending excavation diameters to 15-16m. The highly sophisticated ground investigation methodologies employed over a distance of 30-50m ahead of the face will be improved and be more and more generally applied. Furthermore, robotics will develop significantly in the field of excavation and lining placement.

&#8220We must beware of over-estimating our engineering abilities and under-estimating geological and methodological uncertainties in our underground activities”

Even conventional tunnelling has not reached its limit yet: more sensitive explosives and ignition methods will be developed to avoid impacting on adjacent rock and on the surface. All these developments will contribute to safer tunnelling, better occupational health conditions, less disruption on the surface and reduced risks during construction.

Not fantasies but facts

Another field in tunnelling will acquire more and more importance: linking neighbouring countries and continents. The alpine countries are to excavate mega tunnels which are 50-60km long (the Gotthard, Lötschberg, Brenner and Mont Cenis base tunnels). Straits crossings between Europe and Africa (Gibraltar Tunnel) or Asia and North America (Bering Strait Tunnel) etc. are no longer fantasies but feasible projects.

However, we should never underestimate the risk of taking too many steps at once. We must beware of over-estimating our engineering abilities and under-estimating geological and methodological uncertainties in our underground activities. Planetary tunnelling is not our concern at present; there are still too many problems to solve on Earth.

If we do so, we will be able to bequeath a functioning world to future generations, and, in the process, to fulfil the objectives of the International Tunnelling Association and its member nations around the world.