Urbanisation has long been a fact. Cities are spreading out over good agricultural land, areas of unstable ground, the bottoms of old lakes, and over green spaces during urban densification. To an increasing extent, cities are becoming vulnerable systems. They can be easily exposed to landslides and flooding. At the same time, traffic is increasing. The environmental problems are comprehensive and concern health, waste disposal, pure air and clean water. Structured planning of natural and energy resources is necessary. Issues regarding land use are of key importance for the development of infrastructure, construction and industrial activity. In densely developed areas there are evident trends today to expand upwards. Since there is only limited space for expansion, underground construction will greatly increase. Our rocks will be increasingly used for transport, storage spaces, parking areas and garages. This is already happening in some cities in Sweden and in many other countries.
Ongoing infrastructure projects
There are several examples of finished, ongoing and planned infrastructre projects in Sweden in the vicinity of the areas where the population is expanding.
- in Stockholm: Southern and Northern Links, the Outer Transverse Link, the City railway, expansion of the transverse tram system and burying of cables in rock tunnels, Stockholm Bypass
- in Göteborg: Göta Tunnel, Northern and Western Links, Kringen, and
- in the Malmö Region the large City Tunnel project adjacent to the Öresund Bridge
To an increasing extent, major infrastructure projects may also affect other populous areas.
Soil, rock and water
Urban underground construction imposes very great demands on technical know-how and experience in planning and implementation. Attention must be paid to the complex geological, hydrogeological and rock mechanics conditions, and to the disruptions and points of conflict that arise in conjunction with existing installations below ground and with the intact street and living environment. Urban construction thus imposes great demands on knowledge of conditions below ground. Geotechnical and other investigations are needed for increased knowledge of geology, geotechnics, rock mechanics, hydrogeology and material properties both in the ground and in adjoining areas. Multidimensional modelling is an important and necessary tool for the assessment of risks. Several problem areas can be identified: water, reinforcement, drainage, maintenance, training and life cycle costs.
New investment in research
Last autumn, researchers from Geological Survey of Sweden SGU, Swedish Rock Mechanics Research Foundation Befo, Swedish Building Industry Development Fund SBUF and Swedish Geotechnical Institute SGI met representatives of industry, the authorities and clients at a workshop at Formas to discuss urban environment and underground construction.
The discussions during the workshop were dynamc, and many proposals and views were put forward. It was agreed that there is a great need of broad based and sustained research and development activities in the near future. In spite of valuable inputs by several former r&d programmes, intensified and sustained r&d is now needed, one of the reasons being to avoid large additional costs – due to inadequate knowledge – in the large expansion of Swedish infrastructure which has begun and will continue on a large scale.
The inputs should be considerably larger and more sustained – programmes that extend over a long period – than had been the case before. Research programmes should have an overarching focus on sustainable development and climatic adaptation, consideration and reduction of greenhouse gases. Important issues are
- Water and its interaction with rock and soil
- Safety and forecasts, comprising a risk analysis, working environment, preliminary investigation methods etc
- Operation and maintenance
- Effectiveness – here in a very broad sense that includes many subgrops; see the text below
- Logistics and material supply
At the time of writing, work is in progress on starting a powerful and long term research programme, GEOINFRA. Its focus and scope have broad support in the research world, the industry with contractors and clients, the agencies who have to consider the problems, and several funding institutions. The above five broad research areas should be developed in a long term (6 years) research and development programme with the associated inputs for knowledge provision and experience feedback. A broad circle of funding institutions is desirable in the proposed continuation of the work, to be carried out from this year up to the summer of 2011.
The research inputs are characterised by the following:
- A broad based research programme with partly new consortia of contractors, which requires a soft start and a soft termination phase. The programme should have a temporal extent that permits radical research inputs with a clear focus on macroeconomic savings. It is essential to enhance knwledge before the large investments are made in infrastructre – this is macroeconomically profitable.
- It should be possible to start the activities in the programme with a reasonable volume without waiting until all funding institutions have reached a decision whether to participate.
- This research will be a good complement to other inputs in the urban environment.