It is now more than twenty years since a proposal was first mooted to hold an international tunnelling symposium in Britain. At the time of the first symposium, held in London in 1976, the Channel Tunnel pro­ ject had just been shelved. Last weekend a charity walk was held in the finished tunnel, which will be open for business later in the year. Tunnels have figured prominently, and at times spectacularly, in the development of national and international links and it is hoped that such links gather pace in the future. It is particularly pleasing that Alastair Biggart of Storebrelt has agreed to deliver the twenty-sixth Sir Julius Wernher Memorial Lecture of the Institution of Mining and Metallurgy, entitled 'The changing face of tunnelling', at the start of this event. * Although almost every edition of the technical journals on tunnelling reports another £1 billion scheme somewhere in the world, it would be unfair of me to suggest that tunnelling is restricted to these prestigious schemes for major transport links. Much of the work that makes mod­ ern life possible receives hardly a mention outside the technical press and one suspects that society at large applies the 'out of sight, out of mind' attitude even more readily to underground construction than it does to other forms of engineering. Clearly, there is a contiiming need to improve the capacity and performance of our infrastructure, while hav­ ing a careful regard for the environment.

Hydropower.- Lesotho Highlands Water Project: design and layout of underground works for 'Muela Hydropower Project.- Design and construction of the cooling water intake tunnel system for Point Aconi generating station, Nova Scotia.- Comparison of two classification systems as applied to the Alpe Devero tunnel, Italy.- Metro/Rail.- Planning and design of tunnels for the Jubilee Line extension, London.- New St Clair River tunnel, Canada-USA.- Application of NATM to design of underground stations in London Clay.- Water/Waste.- Underground works on Third Nairobi Water Supply Project.- Design and construction of caverns for an underground sewage treatment plant, Hong Kong.- The Snake: a rock tunnel for storing combined sewage water, Stockholm.- Tunnelling on the Penzance and St. Ives sewerage scheme, Cornwall, England.- Tunnel-boring Machines.- Two tunnel-boring machines for Lesotho: a design and case history.- Open TBM tunnelling in complex geology for railroad in Sweden.- Use of sedimentary rock impact indices in evaluation of tunnel-boring machine performance.- Development and performance of tunnel-boring machines on Phase II of the London Water Ring Main.- Environmental Issues.- Environmental planning for the Massachusetts Water Resources Authority's MetroWest water supply tunnel.- Palais Bernheimer in Munich: tunnelling for parking space under a historic building.- Limiting the damage to historic buildings due to tunnelling: experience at the Mansion House, London.- Compensation grouting to limit settlements during tunnelling at Waterloo Station, London.- Ground movement model validation at the Heathrow Express trial tunnel.- Case Histories.- Gjøvik Olympic Mountain Hall, Norway.- Construction of new escalator shaft and passageways at London Underground's Waterloo Station.- Water in TBM drives, Delivery Tunnel South, Lesotho Highlands Water Project.- Tunnel-boring Machines.- CEN safety standards for tunnelling machines and air locks.- Tunnels below waste disposal tips.- Machine tunnelling in the northwest of England.- EPB-shield tunnelling for the Taipei Metro, contract 201A.- TBM drive management by use of computerized systems.- Research.- Long-term measurements of loads on tunnel linings in overconsolidated clay.- Non-destructive investigation of tunnels.- Case Histories.- Design, construction and performance of a 700-m 'cover and cut' tunnel in soft clay, Norway.- Shotcrete in the construction of Pen-Y-Clip tunnel, North Wales.- Face support for a large Mix-Shield in heterogeneous ground conditions.- Design.- Tunnel ring design, development, testing and manufacture for the London Water Ring Main.- Medway tunnel detailed design.- Developments in precast concrete tunnel linings in the United Kingdom.- Case Histories.- Channel tunnel: French undersea crossover design and construction.- Design and construction of Metsovon road tunnel, Greece.- Construction of the 'Passante Ferroviario' link in Milan, Italy, lots 3P, 5P and 6P: excavation by large earth pressure balanced shield with chemical foam injection.- Pen-Y-Clip road tunnel, North Wales: achieving a dry lining through a pervious rock formation.- Hydropower.- Tunnel design in the design and construct context-the Pergau experience, Malaysia.- Serra da Mesa project, Brazil: excavation of shafts and penstocks.- Tunnel Machinery.- Rock cutting with roadheaders.- Increased productivity in construction of civil and mining tunnels through the use of high-capacity tunnel-boring machines and continuous belt conveyor muck haulage.