Tunnelling Contracts and Site Investigation

In recognition of the importance of site investigation for ground engineering works, and the need for site (ground) investigation specialists to be aware of the contractual significance of their results and interpretations, the writer began work in the early 1980s on two areas of the subject: first, a survey of UK tunnelling contracts and associated site investigation costs, and, second, a review of the place of site investigation in tunnelling contracts. The impetus for the work stemmed largely from the major tunnelling activity in the north-east of England and particularly on the Tyneside Sewerage Scheme which is now substantially completed. The former work was reported* and circulated to those companies that had responded to the request for information, and was also made available to other enquirers. A significant feature of the analyses was the manner in which all the cost data on tunnelling contracts and their site investigations were recalculated to a
common base date, so allowing realistic conclusions to be drawn as to the cost effectiveness of the investigations. Statistical packages were used to resolve trends between geological, geotechnical, geometrical and cost data. Several earlier, quite short, and unpublished versions of the latter review were produced as a private initiative and circulated in a limited manner within the industry. The project was then put on the ‘back burner’ until in late 1989 when, realising that many site investigations for tunnelling works were being conducted without a firm understanding of the contractual problems
which could ensue, the writer decided to revise and considerably expand the text.