Civil Engineering Reference
In-Depth Information
the soil: the soil risk was contractually laid down with the contractor whereby
a number of specific matters in this arrangement are excluded. In a project
such as the construction of the Westerschelde Tunnel, the soil which is bored
through is an important source of uncertainty and any obstacles in the ground
to be bored through form an important matter for concern. In the neighbour-
hood of Terneuzen there was for example the possibility of a primeval forest
of which the petrified remains might possibly cause problems. Old ship-
wrecks, erratic boulders or old foundations could also block the tunnel boring
machines with all its consequences. Smaller obstacles could be removed but
man-made objects in the soil larger than 0.5
0.5 metres could result
in lengthy delays and possibly even in the loss of a tunnel boring machine.
This uncertainty can be translated into either additional (cost-increasing)
facilities which the contractor provides, or into liability afterwards due to
unforeseen cost-increasing circumstances. In order to limit the costs for the
client, it was advisable to have a more detailed soil investigation carried out
by the contractor and to share the soil risks between the parties as explicitly
as possible.This also happened during the negotiation process from the first
offer right up to the final contract.
0.5
Fig. 17.2
Inside the IBM
Experiences
General
The expected advantage of a good integration between design and imple-
mentation which should result from the design, build and maintenance con-
tract, did not live up totally to its promise. In fact there was little difference
from more traditional ways of working.The reason for this is that various firms
of consulting engineers were engaged for the design work and the implemen-
tation for a large part was usually undertaken by subcontractors that set
to work with or without an invitation to tender. Various subprojects were
concerned (design, concrete production, roads, tunnel, operation and suchlike)
which indeed contractually connected to each other by the main contractor but
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