Geology Reference
In-Depth Information
Sometimes the contractor might identify some better or more cost-
effective way of carrying out part or all of the works and can offer this
as an alternative design to that presented in the tender documents (the
conforming design); the owner might accept this proposal because of
price, programme or quality reasons. The contractor (and his designer)
might then take over responsibility for future design works and the
owner may employ another engineer to check these designs.
The contractor may sub-contract parts of the works
for example, by
employing a specialist piling sub-contractor to construct that element of
the foundations. Whilst for a normal engineer-design project, the
consulting engineer is responsible for overall design, the contractor
may need to design temporary works necessary as intermediate mea-
sures in achieving the
-
final design intent. For example, to construct a
deep basement, the contractor may have to design some shoring system
to support the excavation until the
final walls and bracing slabs of the
final structure have been completed. Temporary works should nor-
mally be designed to the approval of the engineer. In some instances,
some of the permanent works are designed by the contractor or the
temporary works somehow incorporated within the permanent works
because to remove them might be too dif
cult or it is otherwise
bene
cial to do so.
Contractor
s designs are sometimes adopted for parts of a project
because of his local and specialist technical experience together with
his knowledge of the costs of material, plant and labour. Another
advantage is that there may be less ambiguity in terms of who is
responsible for the performance of the works and in particular dealing
with problems posed by dif
'
cult ground conditions. When it comes to
foundations or tunnels, the contractor should be in a position to accept
the risk of any unforeseeable ground conditions
providing he is
allowed to design and conduct an adequate ground investigation to
his own speci
-
cation.
For many large projects, an independent checker is employed by the
owner to give added con
dence that the design of permanent and
temporary works is correct. The checker is usually a similar type of
company to the design company, i.e. an engineering consultant. The
check could be con
ned to a simple review of design assumptions
and calculations but, in some instances, might involve a comprehensive
and separate analysis of all aspects of a project.
Civil engineering is a commercial business and the engineering geolo-
gist needs to understand how it works. The relations between all
