أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
This approach means that the bills used in tendering are approximate in content,
although representative of the project. The whole of the works is remeasured as
executed, but priced at the rates in the original bills, or rates derived from them. The
method is useful when the conditions just indicated apply, that is, uncertainty
initially. It is particularly helpful when time is tight, because it saves on pre-contract
time and allows overlapping between design and construction. It tends to higher
pricing by tenderers, as there are uncertainty factors about the reality of the quantities.
This is not something which is entirely resolved by the final remeasurement
producing the correct quantities. Tenderers must always price quantities with some
regard to which items are for larger or smaller parcels of work, which affects their
interaction, the use of common resources and other organisational and programming
matters. Even though these conditions are taken into account in settlement to a
degree, a margin still tends to be allowed.
Approximate quantities undoubtedly save time, although how beneficial this is will
depend on whether design then keeps ahead of construction. They may, as a
byproduct of this, allow options to be kept open until a later date. Because they are
less precise, they do not offer the same cost control, but this may be obtained from a
good cost plan or other control estimate set alongside the bills and remeasurement
and modified in price level in the light of these data. If firm quantities are subverted
by extreme variations, their control value is often lost.
The degree of approximation has no strict limit and may be conditioned mainly by
time or information available. It is possible to base bills on quite close design, saving
a margin of time by somewhat loose attention to accuracy. At the other end of the
scale, it is possible to produce bills by starting from broad estimates of cost based on
sketch drawings and a reasonable indication of the type of construction and materials.
The actual quantities are then produced by dividing up the estimates and feeding in
detailed item descriptions and quantities which are anticipated as a result. There is
never any virtue in greater approximation for its own sake, but much can be achieved
when needed. It is always necessary to describe the site conditions, character of the
works and other overall features fairly accurately, so that overheads and general price
frameworks are not thrown too far out.
So far as fees go, firm quantities with extensive variations are likely to cost about the
same as approximate quantities with remeasurement. Often approximation should be
used as more realistic in all the circumstances.
