Civil Engineering Reference
In-Depth Information
The application of standard components is reasonable because of economic rea-
sons as their wider usage implies higher quantities and this, in conjunction with
pressure from inter-companies' competition, results in reduced cost. In order to
make standard components from different suppliers acceptable, they must be com-
patible and functionally homologous. That is, what standards shall guarantee? Un-
fortunately, it is not a self-fulfilling prophecy ensuring that different suppliers pro-
vide identical products, while applying the same standard—why?
The driving factor for the development of a product basically is a need for that
product, being compliant to specific requirements and desired functions and proper-
ties. The specification of requirements is the first step towards a product. In a next
step, a component specification is derived from the requirements and the possibly
already-existing (partial) solutions, which then serves as the basis for all implemen-
tation processes. Requirements must be expressed in one way or another and from
there unique definitions and description of the functionalities and their implementa-
tions must be derived.
The difficulties when specifying the requirements, properties and functions
come from the limitation of resources in human imagination, human linguistic ca-
pabilities and description means. It is almost impossible to describe requirements
in an arbitrary way. Furthermore, none of the product designers is able to express
all of his or her ideas and describe them correspondingly in a formal language.
The number of designers for a specific product mostly is very limited. As such, it
is quite natural that these persons are not able to express the personal knowledge
completely or they even are not willing to do so. Specifications are textual docu-
ments in most cases. This is mostly due to the fact that purely formal languages are
not widely known or correspondingly needed tools are not available. Quite often,
it seems to be easier to describe certain mechanisms by words than to express them
in formulas and diagrams. On top of this, the application of a formal language such
as Specification and Description Language (SDL) or Unified Modelling Language
(UML) does not guarantee per se that such a description is understood in the same
way by everybody.
When mapping ideas into text and diagrams as well as into formal languages as
there are the system description languages and modelling languages, there is a gap
between the author's thoughts and the reader's comprehension. Any of the require-
ments descriptions and any of the specifications contain certain ambiguities which
may have more or less effect depending on the quality of the description and the
qualification of the reader. This consequently results in different implementations,
which should be avoided.
Currently standards are developed in cooperation with multiple companies. As
such, the quality of the specification documents under development is checked by
a consortium of persons. However, the implementation of the specified compo-
nent mostly is done by single companies only. The interpretation of a specification
of only a few persons consequently bares the risk that small deviations between
specification of a component and its implementation may occur. This effect shall
be called “interpretation deviation”. It can be observed too that when regarding the
definition of requirements and their specification, difficulties while implementing
