Environmental Engineering Reference
In-Depth Information
examples of the assignment of condition to PFs.
There are likely to be instances where on-site
findings do not match exactly with the flowcharts
or tables as it is impossible to cover every possible
permutation of condition that could occur in prac-
tice. Inspectors must use their judgment and ef-
fectively use the confidence assessment where
the assessment of a PF is ambiguous.
recording of a large amount of data therefore in-
creasing the duration of the inspection process. It
also requires that the checklists used are fairly
extensive and detailed in their content. There is a
danger that any findings from the inspection that
do not fit into the checklist may be ignored.
The guidance method chosen for use in the
condition indexing process was primarily flow-
chart based. This was felt to provide the structure
needed to ensure consistency of inspection and, in
addition is a simple-to-use method that does not
require too much additional input from the in-
spector, unlike checklists.
Flowcharts were designed using some general
principles. They start with a process box at the top
of the chart describing the performance feature
being assessed (and the failure mode it applies to
where relevant). The five condition grades are
listed along the bottom of the chart going from 1
to 5 from left to right. All flowchart decision boxes
are answerable with a 'yes/no' or 'none/minor/
severe' type response where possible. In those
instances where this is not possible, the potential
responses are explained where they are applied or
within the notes attached to a chart.
The definitions of 'minor' and 'severe' referred
to commonly in the charts refer to the following
general descriptions:
.
Minor
- the itembeing assessed is only visible to
detailed inspection of the performance feature. For
example, a minor misalignment of the crest of a
vertical wall would only be visible if the inspector
were to closely examine the crest looking along it
and comparing it with other wall sections.
.
Severe
- the item being assessed would be easily
visible under a cursory inspection.
Using the previous example for the crest of a
vertical wall, a severe misalignment would be
obvious to the inspector as he or she approached
the asset. It would not require close inspection to
identify, and would be visible to a non-expert or
member of the public.
To reduce ambiguity, notes have been attached
to those charts where it was felt that the decisions
to be made could be unclear. As a final point
regarding guidance, it must be noted that guidance
is only intended to
guide
the inspector and give
The Condition Indexing Process
A number of activities form the condition index-
ing process, and thesewill nowbe described to give
a better understanding of the overall process being
proposed.
Pre-inspection: data gathering and planning
Prior to the actual inspection, an inspector should
obtain all the relevant data relating to the sites to
be inspected. This could include previous asset
inspection records, local geography and asset loca-
tions, design records, local geotechnical informa-
tion, asset topography and the standards of
protection afforded by the assets (i.e. their perfor-
mance specification). The exact data requirements
will also be determined partially by experience and
knowledge of the assets to be inspected. Previous
inspection data should always be examined to
provide a comparison with the inspection to be
carried out, to observe any changes to the asset
occurring over time, and to highlight any known
points of weakness for more detailed inspection.
Assessment of the performance features
This step of the process represents the actual on-
site inspection of the asset. The inspector performs
a detailed observation of the asset and assigns
condition and the associated confidence scores to
each PF in turn. The method for achieving this is
left to the inspector's discretion. For the set of PFs
relating specifically to a single failuremode (visible
deformations of cross-section or obvious structural
deformations), the inspector must be careful to
establish the specific PF or PFs occurring as there
