required to deal not only with the structural requirements of the slab but
also to counteract reflection cracking resulting from movements in the joints
within the underlying concrete slab (HD 32/94) (DoT, 1994d).9.3 Compiling information on the pavement’s condition,
An inventory of highway condition data is updated on a routinely regular basis
in order to determine the condition of the pavement and whether its level of
deterioration is such that remedial action is necessary. The data compiled will
allow trends in the structural condition of a pavement to be established.
The four major types of routine assessment are (HD 30/99) (DoT, 1999):
Visual condition surveys
High speed road monitor
Deflectograph
SCRIM (see section 9.7).
The first three are dealt with here, and the fourth later in the chapter.
Visual condition surveys
These record defects that remain undetected by machine-based methods. As the
method is slow and laborious, it is usually targeted on specific areas in particu-
larly poor condition. The surveys provide factual information for deciding on
the most appropriate structural treatments, and identify sections of highway
suitable for remedial treatment. Planning for long-term treatment can thus be
undertaken, with performance of the pavements being monitored and priorities
for treatment being established on the basis of the database compiled.
In past times a Marshall Survey represented the usual method for preparing
an inventory of the condition of sections of highway. It involved groups of tech-
nical staff compiling information throughout their area on the condition of
carriageways, kerbs, etc. Nowadays, the information can be collated using the
computer program CHART (Computerised Highway Assessment of Ratings
and Treatments), a management system for assisting maintenance engineers. It
provides information on the lengths of highway that are substandard, the treat-
ments required and the relative priorities for treatment.
For every 100-metre section of highway, CHART convert defects information
into numerical ratings for each existing defect. Those defects requiring treatment
can then be identified. The ratings, which are subjectively based, indicate the
relative urgency of the need for treatment.
Typical output is:
Map CHART – the quantity of defects are shown by chainage both along and
across the highway
Pavement Maintenance 253