chapter 3 rigid pavement - DOT On-Line Publications - Department ...

ANALYSIS OF PERFORMANCE
The coring results and statistics are summarized in Table 4 fc
all six projects. A detailed listing of all dowel locations a 1
measurements is provided in Appendix A.
The types of analysis that were performed for each of the dowel
placement parameters included the following areas. A basic
analysis of averages and distribution densities was conducted
using means and standard deviations, and these statistics are
included in Table 4.
Additionally, analysis was performed on the direction of
deviation from the optimum dowel position (e.g. rotated left or
right, rotated up or down, longitudinally offset forward or
backward: with respect to the direction of paving). For all
dowel placement parameters on all.projects, the data had
approximately balanced normal distributions which were centered
at or near the optimum dowel position. The lack of skewed
distributions and lack of distributions centered well away from
the optimum position indicate that the variation is due to normal
random fluctuation of the two dowel placement methods. It
indicates that no pervasive systematic problems exist in either
of the dowel placement processes which would caused skewed data.
Analysis of directional deviation of the dowel placement
parameters versus the lateral position of the dowels across the
roadway was also conducted. Again, for all placement paramete
on all projects, the lateral position of the dowels across the
roadway had no significant effect on the placement parameters of
the dowels, indicating no pervasive systematic problems in either
of the dowel placement processes.
Vertical Translation: First, the distribution of dowel depths
was examined. The standard deviations for the inserter projects
(0.20" to 0.46") were comparable or smaller than those for the
basket projects (0.35" to 0.57"), indicating that the inserter is
capable of consistent depth placement of the dowels. This does
not necessarily mean that the inserter is better in this respect
than baskets, because the frame of reference is different for the
two placement methods. The depth of the dowels was measured from
the pavement surface down to the top of the dowels. Dowel
baskets are staked to the base course, thus referenced to the
bottom of the slab. As the thickness of the pavement varies
along the length of the project (typically 1" or more
fluctuation), the depth of the dowels, as measured from the
surface, would vary directly with the fluctuation of the slab
thickness. The placement of dowels by the inserter is referenced
to the paver frame, and is thus more closely correlated with the
pavement surface. Thus, fluctuation in pavement thickness should
have little or no effect on dowel depths for the inserter
projects. In conclusion, the dowel bar inserter is capable of
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