| dc.description.abstract | The good visibility of traffic signs is of essential importance so that drivers can perceive them and
carry out the most appropriate actions for the safety of themselves and other drivers. However, it
is sometimes possible to observe signs that, during the day, are visible and look good, but that, at
night, their colors do not transmit the same information. One of the existing methods for estimating
the ability of the retroreflective sheeting to be viewed at night is the retroreflective readings
performed with portable measuring devices. This research aims to measure and analyze the results
of retroreflectivity of sheetings used in traffic signs implemented in the experimental segment
located in the city of Santa Maria/RS, in addition to evaluating, in the laboratory, the behavior of
these retroreflective sheeting. The experimental segment has 24 signs in four different colors and
three types of retroreflective sheeting, according to the NBR 14644 (2013) standard. A sign of the
same color and of the same type was duplicated to observe the effect of dirt over time, since one
was cleaned with water and neutral soap and the other was not. In the comparison between colors,
types of sheeting and cleaning, it was found that, in relation to the loss of retroreflectance, only
cleaning proved to be a statistically significant factor in the 75 months (6.27 years) of analysis.
Based on the predictive models generated in this study for the sheeting exposed in the
experimental segment, the set of sheetings without cleaning showed, on average, a loss of retroreflectance in relation to the initial measurement about 7 times greater than the set of sheetings
that received regular cleaning . Regarding the correlation between the retroreflective performance
of sheetings tested in an accelerated artificial aging equipment (Suntest XLS +) and field
measurements, there was no exact correlation between the behavior of the two tests, since there
was a distinct behavior between the measurements obtained field and those tested on the Suntest
XLS +, for a 1.5-year boundary condition of accumulated radiation (300-800nm). However, in
comparison, the correlation between the retroreflective measures and the accumulated radiation
exposed sheetings in the Suntes XLS + showed a greater correlation between these two variables
than in the field. It was observed that meteorological phenomena, such as rainfall, were not shown
to be significant factors in the cleaning of the retroreflective sheetings and, consequently, neither
in the increase of the measured values of retroreflective. The temperature of the sheeting was
shown to be influential on the retroreflectivity. Evaluating the sheetings exposed in the monitored
segment during a day, it was verified, for a variation of 25ºC in the temperature of the sheeting, that
there was a change of 20% in the retroreflectivity of the types I and X and of 40% for the type III.
Comparing the predictive models found in the literature with those generated in the experimental
segment, it was not noticed a percentage of annual loss in relation to the initial retrorefletivity,
however the highest percentage of the models (75%) presented an annual loss between 0% and
5% in relation to your initial measurement. In addition, the time during which the models presented
retrorefletivity below the minimum Brazilian and North American parameters was analyzed. For
Brazilian requirements, the highest frequency of failure was between 0 to 15 years of service; for
the North American, it was 5 to 20 years of activity. Sheetings of types III and X were conditioned
in a humid chamber, with the objective of evaluating their behavior in an environment with a high
percentage of humidity. With that, it was found that the sheetings obtain, on average, an annual
loss in terms of the initial retroreflectivity of 11% over the initial retroreflectivity. | |
