# Long-Term Monitored Road Degradation Functions as a Tool to Increase Quality of Pavement Design
## 4 Discussion and Conclusions  
This paper presents the results associated with the creation of degradation functions of the 1 st class road in Slovakia in the section between the villages Porubka and Poluvsie. Approaches of non-destructive data collection for a period of 20 years were used in the work, in combination with mathematical modeling and application of the results of sensitivity analysis using a simple Pearson's coefficient. The result is the creation of highly sought-after road degradation functions. These are expressed by polynomial functions of at least the third degree, as they best express the dependences between the traffic load and the development of longitudinal and transverse inequalities. At the same time, the measurements confirm the conjecture that the right wheel path (within one direction) deforms faster. On the measured section of the road, the difference between the values of deformations in places was up to 38% more. This is mainly due to the insufficient width of the road, despite its importance. The vehicles are forced to drive close to the curb, which creates a higher surface tension in the right part of the road in the right wheel path. This also causes earlier damage to the curb and subsequent cracks due to water seepage into the lower layers of the road. The study also verified the assumptions associated with the effect of temperature and traffic load on the values of rut, IRI and road load capacity. The biggest impact is on the top layer of the road. Mathematical performance models have not yet been validated in detail with degradation models by other researchers. However, the author team initiated several new activities with its partners, which could unify the boundary conditions for data collection. This would ensure that there are not too many gaps when comparing the same road design. Subsequent work will have the character of application of the identified degradation functions to other long-term monitored sections of roads with the same design properties to bring verification of mathematical modeling. Among the new ideas that emerged during the study, it is possible to include the continuation of measurements, but under improved technical conditions. This means that the tests are carried out in such a way that climatic similarity is observed, measurements at different seasons and, in particular, measurements at the same places on the road. At the same time, it is appropriate to focus on the application of new technological tools in the form of sensors that could simplify and improve the entire data collection process. Conceptualization, L.M., S.S. and J.S. ; funding acquisition, S.S. and P.D. ; resources, L.M. and M.K. ; validation, L.M. and J.S. ; investigation, L.M., S.S. and L.R. ; methodology, S.S., P.D. and L.R. ; writing--original draft preparation, S.S., L.M., J.S., L.R., P.D. and M.K. ; writing--review and editing, L.M., S.S. and L.R. All authors have read and agreed to the published version of the manuscript. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Road Foundation** & **Subsoil** & \multicolumn{4}{c}{**Asphal-Bonded Construction Layers ***} \\ \cline{3-6}  & & & **20.01–30.00 \({}^{\circ}\)C** & **10.01–20.00 \({}^{\circ}\)C** & **5.01–10.00 \({}^{\circ}\)C** \\ \hline Rut (left) & r = \(-\)0.73 & r = \(-\)0.31 & r = \(-\)0.77 & r = \(-\)0.43 & r = \(-\)0.73 \\ \hline Rut (right) & r = \(-\)0.54 & r = \(-\)0.38 & r = \(-\)0.88 & r = \(-\)0.58 & r = \(-\)0.22 \\ \hline IRI & r = \(-\)0.70 & r = \(-\)0.21 & r = \(-\)0.73 & r = \(-\)0.70 & r = \(-\)0.70 \\ \hline \hline \end{tabular}  
* Divided by surface temperature during measurement.  
\end{table} 
Table 3: Overview of Pearson coefficient for the road construction layers. **Funding:** This paper was supported under the project of Operational Programme Integrated Infrastructure: Research and development of contactless methods for obtaining geospatial data for forest monitoring to improve forest management and enhance forest protection, ITMS code 313011V465.