Abstract

Introduction and background

Materials and methods

Methods

Results

Service life extensions

Conclusions

Acknowledgements

Funding

References

Abstract

     With increasing economic pressures worldwide, the amount of money spent on pavement preservation needs to become more effectively utilised. Historically, the Long-Term Pavement Performance (LTPP) study has led to data-driven performance expectations for treatments. Pavement management systems (PMS) allowed many to form analytical methods to evaluate pavement performance, from trend fitting to benefit analysis. Taking these methods and applying them to the Iowa Department of Transportation’s (DOT) pavement management information system (PMIS) database can determine preservation utility as well as provide expectations of pavement treatments. Thirteen slurry seal projects across the wet/freeze climate of Iowa, U.S.A., were analysed to determine the service life extensions and yearly benefit for their pavement condition, rutting, riding, and cracking indices. This study aims to provide a framework for future analysis of more preservation treatments and other PMS databases. Understanding local performance of various preservation methods leads to better pavement management and economically sound decisions.

Introduction and background

     With increasing economic pressures worldwide, the amount of money spent on pavement preservation needs to become more effective and appropriately utilised. To properly allocate spending on pavement preservation, two general approaches utilising a pavement management system (PMS) can be used. The first approach involves prioritising various roads within a network, typically based on the roadway type (arterial, collector, residential, etc), current pavement condition, annual average daily traffic (AADT), and other factors important to the involved agency. However, the second approach involves the understanding of preservation performance based on actual treatments applied with local means and materials. Analysing past performance data and identifying trends provides the ability to better quantify the effectiveness of preservation treatments.

     The objective of this study is to evaluate the performance of slurry sealing on Iowa roadways, a wet/freeze climate, to better understand their effectiveness as a pavement preservation treatment. Four pavement performance indices are evaluated and compared using reflected, logistic, sigmoidal (RLS) curves.

Results

     All projects were analysed, and a best fit function was fitted to the data using an RLS function to develop a pavement performance curve, the index benefit throughout each relative year, and the service life extensions for PCI and the rutting, riding, and cracking indices was evaluated for the thirteen slurry seal projects. Each ‘Do Nothing’ and ‘Observed Performance’ trends for all four indices of all thirteen projects were measured and life extensions were evaluated. Statistical data from such small sample sets only provide limited results; however, observed trends over multiple projects help to develop performance expected trends as performance of more treatments becomes available.