Pavement-management systems (PMS) place an emphasis on concrete-pavement preservation (CCP) efforts, aiding governing bodies in staving off the need for extensive—and expensive—reconstruction, while maintaining a high standard of quality within the road network. Several techniques are part of the CPP toolbox:
- Slab stabilization
- Full-depth repair
- Partial-depth repair
- Dowel bar retrofit
- Cross-stitching longitudinal cracks/joints
- Diamond grinding
- Joint and crack resealing
States began to implement PMS more than 30 years ago, and today there are identifiable methods of assecessing a road network’s needs and budgeting resources accordingly. However, these methods are not uniformly used or understood across the United States. Kentucky serves as an example of one state that has continued to explore best practices management of CPP. The Kentucky Transportation Cabinet has made strides in determining data that can serve as a model for other DOTs looking to accomplish a wider deployment of PMS.
Diamond grinding is the most common CPP technique used in Kentucky. The state has been performing diamond grinding since the mid-1990’s, but “at that time we were really just exploring our options—not a lot of diamond grinding was being done,” said Jon Wilcoxson, Division Maintenance Director-Kentucky Transportation Cabinet.
That changed in 2007, when the state increased its pavement-preservation activities in an effort to improve the roadway system. From 2007 to 2012, 862.6 interstate lane-km (536 interstate lane-miles) were diamond ground statewide, primarily in Louisville, Kentucky. Due to the diamond grinding during this period, International Roughness Index (IRI) measurements for Kentucky’s interstate concrete pavements greatly improved from an average of 112.1 in./mile to an average of 74.5 in./mile—the longest sustained improvement in the state’s IRI and its lowest recorded average IRI ever. CPP saved the state reconstruction costs of more than $1 Billion. The life-extension for the pavement is 10-15 years.
“We’re getting this at the top of the curve, and delivering a much improved product for the driving public.” said Wilcoxson.
Which one to pick? When assessing its road network for needed repairs, the main indicator employed in Kentucky is pavement smoothness. Inertial profilometers are used to annually measure roughness on the interstate system, and IRI values greater than 120 inches per mile will generally trigger CPP—a number used as a guideline. Undertaking CPP is contingent upon a situation in which there is moderate to low cracking and faulting. Pavements lower than 130 could still trigger CPP is it appears that cracking and faulting will become a major problem, but if a road is expected to require major work (i.e., widening) within 5-10 years, the cabinet will not recommend CPP.
Groups Kentucky is currently developing a process whereby the central office pavement management staff will work with district personnel to evaluate and provide direction for the entire pavement preservation program. The group will be responsible for:
- Reviewing the project selection process
- Updating the project selection process
- Ensuring proper training of inspection staff
- Writing specifications
- Evaluating potential new treatments
Wilcoxson stated that the more comprehensive process can improve alignment among participants. Kentucky is modeling its changes on similar systems in other parts of the Midwest—particularly on practices shared at a meeting of the Midwestern Pavement Preservation Partnership (MPPP-an American Association of State Highway & Transportation Officials (AASHTO) regional forum on CPP) by MnDOT—a leader in CPP.
Furthermore, Kentucky is adopting a laser crack management system (LCMS) for distress data collection and the development of automated predictive models for use in PMS. Kentucky, having successfully balanced lessons learned from other states with the independent development of CPP solutions that fit its individual requirements, is realizing the benefits and savings resulting from the use of an effective pavement management system.
For the Preservation Profiler and more detailed information, please download the PDF article by contributing author Kristin Dispenza titled “Quite a Stretch of Road…Kentucky Prolongs Life of Concrete Pavements”, please click here.
For an International Grooving and Grinding (IGGA) article titled “Kentucky Uses Pavement Management Systems to Reduce Costs and Improve Pavement Smoothness”, please click here.
For an IGGA ‘Concrete Pavement Surface Restoration’ article titled “Comparison Between Diamond Grinding vs. Carbide Milling for Surface Restoration”, with further information on diamond grinding, please click here.
