Highlighter Fall 2015

2 | Pond NOT SO SIMPLE RESURFACING IN FLORIDA! The Resurfacing, Restoration, and Rehabilitation (RRR) program in Florida is anything but simple E very year I go to my daughter’s school for the Great American Teach-In, and I explain that engineers Design, Build, Operate, and Maintain just about everything we use in our everyday lives. Then they get to “design” and “build” a marshmallow tower. They “operate”, or play, with it and it starts falling apart. Then it is time to “maintain” it… and that is where I lose them. Most people think of maintenance on anything the same way my teenager feels about cleaning her room; it is a dreaded chore. In terms of highway maintenance, we maintain asphalt pavement through milling/resurfacing and concrete pavement through sealing cracks and replacing slabs. These activities by themselves seem fairly simple and routine, like a chore. However, the Resurfacing, Restoration, and Rehabilitation (RRR) program in Florida is anything but simple. Since asphalt was first used in the United States in the 1860’s, there has been a need to maintain and prolong its life. Most state Departments of Transportation (DOTs) have a resurfacing program. In the Federal Highway Administration document, Good Practices: Incorporating Safety into Resurfacing and Restoration projects (dated December 2006), discusses how roadway maintenance programs and safety programs are merging and provides guidance on how to do this. The RRR process in FL starts with “extending the service life” of the pavement and even this can get complicated. Most asphalt pavements are designed for a 15 to 20 year service life and concrete pavement can last up to 30 years. But this expectancy is only if the traffic projections and equivalent single axle loads (ESALs) over the design service life match actual conditions. While more often than not, our estimates and calculations are correct, there are always those special cases when something outside our control or an unknown factor cause the service life to be significantly lower than anticipated. Let me give you just a few examples of projects I have worked on. On SR 44 in Lake County from the County Line to SR 44.CR 468 , the existing pavement was failing and severely rutted. After obtaining traffic data and looking at the current and projected ESAL values, it was determined that the existing asphalt pavement section was structurally deficient or simply not thick enough to handle increased truck traffic on the corridor. Two options to rehabilitate the roadway were reviewed, reconstruction of the entire roadway or add additional structural course to the existing pavement section and raise the profile of the road. Ultimately, adding the additional structural course was the more feasible option. Sounds simple, right? Wrong. In order to provide the required structural number for the projected ESAL data, an additional two and a half (2.5) inches of Super Pave (SP) structural course was added to the roadway. This required all the median openings to be raised and reconstructed, all of the shoulders had to be reconstructed with front slope revisions, and all the driveways had to be re-profiled. On SR 674 in Hillsborough County , there was settlement or a depression in the roadway just east of the Carlton Branch Bridge that was causing trucks to “bottom out” and scrape the existing asphalt. Several patches or overlays were attempted in this area, but the depression continued to form over time. When it came time for the regular resurfacing of this corridor, additional core data that went deeper than typical cores was obtained. This additional core data revealed that there was an isolated pocket of clayey soil about 5 feet below the base material. Due to the heavy truck traffic on this corridor, the clayey soil were continually compressed. The simple repair would be to just dig down and remove the clayey soil, right. Unfortunately, this project was on a two lane rural roadway, with the only detour option being almost 10 miles long. The solution chosen was to strength “...it was determined that the existing asphalt pavement section was structurally deficient or simply not thick enough to handle increased truck traffic on the corridor.”