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Jesse Berg knows every mill-and-overlay project is different. But the project on 16th Street SW and 37th Avenue SW is on a whole new level.
“If you’ve driven 16th Street SW and 37th Avenue SW prior to this project, you know exactly how it’s been,” Berg said. “So we have quite a few steps in this process. We’ve completed the concrete work. We’ve done patching of the most severe cracks, and now we’re milling.”
Berg, a project engineer with the City’s Engineering Department, said his department collected more than half a million data points on these sections of 16th St SW and 37th Avenue SW to essentially create a digital rendering of the roadway. That data was used to design the repairs that are under way.
“Based on those data points, we’ve created a surface so we know exactly how much to mill in each location,” he said. “We call this a profile mill because we’re re-establishing the profile of the road to get a good slope from the center of the road down to the curb.”
In a typical mill-and-overlay project, a consistent amount of asphalt is removed from the roadway; for example, 4 inches of asphalt might be removed from the road being repaired, then any necessary repairs are made before the roadway is leveled and a new layer of asphalt is put down to create the driving surface.
The project on 16th Street SW is a bit more complicated and nuanced than that, with crews doing the profile mill.
This milling process includes some areas where a few inches of asphalt are being removed, but on other areas of the roadway, no asphalt is being removed. In fact, in some spots, as much as four or five inches of new asphalt will be added to rebuild the road’s crown in addition to the asphalt needed to replace what has been milled.
Berg said some sections of 16th Street SW in the construction zone are nearly level, which means water doesn’t drain properly. Rebuilding the crown of the deteriorating road will ensure proper drainage, which will help the surface last longer.
After the milling process is complete, asphalt fabric will be used in some locations to help repair some of the major cracks, reducing the chance the cracks will come back.
“Once we’re done installing that fabric, we’ll actually come back and add pavement to the center of the road to establish the grade that we want prior to repaving the entire surface,” Berg added. “The goal of this profile mill, blade leveling, and paving is to provide the smoothest surface possible.”