Anyone who has spent time on a limestone road knows the drawbacks of that particular road surface. When it is dry the dust from a limestone road covers cars and trees on the sides of the road. If you are outside as a car drives by it can be difficult to breath because of the dust. If it is rainy the road develops lots of pits as softer areas of limestone turn into potholes.
The potholes require public works to re-grade the limestone to fill in the holes and possibly for new limestone to have to be added. This maintenance is expensive and the county is using millings to surface limestone roads.
When a paved road is resurfaced the asphalt is grinded to create a level surface or just to recycle the road. The asphalt is grinded and that created millings. These millings are ground up pieces of asphalt.
According to the county "The program calls for using a recycled asphalt product as an alternative to limerock road. For this program, millings are only considered and applied to rural limerock roads with traffic volumes <250 vpd (vehicles per day), relatively straight roads with minimum driveways and cross streets. In reality, millings are a temporary solution to several issues associated with limerock and the use of millings is not the long-term solution for unpaved roadways."
"A 5-Year, 3 Zone plan was presented and approved by the Board in October 2015. The total estimated maintenance savings for this program for roads milled to date is $110,880. It is anticipated that an asphalt milling surface will reduce road maintenance expenditures on an average of $2,800 per mile/per year."
In addition to the savings the milling covered road makes a smooth surface and reduces the dust. The millings covered roads are an improvement over the limestone.