Hot Mix Asphalt (HMA) overlay is a commonly used rehabilitation treatment on the arterial road system in Mason County. Counties are required by law to use a Pavement Management System to guide their annual pavement preservation activities, which includes "rating" the county arterial road system every two years for defects.

The pavement rating score, daily car and truck counts (ADT's), along with existing base and pavement structure information are all factors when deciding what type of preservation treatments should be used, and when they should be made.

Generally speaking, an overlay is viewed as a more appropriate treatment on heavily used roads. Where Chipseal applications only seal a road to moisture and adds a new traction surface, an overlay adds structural strength to support the heavy traffic use. Since 2004 Mason County has been applying Chipseal treatments on arterial roads to extend the interval between overlays. This combination of treatments will ultimately lower the life cycle costs for those road segments.

Who Does the Work?

Costs are variable depending on the depth of overlay, road width, number of intersections and accesses, and shoulder widths. An average cost for an overlay is about $250,000 per mile. Our cost for a Chipseal application, which is done by county employees, is about $32,000 per mile.

One has to keep in mind how the escalating cost of a barrel of oil has impacted road preservation over the last decade. It is now about three times more expensive to purchase materials associated with Chipseals and overlays.