Pavement Management

One of the tools Public Works uses to maintain the county road system is pavement management.  With over 380 miles of travel lane, the majority being paved or chip sealed, maintaining a safe, durable road surface takes significant advanced planning and substantial resources.  The department's pavement program includes the use of professional consultants, GIS functions, and database programs to track overall pavement conditions and establish annual pavement treatment schedules.

In 2018, the department restructured its pavement program and began treating (paving or chip sealing) roads based on a 12-year treatment cycle.  Prior to 2018, each season's treatment list was compiled based primarily on road conditions and those in the worst condition or with the highest traffic volumes were generally considered the priority.  With the program restructuring, county roads are now grouped by location and will received some form of pavement treatment every 12 years.  Based on the pavement condition of a specific road, during its cycle it may be recommended for a single chip seal, a thin-mix asphalt overlay, or some other variation of treatment.  The change in approach has shown to reduce costs and to be a more effective use of time, labor, equipment and other resources.

The information provided below is a general overview of basic pavement treatment methods.  For information about what roads are programmed to be treated in the future, please review the 2023-2024 Public Works Paving and Chip Seal Plan.  Prep-work for 2023 roads will begin in late-April and early-May, with paving and chip seal work tentatively scheduled to begin in early July.




What is Chip Seal?

A chip seal is when an emulsified asphalt is sprayed onto the road, followed by a layer of crushed rock, creating a chip "seal".  Depending on the program, a second layer of asphalt and rock may be applied, therein creating a "double shot" chip seal.  The application is usually compacted with a rubber-tire roller to ensure the rock fully adheres to the asphalt   Some loose gravel may remain on the road for several days while the asphalt hardens, so lower speed limits are often imposed during this time.  Ensuring vehicles drive slower on the new surface will minimize rutting and potential destruction of the chip seal, as well as minimize loose gravel from being thrown from tires.  Please remember that fines for speeding may be doubled inside construction zones.

Depending on what resources are available, any loose gravel will be swept up anywhere from 1 day to 2 weeks after the chip seal is applied.  In many cases, a diluted emulsified asphalt mixture (50% water) will then be applied to further seal the new road surface.  This final application is commonly referred to as a fog seal, which provides an additional surface seal to retain rock and repel water.  The fog seal also provides a good contrast between pavement markings, which can usually be applied within 24 hours of the fog seal.

Advantages to Chip Sealing
  • A new seal can minimize water saturation and extend the lifespan of the road surface.
  • Vehicles can generally drive on chip seals within a few hours after being applied.
  • Chip seals are a proactive and cost-efficient preservation process used nationwide.

Other Forms of Pavement Maintenance

  • Crack seal is a rubber seal applied over existing cracks in the pavement to prevent moisture from getting in and increasing the size of the pavement opening. This is an inexpensive treatment, and typically performed on roads a year before they receive a chip seal or asphalt overlay. 
  • Slurry Seal is the application of a mixture of water, asphalt emulsion, small rock aggregate, and additives to an existing asphalt pavement surface. The placement of this “slurry” mixture on existing pavement is intended to seal the pavement surface and prevent water from infiltrating the substructure and causing permanent damage to the road. Slurry seals are applied in order to help preserve and protect the underlying pavement structure and provide a new driving surface. Roads chosen for slurry seal applications generally have low to moderate distress and narrow crack widths. The asphalt emulsion and aggregates are mixed in a truck that distributes the slurry over the pavement. Workers with squeegees follow behind and assist in spreading the mixture.
  • Asphalt overlay is a replacement of the top layer of the road. The thickness of the overlay can vary, however most treatments are typically 1.5” to 2” thick, also referred to as a "thin-mix overlay".  An overlay improves the smoothness of the road, adds to its structural strength, and if applied at the appropriate time can extend the lifespan of the road by may years.  The process of overlaying starts with sealing cracks and removing damaged areas of asphalt, usually within the wheel paths.  This work is often done up to one year in advance to allow for adequate curing time.  Once the overlay is applied and compacted, the surface temperature is monitored until it is safe to allow traffic to resume travelling on it.  Since an overlay doesn't require any additional curing time, traffic delays are usually minor and in short durations.
  • Full reconstruction is digging out the existing road completely and laying new sections of base rock and asphalt. This is a high-end process for roads that are beyond any life-extension treatment and usually the most expensive option.  Generally speaking, most other forms of pavement treatment are performed in order to prevent a full reconstruction from being necessary.