Road & Drainage Improvement Projects
The Engineering Division manages a variety of projects in it's long term Capital
Improvement Program (CIP).
County Roads are resurfaced annually as part of the Prescription for Progress road
improvement program. The resurfacing projects include dirt and gravel road paving,
pavement recycling, full-depth patching, surface treatment, chip seal, and conventional
asphalt overlay. The 2001-2002 resurfacing contract pioneered the use of
rubberized asphalt overlay on selected roads. Roads are selected for resurfacing based on
pavement condition evaluations by geotechnical consultants. Roads with the lowest Overall Condition
Index (OCI) are added to the paving list. The type of resurfacing option(s) to be used
on selected roads is determined after further investigation of the existing pavement
thickness, subgrade condition, traffic use, and other factors.
A number of methods and processes are used for resurfacing County roads.
Listed below are descriptions of some of the methods and processes.
Pavement recycling in its simplest form involves milling the existing asphalt,
mixing the milled asphalt with a binding agent, and compacting the mixture
by rolling. A significant advantage of the process is that it saves on raw
material costs. The process is well-suited for thin or average depth asphalt
roads with extensive alligator cracking, which are not suitable for full-depth
patching. There are two methods; Cold Process recycling and Hot In-Place recycling.
The cold process recycling method uses cold binding agents or emulsions; this
method usually requires a couple of weeks after milling and compacting for the
road to set up. The hot in-place recycling method employs an extensive system of
heaters, milling heads, spray bars and screeds which remove and replace up to 2"
of asphalt surface in a continuous process. At the present time, the County only
uses cold-process recycling.
Full Depth Patching
Full-depth patching refers to saw cutting and replacing segments of the existing
pavement to its full depth, as opposed to an overlay which only replaces the top
portion of the pavement. One of the most important steps in the patching process
is to provide a weatherproof seam. This is done by saw cutting a clean edge and
applying liberal amounts of asphalt tack to the face of the joint or laying a
geotextile fabac before paving. Full-depth patching is done on roads that are in
relatively good shape except for isolated areas which need patching.
Surface Treatment refers to the application of a geotextile fabric to increase
the shear strength of the overlaid surface. The fabric helps to reduce a condition
known as reflective cracking in thin asphalt overlays. It is commonly used for roads
which are to receive a thin asphalt overlay but which have widespread, moderate
cracking (not severe enough to warrant recycling). The process begins with a binding
agent being applied to the road to anchor the geotextile fabric. After the fabric is
laid and the binding agent is set, (This takes approximately 24 hours), the road
receives a surface coat of 1-1/2" to 2" of asphalt.
Chip seal is sometimes employed as a maintenance measure to prolong the service
life of a roadway or to enhance vehicle traction. However, it is not intended as
a replacement for more effective and long-lasting repair methods since the process
does nothing to improve the structural qualities of the roadway. The first step in
the chip seal process is the application of hot liquid or cold emulsion binding
agent to the roadway surface. A thin layer of crushed stone is then applied to the
binder. Traffic over the stone layer helps to anchor the stone, although motorists
usually complain during the first week or so about excess stone coming off the road
as they drive on it.
Rubberized Asphalt Overlay
Rubberized asphalt technology holds promise for enhancing the structural qualities
of asphalt while also providing a way to recycle tons of discarded tires. In its
upcoming 2002 paving program, the County will be using a new process administered
through the Asphalt Rubber Technology Service (ARTS) by Clemson University to produce
and install a 2" thick rubberized asphalt overlay on approximately 4 miles of roadways.