Asphalt Maintenance
The Pavement Management Program is an Information Management
System, which allows the City to track the history, surface condition and
distresses of every street in Mesa. Pavement condition surveys are performed
each year on over 1,200 miles of streets. Information from the annual
surveys identifies specific areas where various types of preventive
maintenance treatment, such as slurry seal, acrylic seal or other sealcoats,
can be applied. The surveys also identify areas requiring more aggressive
rehabilitation projects like a rubberized asphalt overlay or partial
reconstruction.
Each year over 6,000,000 square yards of needed work is
identified, prioritized and delegated. One goal is to establish
a balanced treatment forecast plan for the street repair and
preventive maintenance program that will help to maintain
targeted pavement condition levels. These levels are based on a
Pavement Condition Index (PCI) of 0 to 100, with 100 being
excellent and 0 being failed. The PCI is calculated from data
collected during the annual pavement condition survey. The City
has been collecting pavement condition, inventory and
maintenance history information on Mesa streets for over 18
years with details and quality of data improving with each year.
The City also manages sidewalk repairs to ensure they are
safe for pedestrians and help prevent injuries cased by damaged
sidewalks.
Pavement Maintenance Programs
A variety of programs are used to help keep our streets in
the best possible condition and extend their service life. Below
are definitions of commonly used pavement maintenance
techniques.
Pothole Repair
When a small isolated section of roadway fails, we call it a
"pothole." Typically water has seeped under the pavement
surface, creating pockets of water that fracture the surface
when traffic compresses the water underneath. These potholes
are temporarily repaired with a cold-mix asphalt. If a section
of roadway has numerous failures because the sub-base under the
road surface is compromised, permanent repair may be delayed
until a better solution can be funded and implemented.
Asphalt Patch
When a roadway is generally in good condition but there are
isolated sections that show signs of failure, asphalt patching
is performed to improve the overall condition of the street. We
currently utilize two practices for patching asphalt:
Mill & Cap - Sections of the roadway that show signs of
failure are milled down to the good pavement base. The milled
down areas are then capped with new hot-mix asphalt.
Remove & Replace - Sections of the roadway that show signs of
failure are saw-cut and the asphalt is completely removed. The
sub-base is compacted and the section is paved with new hot-mix
asphalt.
Crack Seal
Asphalt pavement is designed to be flexible. This allows it
to adapt to the wide temperature swings we have in Arizona. The
flexing causes cracks to develop in even relatively new pavement
and this will continue throughout the usable life of the roadway
surface. To limit deterioration, cracks are filled with a
rubberized sealant we call a "Crack Seal" that will
restrict
water penetration and fill voids in the surface.
Sealcoats
There are two main types of surface treatments applied to
extend the life of the pavement: Fog Seal and Slurry Seal.
A fog seal is a thin layer of asphalt emulsion applied to the
streets surface to prevent oxidation, loss of fine aggregate and
add asphalt material to the surface course. Depending on traffic
speeds and street conditions there are three types of emulsions
that may be applied as Fog Seal. Tire Rubber Modified Surface
Seal and Plastic Seal both use additives to increase the life of
the product and are used on residential and low volume streets.
Cationic Quick Set Emulsion has no additive and is used on
arterial and high volume streets.
A slurry seal is a 3/8" to 5/8" mat of asphalt emulsion,
water and aggregate applied to the street to create a new
wearing surface. This application is generally used to extend
the life of the existing pavement on streets that show signs of
surface deterioration.
When your street is scheduled to be treated, pre-warning
signs will be placed at various entrances/streets into the
neighborhood approximately two weeks in advance. Residents will
receive a door hanger with instructions two to four days prior
to their street being closed for seal coating.
Mill and Overlay
If large areas of a roadway are showing signs of structural
failure, potholes or alligator cracking, the section can be
milled down to the good pavement base. This is followed by a
new hot-mix asphalt overlay, extending the life cycle of the
original pavement.
Reconstruction
When a roadway has reached the end of its life cycle and can
no longer be rehabilitated, a new road must be constructed. All
existing pavement will be removed and can be recycled for use as a new
sub-base. The old sub-base will be regraded and compacted and a
new hot-mix asphalt surface applied.
Service Cuts
The most common work seen on the road has nothing to do with
pavement maintenance. These are areas where utility crews are
cutting into the road surface, digging down below the surface to
add or repair sewer, gas, or water lines. During the course of
construction they will cover these areas overnight with metal
plates or a cold-mix asphalt. When completed, the area will
be re-compacted, a new sub-base installed and a hot-mix asphalt
applied.
Transportation
300 E. 6th St.
Mesa, AZ 85201
Mailing Address:
City of Mesa
PO Box 1466
Mesa, AZ 85211
Office Hours:
Monday - Thursday
7:00 a.m. - 6:00 p.m.
Closed Fridays & Holidays
480.644.2160
480.644.2262 (after hours)
E-mail
MyMesa