Improving NC Infrastructure through Bridge Inspections
1. C
minus. That is the embarrassing grade awarded to North Carolina’s
infrastructure by ASCE in its 2013 Report Card for the deteriorating
condition of existing structures. In response, Alpha & Omega Group
(A&O), a civil, structural and water resources engineering firm in Raleigh, sees
its increasingly important role in North Carolina Department of Transportation
bridge inspections as a way to help improve state infrastructure. Since 1998,
A&O has provided over 1,400 National Bridge Inspection Standards (NBIS)
bridge inspections to the NCDOT throughout the state. Since the Report Card
was made public, however, the firm has stepped up the number of inspections.
In 2014, A&O completed 177 bridge inspections. Within the first half of 2015
alone, their teams have completed almost 140 bridge inspections.
A&O inspection teams have faced challenges with highway traffic and
have endured sub-freezing conditions with sleet or snow to triple-
digit temperatures with the threat of heat exhaustion or dehydration.
A&O is required to meet one-month deadlines with each assignment and is
The five-mile long Virginia Dare Bridge, spanning Croatan Sound between Manns Harbor and Roanoke Island, was inspected by A&O in 2014. Three
teams of inspectors worked concurrently for three weeks to complete the inspection.
2015 Project of the Year Nomination:
NCDOT Bridge Inspections
“The in-depth assessment
performed by Alpha &
Omega Group [for the
Herbert Bonner Bridge]was
outstanding. The document
provided a realistic and
detailed summary on the
condition of the bridge as
well as actions needed to
hold the bridge until 2016.”
Thomas Drda, PE
Federal Highway Administration
Bridge Engineer
By providing information to NCDOT on areas of concern,
such as this damaged rail on a Catawba County bridge,
A&O recommends repairs, helps the state to extend the
life of each bridge, and improves public safety.
sometimes required to perform inspections on weekends, due to heavy truck
traffic volumes during the week. Inspections are scheduled with the safety of
inspectors and minimizing delays to the traveling public in mind. In addition
to working under difficult conditions, bridge inspectors must be aware of the
environmental issues of the location they are working in, as well as
alert to avoid disturbing wildlife or negatively impacting habitats.
By improving the existing structures, A&O can assist the state in delaying the
need for bridge replacement, keeping the cost to taxpayers down. A perfect
success story is the Herbert C. Bonner Bridge, which crosses the Oregon
Inlet between Bodie Island and Pea Island. Constant beach erosion, severe
weather, and high volumes of traffic had worn down the bridge, built in 1963.
A&O inspected and made recommendations for the bridge’s
structural improvement in 2007. The life of the bridge was able to be extended
until 2016, when a replacement will be built.
2. IMPROVING PUBLIC INFRASTRUCTURE Improving
public infrastructure is what bridge inspections are all about. Providing bi-
annual bridge inspections for NCDOT allows the continued in-service
maintenance of bridges across the state. This inspection and reporting
process provides critical bridge condition information to each NCDOT Division
Office in all 100 Counties of North Carolina. Providing condition information
allows NCDOT to provide the required maintenance to bridges in order to keep
the infrastructure in service and safe for North Carolina’s traveling residents
and visitors. Load rating analysis may be performed to determine
a structure’s capability to carry legal vehicular traffic in North Carolina. The
inspection and maintenance process currently has the overall state of bridge
health at 68.4%, up from ASCE’s rating of 62.4% in 2013. (http://www.ncdot.
gov/projects/ncbridges/). A&O has inspected more than 300 bridges since
June 2014 and more than 1400 bridges since 2000.
A&O inspection teams have
faced challenges with highway
traffic and have endured
sub-freezing conditions with
sleet or snow to triple-digit
temperatures with the
threat of heat exhaustion or
dehydration.
An A&O bridge inspector conducts an ultrasonic pulse velocity (UPV) test, which sends
an electronic signal through concrete to detect a void where concrete has deteriorated.
An A&O bridge inspector uses a small metal mallet to
“sound the element,” tapping lightly against the bridge
structure to identify deficiencies in the concrete. This
non-destructive inspection technique reduces the risk of
debris falling into the water.
ADVANCING TECHNOLOGY To attract high-tech companies
to North Carolina, the need for strong transportation infrastructure has never
been greater. Strong bridges allow trucks and heavy construction equipment to
bring supplies to their companies’ facilities as well as provide their employees a
dependable route to work. By helping to improve and maintain transportation
infrastructure, bridge inspections support the state’s goal of attracting
companies such as the Facebook Data Center in Rutherford County, located
near Forest City along US Highway 74, where A&O has performed bridge
inspections.
Additionally, A&O embraces the newest technology in its work by utilizing
Microsoft’s Surface Tablets to collect and record the condition of each
bridge element directly into the bridge reporting software created by
NCDOT. Surface Tablets enable our inspection teams to collect data, record
bridge element deficiencies, quantify needed repairs, include photographs,
and check and submit completed reports to NCDOT quickly. Hand-held
laser equipment is used to document bridge dimensions along with
tape measures and levels to accurately collect areas of deteriorating elements
for repair. The speed of inspection and use of the latest technology allows
A&O to complete the inspection process and provide NCDOT an electronic
report within five days for each of NCDOT’s 18,000 bridges and culverts
throughout the state.
An A&O bridge inspector uses a Microsoft Surface Tablet to
record data during a bridge inspection in Johnston County.
3. ENVIRONMENTAL RESPONSIBILITY A&O engineers and
bridge inspectors understand and take seriously their role in preserving North
Carolina’s natural environment. They see routine bi-annual inspections as a
means to maintain and preserve the state’s infrastructure without
increasing the volume of waste in landfills with concrete and steel debris that
would be generated by allowing bridges to deteriorate prematurely.
The bridge inspection teams are usually able to inspect bridges on foot without
disturbing the natural habitat of wildlife or vegetation. In some cases,
bridge access equipment is used to access the superstructure underside from
the bridge deck without disturbing the environment at all.
Boats are also used for inspecting bridges over large bodies of water with low
vertical clearance.
A&O bridge inspectors have demonstrated environmental responsibility in the
following specific ways:
• When encountering the threatened northern long-eared bat
in a Rutherford County inspection, they took steps to leave the natural
habitat of the animals undisturbed.
• Before beginning work on the Emerald Isle Bridge, AO prepared a
detailed work plan for a local environmental agency describing how
concrete core samples would be removed from the bridge, using vacuum
hoses and other means to prevent debris and dust from falling into the
Intracoastal Waterway.
• Inspectors monitor scour, or erosion caused by the constant movement
of water around the footing of bridge supports. They report their
findings so that measures can be taken to protect both the
bridge and the waterway.
AO engineers drill concrete core samples from the Emerald Isle Bridge,
vacuuming dust to keep it from falling into the Intracoastal Waterway.
Special equipment is used to access the underside of the
bridge deck without disturbing wildlife.
AO engineers were aware and alert when they
encountered the northern long-eared bat, a threatened
species, during a Rutherford County bridge inspection.
They were careful to leave its natural habitat
undisturbed.