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The Turner-Fairbank Highway Research Center
is the research arm of the Federal Highway Administration,
located in McLean, Virginia.
One of its laboratories, the Nondestructive Evaluation,
or NDE Center,
conducts research and development
on advanced sensing technologies
and on testing and evaluation techniques
to assess the condition of highway infrastructure assets,
such as bridges, pavements, and tunnels,
without impairing their future use.
As our transportation infrastructure continues to age,
accurately identifying areas that require maintenance
and repair is critical.
The research conducted by the NDE lab
provides solutions to these problems.
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Like medical x-rays, MRIs, and ultrasound tests,
the nondestructive testing of highway infrastructure
can be non-invasive and have the ability
to assess the condition of their materials and components
without disassembling or inflicting damage.
Today, my annual routine inspection
is mainly based on visual inspection
and manual sounding techniques.
However, over the last decade,
advancements in sensing and nondestructive techniques
has impacted highway industry.
Infrastructure owners are gaining more confidence
in the added value of using NDE technologies,
and are having better understanding
of their limitations,
which can be credited to the close collaboration
and cooperation among owners, researchers,
technology providers, and policymakers.
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The NDE lab is equipped
with the state-of-the-art NDE technologies
for both concrete and steel structures.
For example, ground-penetrating radar,
impact-echo, surface wave testing,
electrical resistivity, and infrared thermography
are all used to inspect concrete structures.
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The NDE lab also does research on technologies
that can be applied to evaluate steel structures
using conventional ultrasonic equipment,
phased array ultrasonic equipment,
and full matrix capture ultrasonic equipment.
The lab also performs finite element modeling
and other numerical simulations
to better understand the NDE measurements
and to optimize the NDE tools in use.
The NDE lab has an extensive collection
of concrete and steel specimens
salvaged from in-service highway structures.
For example, two pre-stressed girders from a bridge
on Maryland State Route 90,
a 30-foot length of bridge deck from Haymarket, Virginia,
and a number of sections
of the Arlington Memorial Bridge deck.
These samples provide researchers
with real world, full-scale test specimens.
Our focus in the FHWA NDE lab is twofold.
Our first focus is conducting research
to improve the state of practice of NDE technologies
to make them automated and more reliable.
One of the developed tools at the NDE lab
is a magnetic rover to quantify the extent of corrosion
in concrete, pre-stressed girders.
The system consists of two strong permanent magnets
and 64 sensors that measure magnetic field variations.
The information gathered can then be used by owners
to make risk-based decisions
regarding their infrastructure assets.
NDE lab researchers also developed
a robotic non-contact acoustic system,
with ultrasonic speakers and MEMS microphones
for high-speed evaluation of bridge decks,
which reduces traffic delays and increases safety
when collecting data.
Our second focus is to fuse data
from multiple NDE modalities to improve data reliability,
to investigate effective visualization approaches
for more intuitive data interpretation,
and also extraction of actionable information
from the collected data.
Investigating effective visualization approaches,
such as augmented reality,
to superimpose the NDE measurements
on an image of the physical structure,
help provide more intuitive data interpretation
for asset owners.
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The NDE lab is also exploring new data analysis approaches,
such as artificial intelligence algorithms.
The goal is to automatically identify
patterns and relationships implicit within the data,
then leverage these patterns to automate predictions
of the future condition of pavements
and structural components.
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The NDE program is developing tools
to assist bridge and highway owners,
researchers, and industry,
to better understand the operation
and physical principles of NDE methods.
One of these tools is the NDE Web Manual
that provides users with unbiased,
comprehensive information about different NDE technologies
for bridges, pavements, and tunnels.
It also assists the DOTs
with proper selection of NDE technologies
based on their specific problem and application.
A recent addition to the NDE Web Manual
is an interactive, virtual NDE lab environment
that allows users to explore various technologies
through interactive data and simulation portals.
It also offers realistic case studies
that expose users to decision scenarios
related to the design and deployment
of various structural health monitoring systems.
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Although current NDE tools and technologies
are useful and promising
at locating and detecting potential defects
in transportation infrastructure components,
their use often requires lane closures
to collect data in the field,
thus increasing work zone safety concerns
and traffic delays.
The next generation of NDE tools
will employ and fuse multiple technologies
to collect bridge structure condition data
at traffic speed via remote sensing
and non-contact equipment,
unmanned aerial systems,
and other autonomous and remote-operated technologies
that can communicate data in real time.
All these tools would talk to each other
using advanced IT technologies.
Data would be instantaneously analyzed, fused, visualized,
and transmitted for quick interpretation
by bridge engineers,
so decisions regarding health of individual bridge elements
or the overall structure can be expedited.
For instance, in the future,
UASes can be deployed first
to perform a quick scan of the entire infrastructure.
UASes are equipped with infrared thermography cameras
to produce images of the surface temperature distribution
over a large area.
The thermal images can reveal subsurface damage
in the concrete that manifests as temperature variation
at the surface of the concrete.
Data captured by UASes will be transmitted
to the data center and analyzed in real time.
Once a delamination is detected,
it is noted by an alarm.
After review by the owner,
the results could then be communicated to the van,
climber robot, and the crawler robot,
so they start collecting detailed NDE measurements.
The van would be equipped
with advanced traffic speed NDE technologies.
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The subsurface damage
typical in reinforced concrete bridge decks
is commonly known as delamination.
The delamination is produced by the expansion
of corroded reinforcing steel in the concrete.
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The crawler robot, which is a magnetic-based NDE tool,
would inspect cables to detect any corrosion
or fracture along the cable.
Data would then be transmitted and analyzed in real time.
The climber robot would also be equipped
with advanced NDE technologies
to evaluate the condition of piers.
Data captured by different NDE tools
would be analyzed in real time and fused together
to provide more reliable and in-depth information
to the bridge owners.
Once the defect is detected,
the alarm would go on and information would be sent
to the data center.
After confirmation by the owner,
the results could then be communicated
to the repair robot,
so it can go to those locations that need repair
and complete the repair.
For example, inject epoxy or grout.
As the technologies for highway infrastructure mature
and our knowledge of data analysis and extraction
of actionable information advances,
the owners will be more eager to utilize NDE technologies
as part of their routine inspection
and asset management.
So the technology of the future should advance toward systems
that are autonomous, resilient to any environmental condition,
reliable, and cost-effective.
And it should provide real-time intelligent information
to the owners.
We have made a great leap in the NDE technologies
in the last two decades,
and I'm certain that within the next few years
we will be able to deliver standardized NDE technologies
that would help our infrastructure owners
make intelligent decisions about managing their assets.
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