Infrasense Scans Complex Interchange in Waterbury, Connecticut Using GPR
Posted: 2015-2-22
Source:
PR Web
Infrasense, Inc., a national leader in infrastructure nondestructive evaluations,
recently carried out subsurface investigations for 9 bridge decks, representing
nearly 700,000 square feet, in the "Waterbury Stacks" interchange. The
subsurface investigations were performed using vehicle-mounted high-speed
ground penetrating radar (GPR) to scan selected bridges within the complex
interchange. Unlike traditional inspection methods, these tests provide a
condition assessment of the reinforced concrete bridge decks without requiring
lane closures and with no disruption to traffic flow - a particular concern for the
highly trafficked bridges connecting Interstate 84 and Route 8 at the heart of
Waterbury.
Ground penetrating radar (GPR) data is collected at highway speeds to estimate
rebar depth, corrosion conditions and deteriorated concrete. The GPR data is
collected in a series of lines spaced 3 feet transversely across the width of the
deck, with each line representing a cross sectional slice of the deck at a
particular offset. Decks in good condition consist of strong and uniform radar
reflections from the rebar. GPR data with weak and inconsistent reflections
indicate rebar-level deterioration in the bridge deck. Infrasense uses its own
proprietary software to analyze and map this data to provide comprehensive
results for its clients.
A 2012 study carried out by an independent consultant for MnDOT evaluated the
accuracy of Infrasense's GPR results provided to the Minnesota DOT. The study
compared the predicted quantities for 12 decks surveyed by Infrasense against
subsequent construction repair quantities. The study found that, on average,
Infrasense’s predicted deterioration quantities were within 3.5 % of the
documented construction quantities.
Ground penetrating radar surveys provide transportation agencies with accurate
and comprehensive bridge deck condition information, enabling effective
preservation, rehabilitation, and replacement decisions. With large bridge deck
inventories, highway agencies have primarily relied on visual inspection at the
network level. Since the mechanisms of deterioration occur below the surface,
their manifestations are not readily seen in the visual inspections. As a result,
visual deck assessments are often inaccurate, and do not provide a sound basis
for planning repair and rehabilitation.
Traditionally, highway agencies have employed sounding (chain or hammer) to
identify delaminated areas for project-level rehab. Although sounding has
proven reliable, the labor and closures required for a sounding survey makes it
prohibitive for obtaining data of a large number of decks. Also, sounding is not
effective when there is an asphalt overlay. In response to these limitations, a
number of highway agencies have utilized alternative methods such as ground
penetrating radar.
About Infrasense, Inc.
Since 1987, Infrasense, Inc. has applied state-of-the-art technologies to address
the most difficult challenges in subsurface scanning. Infrasense’s engineers are
able to nondestructively extract critical information from a diverse range of
structures. In addition to providing ongoing subsurface evaluation services to
clients across the country, the firm has also conducted numerous research
programs to advance the field of subsurface detection and non-destructive
evaluation.
recently carried out subsurface investigations for 9 bridge decks, representing
nearly 700,000 square feet, in the "Waterbury Stacks" interchange. The
subsurface investigations were performed using vehicle-mounted high-speed
ground penetrating radar (GPR) to scan selected bridges within the complex
interchange. Unlike traditional inspection methods, these tests provide a
condition assessment of the reinforced concrete bridge decks without requiring
lane closures and with no disruption to traffic flow - a particular concern for the
highly trafficked bridges connecting Interstate 84 and Route 8 at the heart of
Waterbury.
Ground penetrating radar (GPR) data is collected at highway speeds to estimate
rebar depth, corrosion conditions and deteriorated concrete. The GPR data is
collected in a series of lines spaced 3 feet transversely across the width of the
deck, with each line representing a cross sectional slice of the deck at a
particular offset. Decks in good condition consist of strong and uniform radar
reflections from the rebar. GPR data with weak and inconsistent reflections
indicate rebar-level deterioration in the bridge deck. Infrasense uses its own
proprietary software to analyze and map this data to provide comprehensive
results for its clients.
A 2012 study carried out by an independent consultant for MnDOT evaluated the
accuracy of Infrasense's GPR results provided to the Minnesota DOT. The study
compared the predicted quantities for 12 decks surveyed by Infrasense against
subsequent construction repair quantities. The study found that, on average,
Infrasense’s predicted deterioration quantities were within 3.5 % of the
documented construction quantities.
Ground penetrating radar surveys provide transportation agencies with accurate
and comprehensive bridge deck condition information, enabling effective
preservation, rehabilitation, and replacement decisions. With large bridge deck
inventories, highway agencies have primarily relied on visual inspection at the
network level. Since the mechanisms of deterioration occur below the surface,
their manifestations are not readily seen in the visual inspections. As a result,
visual deck assessments are often inaccurate, and do not provide a sound basis
for planning repair and rehabilitation.
Traditionally, highway agencies have employed sounding (chain or hammer) to
identify delaminated areas for project-level rehab. Although sounding has
proven reliable, the labor and closures required for a sounding survey makes it
prohibitive for obtaining data of a large number of decks. Also, sounding is not
effective when there is an asphalt overlay. In response to these limitations, a
number of highway agencies have utilized alternative methods such as ground
penetrating radar.
About Infrasense, Inc.
Since 1987, Infrasense, Inc. has applied state-of-the-art technologies to address
the most difficult challenges in subsurface scanning. Infrasense’s engineers are
able to nondestructively extract critical information from a diverse range of
structures. In addition to providing ongoing subsurface evaluation services to
clients across the country, the firm has also conducted numerous research
programs to advance the field of subsurface detection and non-destructive
evaluation.
