5 reasons DOTs are using GPR to evaluate pavements

Ground penetrating radar (GPR) is an NDE technique that operates by transmitting short pulses of electromagnetic energy into the pavement structure from an antenna. These pulses reflect off of subsurface layers and objects providing a record of the conditions and properties. Infrasense uses a GSSI vehicle-based GPR system for data collection, in-house proprietary software for data analysis, and provides results in formats compatible with CAD and ArcGIS. GPR has a number of benefits for pavement evaluation that an increasing number of DOTs are starting to take advantage of. Below are 5 of the key reasons DOTs are currently using GPR to evaluate pavements.

1.  Provides continuous pavement structure information.

GPR can detect the bound and unbound layer thicknesses. The layers can be plotted continuously providing a comprehensive depiction of the pavement structure, which can facilitate a rehab design.

Pavement Structure Information 

2. No lane closures required.

GPR pavement surveys are carried out at driving speeds, so no lane closures are required.

No Lane Closures 

3. Integrates with FWD testing to provide pavement layer moduli and remaining life values  

Pavement layer thicknesses provided at FWD test locations via GPS coordinate synchronization.

FWD & GPR Integration

4. Detects subsurface voids and presence of relatively high moisture content

Voids and areas of relatively high moisture content can be quantified and mapped. The maps are used to direct localized confirmative tests and ultimately facilitate a rehab design.

Subsurface Voids

5. QA of new HMA pavement 

New HMA pavements can be surveyed with GPR to provide a comprehensive map of relative density. This map can be used to direct coring and nuclear/ nonnuclear gauge testing. 

comprehensive map of relative density

Infrasense uses GPR to Evaluate 28 Ohio Bridge Decks

Infrasense, Inc., a national leader in infrastructure nondestructive evaluations, recently completed ground penetrating radar surveys of 28 bridge decks in Ohio. These bridges represent nearly 131,000 square feet throughout the northwest section of the state. The ground penetrating radar surveys were carried out at driving speeds, so no closures were required and traffic flow was not disrupted. The GPR surveys provide a deterioration quantity and map for each reinforced concrete bridge deck and the approach slabs. Additionally, visual inspections of the deck undersides and high-resolution video surveys of the wearing surface conditions were completed for each deck. ODOT's Planning and Engineering Division will utilize the deck condition results to prioritize future preservation, maintenance, rehabilitation, and deck replacement funding.

bridge deck surveyed with GPR in Ohio

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 software to analyze and map this data to provide comprehensive results for its clients.

Ground penetrating radar surveys provide transportation agencies with accurate and comprehensive bridge deck condition information, enabling effective preservation, rehabilitation, and replacement decisions. 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, including ODOT, have utilized alternative methods such as ground penetrating radar.

The 5 Steps to Map Bridge Deck Delamination with Infrared Thermography

Infrared Thermography is becoming a more mainstream method for mapping delaminations in bridge decks due to increasing traffic volumes, and growing demand for accurate and comprehensive condition information. Below is a simple 5-step explanation of how infrared is used to evaluate bridge decks.

Step 1: You need the sun to shine!

Delaminations act as a thermal barrier, so when the sun heats up the deck, these areas show up as “hot spots” in the infrared data.

Infrared Thermography of Bridge Deck

 

Step 2: Infrared and visual images are collected using a vehicle-based system.

Data is collected at driving speed (up to 50 mph), which eliminates the need for road closures

Infrared Thermography Vehicle 

Step 3: Infrared images are stitched together to create a plan-view mosaic of the deck.

The white blotchy areas are “hot spots” and correspond with subsurface delaminations.

IR Scanning Data

 

Step 4: The “hot spots”, not related to surface features (staining, patching, etc.), are mapped and quantified.

IR Analyzed data

 

Step 5: Delamination maps are exported to a CADD compatible format and used for rehab design.

IR data

Infrasense, Inc. Surveys Hundreds of Bridge Decks with Ground Penetrating Radar in Montana, and Infrared and GPR in Wisconsin

GPR Bridge Deck Scanning in Montana, GPR Bridge Deck, NDT

Infrasense, Inc., a national leader in infrastructure nondestructive evaluations, has recently completed GPR data collection for 116 bridge decks throughout Montana, covering nearly 900,000 square feet. The Infrasense survey crew is currently working to collect infrared thermography data on 119 bridge decks across 4 different regions of Wisconsin. The total deck area for the Wisconsin work amounts to over 1 million square feet, which would have taken months to evaluate using traditional methods such as sounding. But these decks are surveyed in only a few weeks with the Infrasense subsurface scanning system. Following data collection, the NDE data is processed, and subsurface damage is then quantified and mapped using Infrasense’s proprietary software systems. The final delamination/ deterioration quantities and maps allow bridge engineers and managers to both prioritize future repair, rehab, and replacement efforts, as well as scope out the extent of repair for contracts being put out to bid.

Ground penetrating radar (GPR) data is collected at highway speeds, making it the fastest NDT technology 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.

The infrared data is collected in a series of passes across each deck, with each pass covering a deck width of between 12 and 15 feet. Surveys are performed at normal driving speeds to prevent lane closures and traffic disruptions. During the survey, regular visual data is collected synchronously with the infrared data, so that surface features such as staining and patching can be differentiated and mapped in the infrared images.

Ground penetrating radar surveys and infrared data 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. Since the mechanisms of deterioration occur below the surface, subsurface investigation is most effective to evaluate the estimated lifetime of these bridges.

Highway agencies have begun to move away from employing 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.

 

5 Reasons DOTs Are Scanning Their Bridge Decks with GPR and Infrared

Nondestructive testing (NDT) methods for evaluating the conditions of bridge decks include ground penetrating radar (GPR) and infrared thermography (IR). GPR transmits pulses of energy into a bridge deck and measures the strength of the reflection off of the structural layers. Areas showing relatively weak reflections are associated with concrete deterioration and correlate well with corrosion potential and high chloride content. Infrared thermography is different in that it measures the surface temperature of a bridge deck. Areas with relatively high temperatures are associated with delaminations within the concrete. With infrastructure conditions worsening and funding levels remaining stagnant, high-speed evaluation methods are beginning to gain traction with an increasing number of transportation agencies.

GPR Bridge Deck, Nondestructive testing Bridge Deck

Here are 5 key reasons why.

1. Reduced contingency funding, allowing agencies to rehab more decks with a given budget.

Duane Green, maintenance operations engineer in MnDOT’s metro district, said GPR is a useful planning tool for the department... It “helps us wisely use the repair dollars we have to use,” he said. “I don’t have to have quite as big a contingency factor. … Instead of being in the ballpark [for planning purposes], I am in the infield now.”

Read more: http://finance-commerce.com/2011/11/mndot-using-ground-penetrating-radar-to-inspect-bridges/#ixzz3bXq5fhjZ 

2. No lane closures are required, keeping the traffic moving and taxpayers happy.

Proven in past projects: http://www.prweb.com/releases/2015/04/prweb12682055.htm

3. Data-driven prioritization of preservation, repair, rehab, and replacement efforts.

“There are a number of advantages of GPR technology for bridge inspection, and the method is particularly well-suited to prioritizing for budgeting purposes.” As described by Dr. Roger Roberts (GPR expert at GSSI) in a recent article from STRUCTURE magazine titled “Inside the Bridge Inspection Toolbox”.

Read more: http://www.structuremag.org/?p=8064

4. Ability to detect damages below the surface and repair before potholes appear.

Learn more by watching this video: https://www.youtube.com/watch?v=OWkMUtjSuKE

5. Condition quantities and maps can be provided for 100s of bridge decks in just weeks

Reliable and comprehensive condition information is critical towards a successful bridge management program.  The accuracy of this information translates directly to the efficiency at which rehab and replacement funds are spent. Traditional methods of chain dragging, hammer sounding and visual inspection are highly subjective, labor intensive, and provide limited detection capability.  The use of emerging high-speed scanning technologies, such as GPR and infrared, provides measurable data that, with proper analysis, can be converted into actionable information. For bridge decks this information comes in the form of delamination, deterioration, spalling, and patching quantities and maps.

Sources: http://www.fhwa.dot.gov/goshrp2/Solutions/Renewal/R06A/Nondestructive_Testing_for_Concrete_Bridge_Decks
http://www.fhwa.dot.gov/bridge/deficient.cf

Infrasense, Inc. to Begin Ground Penetrating Radar Scanning and Infrared Scanning of Bridge Decks this Spring

Infrasense, Inc., a national leader in ground penetrating radar and infrared thermography bridge deck surveys, has begun a busy data collection season, with many nondestructive testing projects scheduled across the United States. In total, Infrasense plans to scan nearly 350 bridge decks this spring and early summer, with projects ranging from Connecticut to Montana. Infrasense also has upcoming pavement structure evaluation projects across the U.S. GPR pavement applications include subsurface void and moisture detection, layer thicknesses, and density of new HMA pavements.

Infrasense has played a key role in the development and implementation of GPR, Infrared Thermography, and other NDT methods for evaluating transportation infrastructure over the past 27 years. One of the most common applications of the ground penetrating radar technology is the determination of pavement structure layer thicknesses. Unlike traditional coring, GPR requires no lane closures and provides a timely and cost-effective means of obtaining continuous thickness data. This data is accurate, (within 10% of core values), and may be used for network-level pavement management or project-level rehabilitation design, and provides the necessary information in FWD analyses to calculate the remaining lifespan of an existing pavement. GPR data also reveals patterns and anomalies in pavement structure that often go unnoticed using traditional coring techniques.

Infrasense surveys have covered over thousands of lane miles of pavement. Projects range in size from a few miles in length, to over 1,500 lane miles of county roads in North Dakota working with the North Dakota State University's Upper Great Plains Transportation Institute.http://www.ugpti.org/downloads/road_needs/testing.php

Nondestructive scanning data is also collected on bridge decks. Ground Penetrating Radar data is used to identify corrosion induced delamination, and to estimate rebar depth. Decks in good condition consist of strong and uniform radar reflections from the rebar, whereas weak and inconsistent reflections indicate rebar-level bridge deck deterioration.

Infrared Thermography data is collected to directly identify and locate delaminations in the concrete at the reinforcing steel. Infrared data is collected in a series of passes across each deck, with each pass covering a deck width of between 12 and 15 feet. The survey produces a series of infrared images collected every foot of vehicle travel. During the survey, delaminations that heat unevenly due to thin voids at the reinforcing steel appear in the IR image as brighter "hotspots". Because many of these decks have overlays, the reinforcing can be 4-5 inches from the surface, and sounding is not always capable of detecting delamination at this depth. Deck surface conditions, such as patching and spalling, are mapped and quantified using a high-resolution video system operated concurrently with the infrared survey.

Infrasense Participates in the 2015 Western Bridge Preservation Partnership Meeting and the 9th International Conference on Managing Pavement Assets

Infrasense recently attended the 2015 Western Bridge Preservation Partnership meeting in Portland, Oregon. The meeting was held to discuss bridge preservation practices that are currently being used. The gathering also provided a forum to discuss bridge preservation strategies-including treatments; management; inspection; improvements in research, design, specifications, and materials; and to promote the benefits of Bridge Preservation through education and application.

The Western Bridge Preservation Partnership is a regional forum comprised of bridge practitioners from State and Local Agencies, Contractors, Consultants, Suppliers, Academia, and Federal Government Officials in a sharing of bridge preservation practices throughout the Western Region. Topics of discussion included bridge deck evaluation methods, deck preservation treatments, superstructure inspections and preventative coatings, maintenance practices, corrosion mitigation, and hydro-demolition of bridge decks. The meeting also included presentations from industry leaders about bridge preservation management, amongst other technical presentations.

Adam Carmichael at WBPP 2015  

Adam Carmichael at WBPP 2015

 

Adam Carmichael, Infrasense’s Operations Manager, exhibited at the meeting, and discussed Infrasense’s high-speed scanning capabilities used to map subsurface conditions of roads and bridges. There was a great deal of interest in how different State transportation agencies are currently using nondestructive methods such as ground penetrating radar and infrared thermography. A large part of this conversation is the use of nondestructive testing data to prioritize bridge deck preservation decisions; particularly with States facing increasingly limited funding.

Infrasense also attended the 9th International Conference on Managing Pavement Assets in Alexandria, Virginia. The Transportation Research Board (TRB), Virginia Department of Transportation (VDOT), Virginia Tech, Federal Highway Administration (FHWA), American Association of State Highway and Transportation Officials (AASHTO), and the World Road Association all helped to organize the 9th International Conference on Managing Pavement Assets (ICMPA9). The conference’s main theme was to move pavement management beyond the short-term: embracing innovation and addressing sustainability, accountability, and improved performance.

A Pavement Management System (PMS) incudes a database of all information about each pavement segment in a jurisdiction (city/state/county), predictive models that projects how each pavement segment will deteriorate over time, and optimization and planning procedures for determining maintenance and rehabilitation (M&R) needs and costs over an extended time period. Typically the condition of the pavement is assessed based on what is seen on the surface- cracking, rutting, and roughness. Traditionally, continuous pavement layer thickness measurements have not been included in the deterioration modeling and M&R projections.

This conference discussed new aspects of a pavement management system; a device for measuring the deflection of pavement at driving speed, or Traffic Speed Deflectometer (TSD). This device now provides information on the pavement strength, which can accompany the data on surface condition. That strength information benefits from the availability of the pavement layer thickness data that Infrasense provides.

The Friday following the ICMPA9, Ken Maser met with the Technical Advisory Committee (TAC) to discuss a pooled funded study with the objective to evaluate the TSD device and to develop methods for incorporating the data into Pavement Management Systems. Infrasense is involved in this study through an upcoming project with the Idaho Transportation Department (ITD). This project will collect data from both GPR and TSD methods on a 518-mile loop and determine the pavements structural capacity.

Summer Interns

Summer may mean sun, flip flops  and beaches, but here at Infrasense it also means interns, and boy do we have them! This summer we have four new additions. We are so happy to welcome them! 

Johnpatrick Connors- Junior Staff Engineer

Johnpatrick Connors- Junior Staff Engineer

JP is a rising senior at Worcester Polytechnic Institute, something about the combination of Infrasense and WPI students creates a perfect pair! JP is majoring in Civil Engineering with a focus on structures. He also has a minor in History. At WPI JP’s favorite class so far has been Design of Steel Structures. JP previously interned at Simpson Gumpertz & Heger where he assisted with failure investigations and new construction design work. He has also been a research assistant at WPI to his professors.

JP is from Sudbury Massachusetts. His interests include; traveling, discovering coffee shops, reading, and running. JP hopes to someday travel to Italy, mostly for the food. JP is Bilingual and spricht Deutsch (Speaks German!). Maybe this summer we will learn some from him!

Eric Hinds- Junior Staff Engineer

Eric Hinds- Junior Staff Engineer

Eric is a rising senior at UMass Lowell. He is majoring in Civil and Environmental Engineering. At UMass Lowell Eric’s favorite course so far has been the Strength of Materials course. Eric has 5+ years of construction experience under his belt. He also worked on Nondestructive Evaluation research at UMass Lowell.

Eric is from Andover Massachusetts.  He enjoys hiking and backpacking, he also enjoys the mountains in the winter time by snowboarding. Eric would love to visit the Rocky Mountains in Colorado and continue his hobbies on a larger scale. Eric likes cooking in his spare time and also attending concerts. Eric stands by his heritage by playing the bagpipes, a uniques skill we are all a little jealous about.   

Ryan Grover- Junior Staff Engineer

Ryan Grover- Junior Staff Engineer

Ryan is a rising senior at the University of New Hampshire. He is majoring in Civil Engineering. Ryan’s favorite course so far has been his Structural Analysis course. Ryan is a math and science enthusiast and has used this passion to almost complete the engineering program at UNH. Ryan also has experience in constructing homes from a visit to El Salvador where he and his team completed 8 homes.    

Ryan is from Keene New Hampshire. He enjoys to surf, especially in California, which top his list of favorite places to travel to. Ryan’s hobbies include fishing, camping and snowboarding. Ryan and his Mom have a new special Mother’s day tradition of skydiving each year- Ryan has jumped once so far but, he is excited for the years to come.  

Olivia Prentiss- Marketing & Business Development Intern

Olivia Prentiss- Marketing & Business Development Intern

Olivia is a rising senior at Bentley University. She is majoring in Marketing  and Global Perspectives. She also is working towards a management minor. Olivia’s favorite class that she has taken at Bentley so far has been her advertising course, where she had the chance to work first hand with HubSpot and American Program Bureau. Olivia has previously interned at EPS Communications and Konica Minolta both in the marketing fields. 

Olivia is from Essex Massachusetts. She has a passion for the beach and the ocean. She also enjoys reading, going to concerts, and outdoor activities. Olivia spent her fall semester in Barcelona Spain, which could only be described as an experience of a lifetime. While in Europe she traveled to 7 countries and countless cities.

 

 

Infrasense's Adam Carmichael Is Attending the SEBPP Meeting

If you're attending the Southeast Bridge Preservation Partnership Meeting being held in Montgomery, Alabama,  come stop by the newly redesigned Infrasense exhibit. Operations Manager Adam Carmichael will be in attendance, looking for new ways Infrasense can help improve maintenance procedures in the Southeast.

We also plan on attending the Western, Midwest, and Northeast Meetings, to be held throughout the year. So if you're planning on attending any of these meetings, we hope to see you there!

Infrasense Debuts New Website, Logo

The Infrasense team is excited to officially debut our new website and logo!

Our new logo is a simple and stylish representation of the subsurface scanning and mapping services that we offer. It subtly references key elements of both our previous logo and the principles of ground penetrating radar.

Our new website offers a more streamlined experience to visitors. Infrasense is a small engineering firm working with highly specialized tools, and we think it's important that you know just "Who We Are"! We offer a wide range of nondestructive testing services, and visitors can learn about "What We Do" in our primary applications to bridge decks, pavements, utility detection, and research and consulting. While Infrasense is excited about this step forward, we know that our history is just as important, and "Where We've Been" really provides us with the experience and expertise to continue providing clients with top notch service and results.

We hope you enjoy the updates, and look forward to working together in the future!