Author: Lorella Angelini, Angelini Consulting Services, LLC

Second from the right: Rod Thornton with MDOT-SHA

Rod Thornton is the Maryland Department of Transportation – State Highway Administration’s (MDOT-SHA) Deputy Director of Structure Inspection and Remedial Engineering Division.  In addition to his responsibilities with MDOT-SHA, he is active with TSP2 being the Vice-Chair of the Northeast Bridge Preservation Partnership Committee. I had the opportunity to ask Rod a few questions about bridge preservation strategies at Maryland DOT.

What does bridge preservation entail at MDOT-SHA?

It is comprised of a number of programs that are all directed to preserving the integrity of the original bridges and eliminating emergency repairs.

A key program concerns bridge painting. The program, which advertises $12 million worth of painting projects every year, does not simply entail painting steel structural elements, but it also includes repairing deteriorated critical areas of the girders by plating, replacing leaking joint seals, and installing troughs under roadway joints.  This type of preservation work is included into the paint contract since paint scaffolding provides easy access to the areas to be repaired. By performing preservation work in parallel with painting, we eliminate the need to return to do these repairs in a following stage, which results in less of an impact to traffic and cost savings.  Funds above $12 million are added to the paint program in order to perform preservation activities.

Plating over severely deteriorated areas of a structural element, such as a beam, preserves the structural integrity of the element but also improves how long the paint system will last. The new “retrofit” plate provides a smooth surface that can be prepped to have the correct profile for proper paint adhesion. It is well-known that the long-term adhesion of a paint primer may be prevented if rust and other imperfections are not completely removed during the blast cleaning process and a proper profile of the blasted steel is not achieved. A good adhesion of the primer is essential for the intermediate coat and final coat to work.  Plating over the pitted areas of a beam with new steel allows for the creation of a good paintable surface profile, which in turn increases the longevity of the paint system. In areas that are subjected to a lot of moisture, like finger joints, the non-structural “retrofit” plates provide a layer of sacrificial steel while improving the adhesion of the paint.

Our paint program performs well, beyond the expected 20 years of steel protection. We are getting anywhere from 25 to 30 years out of the program.  The color of the top coat may fade, but the paint system still provides the steel protection that is needed to prevent corrosion.

Another important bridge preservation program at MD-SHA entails the use of latex-modified concrete overlays in order to preserve the deck thus avoiding or delaying its replacement.  The process starts with an evaluation of the chloride levels at the various depths of the deck. If a deck is in fair condition with concentration of chlorides near or just beneath the top mat of the deck reinforcement, we remove chloride-contaminated areas through hydrodemolition and we then cast a new latex-modified concrete overlay.  Since the early ‘70s, MDOT-SHA has required both the bottom and top rebar mats to be epoxy coated. Epoxy protects bars from corrosion induced by chlorides thus making it possible to reconstruct parts of the deck rather than replacing it.

MDOT-SHA is currently working to determine the best preservation actions for the old deck parapets that have high chloride concentration. We are looking into new types of sealers that contain chloride inhibitors to treat these parapets when the deck is partially reconstructed using latex-modified concrete thus preventing their replacement.

Another top preservation program at MD-SHA entails the installation of troughs under roadway joints where the seal is in NBI condition state 4 and 3.  We have set up a dedicated “open-ended” contract that allows us to assign a number of bridges to a contractor and get the trough installed once a bridge is identified. We also have a dedicated “open-ended” contract that allows us to wrap and strengthen the concrete structural elements of the substructure, such as caps and columns, with E-glass fiber reinforcement and coat these surfaces with an aliphatic polyurethane coating. Typically, we only wrap columns that are close, or adjacent, to roadways, thus creating a permanent water barrier from the salt spray generated by vehicles traveling past.

Since roadway joints are a source of deterioration for many elements of the substructure, such as bearings and beam ends, our newly designed bridges are built with no roadway joints or in a very limited number.

The last preservation program I would like to mention entails improving the protection of the steel tendons placed at the bottom of pre-stressed girders. We require a 4” clearance from the outside face of the girder instead of just meeting the 3” concrete cover required by AASHTO.  The additional clearance ensures that the tendons get adequately covered with concrete. There are known tolerances in casting of pre-stressed members that could end up reducing the cover of steel tendons that are close to the exterior surface.  We also include a design modification that increases the slope of the bottom flanges of AASHTO concrete girders so as to prevent accumulation of debris, bird droppings or bird nests.

Could you outline the key points of the bridge preservation strategy at Maryland SHA?

I would summarize the strategy in three points.  The first one involves the evaluation of Structurally Deficient (SD) and Fair rated bridges on the entire highway system with the goal to properly intervene on SD bridges and to prevent Fair rated bridges from becoming SD.  Every year two managers, one from the design and the other from the maintenance side of the bridge office, visit all bridges that are rated SD and also those bridges that had been rated 5 for one or more items (deck, superstructure, or the substructure) for more than 10 years. Once all these bridges have been looked at, we determine whether they are candidates for maintenance actions, preservation activities, major rehabilitation, or replacement. In doing so, we monitor all bridges that are in bad condition and determine actions to be implemented and scheduled.

A second element of the strategy entails examining common design or construction details that cause maintenance issues or are linked to potential deterioration problems.  If in the inspection reports there are details that show the presence of a recurring bridge defect, then proper recommendations are made to the designers so as to eliminate it. As an example, in the 1960s they used to weld stiffeners halfway from the top to the bottom of steel girders’ diaphragms. Once we recognized that these stiffeners induced fatigue cracking over 10 – 15 years, we informed the design team so as to find a more effective solution. A recurrent issue entails the accelerated deterioration that we experience with galvanized corrugated metal pipes used to carry water runoff with high concentrations of chlorides. There are many more examples of issues found in the field resulting in design changes, such as poorly performing roadway joint systems, multi plank bridge deck details, and parapet details.  Through the constant communication with the design office we were able to improve what is being designed for our new bridges.

The third element of our strategy calls for an actual and effective communication between the bridge design team and the office I am in charge of, which entails inspection, construction, and engineering design for maintenance.  We are in constant communication and we work together to decide whether bridges should be preserved thorough minor rehabilitation, major rehabilitation or replacement.  In principle, we can save and keep any bridge if enough money is available, but there are cases where it is not economical to rehabilitate a bridge.  When we decide to make a major investment to rehabilitate a bridge, the design team should agree that no future plans are going to be made to replace or enhance that bridge.  On the opposite, if the design team programs a bridge for replacement, then the maintenance team will focus on safety repairs only, since there is no reason to spend money on a bridge that will not be around for much longer.  Maintenance preservation actions are a priority for those bridges that are intended to be kept in service for a long time.  A lot of engineering judgement and experience is requested to know when to intervene and perform repairs and where we may have capacity and safety issues, such as beams not capable to carry the load or pieces of concrete falling on vehicles, if we do not intervene. This mix of engineering knowledge and experience is an essential component to ensure public safety, which is our most important goal.

What are your bridge preservation goals, both short and long term?

Our short term bridge preservation goal is to comply with the Governor’s mandate to reduce the number of Structurally Deficient bridges to zero. We are going to achieve this goal by combining repair, rehabilitation, and design actions. (Ed. Note: Out of the 2567 bridges managed by Maryland SHA, 67 are classified as Structurally Deficient, corresponding to 3% of the total).

Extending the service life of bridges is our long-term goal. If we can get 20 more years from a bridge by doing preservation actions, it makes sense to perform them.  Preservation actions can vary. If a bridge has a deck that is in fair condition with 20 more years of life in it, we focus on the key bridge elements that may need preservation, such as beams and substructure. If we prolong the service life of these elements, we eliminate the need to replace the bridge in the short term and can wait until the deck needs to be replaced. By bringing bridges to Fair or better condition, we extend their service life and have time to focus on those bridges that are in critical conditions and cannot be expected to last long without a large capital investments. We perform holding actions to ensure the safety of the traveling public.

Which challenges have Maryland SHA encountered in the implementation of the bridge preservation strategy?

We have an issue with environmental permitting, which is an impediment for pressure washing.

Other States have been able to get an agreement with their environmental people, for example scheduling power washing during heavy rain. In Maryland we can power wash only a limited number of bridges provided that we collect water.  Grime, grit, debris, and oils pollute water during power washing thus making water a hazardous material that is cost-prohibited to collect. As a consequence, it is difficult for us to maintain clean critical structural elements, such as trusses, that collect a lot of debris.

Do you have a success story that you would like to highlight?

In addition to the paint program, of which I have already spoken, I would like to mention the paved pipe invert contract.

We have restored over 300 galvanized corrugated metal pipes by installing a new reinforced grout invert.  The hoop design of the pipe is re-established by this structural design methodology which essentially consists of welding steel reinforcing bars in a pattern longitudinally and transversely along the inside length of the pipe and then pouring a 4” thick concrete grout invert over top. By adopting this methodology, we have repaired pipes anywhere from 3 ft to 20 ft in diameter located under major Interstates or throughout our highway system.  By not having to replace these pipes, we have saved a lot of money.  The typical cost of the grout repair method is $40/SF, which is typically 20+ times less costly than replacement.  We started by paving the worst pipes and we will continue until we have paved 1300 + pipes.

In my opinion a big bridge preservation success story in Maryland is arriving to the point of having sustained funding. We have always had funding for maintenance and repair, but it was a one-shot approach. We now have funding that allows for broadening the use of preservation actions and setting up systematic programs. The recent gas tax imposed by the State has been a tremendous windfall for the highway program in Maryland. It has allowed us to focus on the Governor’s goals to achieve zero SD bridges and to perform all improvements that are going on in the entire highway system here in Maryland.

How can TSP2 assist you with reaching your bridge preservation goals?

TSP2 is giving me a unique opportunity to develop personal relationships in the bridge preservation community. I can connect with representatives from other States to find out what their programs are like, what processes they follow, and what products they use.

All States are trying to achieve common bridge preservation goals as cost effectively as possible and with the least impact to the travelling public. TSP2 provides the means to achieve these goals by learning and replicating what the different States have done successfully.

LINKS

NCHRP Project 20 68A, Scan 15-03

Successful Preservation Practices For Steel Bridge Coatings

http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP20-68A_15-03.pdf

SHA Paved Invert Specifications

https://www.roads.maryland.gov/OBD/11-08_SR-PI.pdf

John Buxton with Maine DOT

Author: Lorella Angelini, Angelini Consulting Services, LLC
I recently spoke with John Buxton, Bridge Maintenance Engineer / Deputy Chief Engineer at Maine DOT.  He is in charge of the Bridge and Structures Maintenance Division at the Bureau of Maintenance and Operations. In addition, he is connected to the executive office as the Deputy Chief Engineer. John is fully committed to bridge preservation. His many years of experience in this field make him a go-to person with TSP2.

What does bridge preservation entail at Maine DOT?
Bridge preservation currently represents 70% of Maine DOT’s maintenance budget. While in the past we used to do a lot of rehabilitation and restoration type of work, currently preservation is the primary focus for the maintenance department. Preservation entails activities such as replacing and repairing joints, making sure that all joints are sealed, sealing concrete with water repellents, painting bearings and beam ends, and keeping concrete wearing surfaces in good condition. We are trying to address the deterioration of bridge elements before it becomes a problem. It is evident that it is better to spend a few dollars in preservation than thousands of dollars in restoration.

Does your 70% of maintenance budget include all preservation expenditures at Maine DOT?
In addition to maintenance, also the capital side has a budget for preservation activities, which mainly entail full painting projects. We are treating concrete with silanes, not only the deck but also vertical surfaces, such as piers adjacent to travel ways, back walls, and all exposed concrete.

The capital money is obviously not as aggressive in preservation as maintenance money. The capital side probably spends 25 – 30 % of their funds in preservation while the rest is reconstruction and bridge replacement.

Getting the capital people, who focus on new bridge construction, to invest funds on preservation activities has been a major shift in the way Maine DOT operates.  It is a combination of preservation, construction and reconstruction that allows maximizing investments for the bridge infrastructure.

What are the key points of the bridge preservation strategy at Maine DOT?
Our main strategy is to keep bridges in good condition by doing preservation activities. We are getting out of the “worst first” type of mentality, even though we continue to take care of bridges that are deteriorated beyond the practical maintenance point.

If you talk with other representatives from the TSP2 Bridge Preservation Partnership, you will find that they are using the same approach.

Do you have any statistics that show the benefits of a bridge preservation strategy?
The benefit of preservation is probably one of the hardest things to capture. For example, when you seal concrete it is hard, almost impossible to predict, whether the concrete is preserved for 20 or 25 years. In terms of NBI Bridge Inspection Ratings, when you seal the concrete of a pier, you do not change the rating of the pier. Let’s say the pier is in a condition state 6. By sealing the concrete you hopefully have kept the pier in that condition state for a longer time, which does not show up in graphs or statistics. It is really difficult to quantify the benefits of preservation actions.

Is it challenging to convince people of the benefits of preservations?
Yes, building a new bridge always carry the headlines. However, the political flavor has changed in Maine and around the Nation. People understand that it is worth preserving bridges, especially when they see the tremendous cost for a new bridge. Spending a fraction of that cost to do actions that can preserve an older bridge and get 30 – 40 more years of life out of it is evidently the proper way to go in most cases.

What are your goals with bridge preservation?
In line with the National Highway System guidelines, our primary goal is to eliminate all condition 4 , corresponding to poor condition, for bridge elements.  However, our goal is not only based on numbers but also on a case by case evaluation. Let’s say that we have an abutment that is in a condition state 4. It does not mean that the abutment is unsafe. It just means that the abutment is not in a good condition. It may have been in that condition for 20 years and it may be able to provide another 10-15 years of service life in that condition. Sometimes it is necessary to be aggressive on a bridge element, sometimes not.  What is important is to evaluate the impact of the element on the functionality and the safety of the bridge.

Can I say that that you are in favor of a selective approach?
If you just look at numbers, they are pretty sterile; they do not tell you the whole story. It takes skilled, talented, knowledgeable professionals within each State Agency to evaluate risks related to the condition state of bridge elements. To be able to quantify and qualify these risks is a key knowledge that ultimately keeps public safe.

You do not want to spend funds just to make the numbers look good.  You want to do the right thing for your bridge inventory.  If you can postpone expenditure for 15 years without jeopardizing safety and function, then this is the right thing to do in my opinion.

Who takes decisions related to bridge elements at Maine DOT?
We take decisions in a bridge committee that comprises of three legs: bridge maintenance, bridge design and construction, the so called capital program, and bridge management. It is what we call Maine DOT’s bridge community.  We know each other. A lot of us have worked together for as long as 30 years.

I am also part of a posting committee at Maine DOT that takes decisions on bridge weight restrictions. If a bridge does not meet a certain level of capacity based on bridge ratings, we evaluate whether we post the bridge or we strengthen it. In some cases, we do research, such as load testing, cutting coupons out of the steel to see if it is still strong, or cutting reinforcement steel in concrete to see strength can be added.

Some posting can be restrictive thus impacting community and commerce.  Bridges in rural areas usually need fewer restrictions since they just carry fire trucks and light vehicles. Even though many bridges in Maine are in good condition, they were designed 60 years ago for a much lighter type of vehicles.  Over 50% of Maine bridge inventory is more than 50 years old.

We spoke of the challenge of making people aware of bridge preservation benefits. Are there other major challenges?
The availability of experienced, qualified workers is another major challenge for bridge preservation. Craft people are not readily available as they once were. This challenge is not peculiar to Maine but rather a nationwide issue.

Do you do in-house maintenance work?
Two years ago Maine DOT started contracting maintenance jobs out. We had more money for maintenance than in the past but not enough people to do the job. We therefore decided to contract out using those additional funds. It was a little clunky at first because we had never contracted jobs out before.  The capital department had always done all the contracting for bridges at Maine DOT. We had to learn how to put out contracts and they are small contracts, generally under $200,000.

With the increased funding, do you have enough money for all preservation work at Maine DOT?
In 2007 and 2014 we developed two reports called “Keeping our Bridges Safe” (see Linkage – Ed. Note). Those reports recognize the need of spending $140 M/year for bridge preservation. However we get on average $105 M/year. As a result of being we remain $30 – 40 M/year short of spending requirements, at Maine DOT we are accumulating a spending deficit of $90 – 120 M in the length of time of 3-4 years.

Is there any bridge preservation success story you would like to share?
I think our biggest success story is that the entire bridge community at Maine DOT is on board with bridge preservation and really sees the value of it.

Painting may not improve the NHS condition rating of a superstructure, sealing concrete may not improve the NHS condition rating of a substructure; however these are important actions to keep bridges in a good condition. As an analogy, regularly changing the engine oil does not modify the way one drives a car but it makes a big difference in the longevity of the cars’ engine.

Does TSP2 assist you in reaching your bridge preservation goals?
I remember when Ed Welch from New Hampshire DOT, Pete Weykamp from New York DOT and Everett Barnard, my predecessor at Maine DOT, used to meet in New Hampshire with maintenance personnel. These three people first recognized the need for bridge preservation to have its own forum. So my hat goes off to them for pushing the preservation idea and setting up the conditions for having the Partnerships.

To me every year TSP2 Bridge Preservation meetings are better. Communication between bridge preservation practitioners is improving and we have more proficient people representing manufacturers. I can call up a number of engineers that are part of the Partnership and ask: have you tried this? Have you got this problem? What do you do to solve it? The network is just phenomenal.

There is a great value for bridge preservation practitioners to connect with product manufacturers’ people at the TSP2 Bridge Preservation Partnership meetings. Bridge practitioners can speak with different manufacturers and compare their products. There is also an opportunity for competitors to confront their products. Manufactureres also have avenue where they can speak with each other and potentially start collaborations for putting together different products and technologies in order to solve bridge preservation problems. TSP2 sets the stage for creating synergies between product manufacturers.

LINKAGE

Maine DOT
http://maine.gov/mdot/

“Keeping Our Bridges Safe” 2007
http://www.maine.gov/mdot/publications/docs/plansreports/Keeping%20Our%20Bridges%20Safe.1107.pdf

“Keeping our Bridges Safe” 2014
http://digitalmaine.com/cgi/viewcontent.cgi?article=1083&context=mdot_docs

Judith Corley-Lay, Director of NCPP

Author: Lorella Angelini, Angelini Consulting Services, LLC

In April 2017 Judith Corley-Lay took the leadership of the National Center for Pavement Preservation team thus succeeding to Larry Galehouse after his retirement.  Judith comes to NCPP and TSP2 with an impressive track record.

She started her career teaching Civil Engineering at the University of Texas in Arlington focusing on geotechnical engineering, contactor specifications and engineering economics. After several years with the University of Texas, she joined Texas A&M (Agricultural and Military) where she thought for two years and was also appointed to the staff of the A&M Transportation Institute. When her husband took a position at the University of North Carolina, she relocated to North Carolina, where she started working in the pavement management unit at North Carolina DOT (NCDOT).  For 26 years, up until her retirement in September 2016, she developed an extensive knowledge of pavements, including design, data analysis, field data collection, and pavement management systems.

When Larry Galehouse left the National Center for Pavement Preservation (NCPP), she decided to step out of retirement and apply for his position. She is now employed by Michigan State University (MSU), working from North Carolina where her family lives.   When I asked her about the decision to apply for the position as Director of NCPP, she told that it came from the realization of the great value of the TSP2 Partnerships, her desire to continue their activity and contribute to their success. In her work at NCDOT she has had first-hand interaction with the South-East Pavement Preservation Partnership (SEPPP) that brought her a huge amount of benefit.

Can you speak of the challenges of continuing the job started by Larry Galehouse?

When you are taking over from somebody like Larry, who had led an organization from the beginning, it is a daunting task. While I know a lot about pavement preservation, I am putting a lot of emphasis on becoming knowledgeable in the areas of bridge preservation and equipment management. For this reason I made the commitment to attend every Partnership meeting for at least first year. This allows me to learn first-hand about how the different groups work.  

Michigan State asked me to increase the research activity for bridges, pavements and also equipment. In collaboration with John Hooks, who is an excellent writer and editor, we wrote a proposal for accelerated bridge preservation for Michigan DOT. The proposal was accepted. This, was really good because (NCPP) had not had any research for Michigan DOT in several years.

One of the complications of my job is that you really have to balance the activities the Partnership focuses on with the activities from the University and the Oversight Panel. These activities are not always coincident.

What can you tell about the activity from the Oversight Panel?

The Oversight Panel is chaired by George Conner from Mississippi DOT, who is also the chair of SCOM, Sub-committee on Maintenance. The Oversight Panel represents AASHTO in overseeing the TSP2 program by NCPP. We answer to AASHTO that legitimately wants to know how expenditures into the program are being used.

During the last session the TSP2 Committee came up with the idea of funding small research projects with the Partnerships. While half of TSP2 excess balance is used for future operations, TSP2 wants to spend the other half on operations related to activities through the Partnerships. We are going to ask the Partnerships to submit research ideas. Then a few of these ideas will be chosen and funded to the level of contribution already submitted by the States.

Excess fund comes from the States’ voluntary contributions to TSP2. These contributions fund two people to come to the regional Partnership meetings for both pavement and bridge preservation. A little carries forward every year thus building up an excess fund that we want to spend down doing research for the Partnerships.

NCPP is a Center at MSU. I have an appointment to the faculty of MSU even though I do not teach. NCPP is under contract with AASHTO to manage the TSP2 program, which includes all of the Partnerships for both pavement and bridge preservation. That is how everything is linked. One of the reasons NCPP was chosen by AASHTO is its ability to develop good relationships between the vending community and the Agencies.

TSP2 has indeed created a strong dialogue between state DOTs and vendors that was almost unthinkable some time ago. Could you comment about it?

TSP2 has been successful and innovative in establishing a relationship between Agencies and vendors, such as manufacturers, contractors and consultants.

Partnership meetings are set up with specific guidelines about the conversation cannot be about any project up for bid. This fundamental rule makes it possible for State agencies to talk with the vending community and have a really good conversation. You hear people talking: “What about this type of application?” or “I tried this, I had this problem, what do you suggest?” These conversations could not take place if they were related to contract projects.

Going back to your TSP2 appointment, could you provide some details about what your job responsibility entails?

I am focusing on three areas. One is overseeing the day by day operations, making sure that routine operations run smoothly. Another area concerns the development research programs, as I explained before. The third focus area, which is very important for me, entails increasing the activity with local Agencies, such as Counties, Municipalities, and Cities.

I recently spoke at the American Public Works Association (APWA) for the North Carolina chapter and at the asset management conference through the Michigan Local Technical Association Program (LTAP) in order to promote the concept of preservation and increase contacts between TSP2 and local Agencies.  

It is important to promote the preservation message. We should underscore the advantages that preservation brings to the community starting from tax dollars savings, especially in the long-term.

Spreading the preservation message also keeps the new leadership at state and local Agencies informed and knowledgeable about preservation. Agencies turn over leaderships every 4 years on average, which means that they are always in a training mode at some level.

What is your vision for bridge preservation?

Agencies must move beyond the Structurally Deficient (SD) bridge concept as they define their plan of action. If Agencies only focus on repairing or replacing SD bridges, there will likely be a huge wave of bridges moving from fair conditions to SD in the near future.  

Unfortunately, the MAP-21 legislation retained and amplified the focus of DOT Agencies on SD bridges since FHWA took SD as the measure for bridge performance in MAP 21 legislation. Definitively, focusing investments solely on SD bridges is not a sound strategy.

I think that focusing on SD bridges also leads the bridge preservation conversation in the wrong direction.

We have a great talent pool in the bridge preservation area. Practitioners are knowledgeable and passionate about their work. They know their inventory and they understand what it takes to keep the inventory working but we cannot give them value as long as SD remains the key topic.

Could you point out key challenges for bridge preservation?

As I said before, MAP 21 and its focus on SD bridges is a challenge. Another significant challenge entails the very large number of retirements that are happening at the state Agencies. Gap in experience is developing not just in the Agencies but also in the contractor community.

After the completion of the Interstate highway expansion in the 90’s, for approximately a 15-year period there was not much hiring. When people in their 60’s with 30 years of experience are now retiring, we replace them with people who have only 15 years of experience. There is a 15-years gap, which is huge in bridge preservation because preservation requires experience. Its knowledge is based on seeing problems and trying solutions. In spite of knowledge sharing at the Partnerships, it is only after a decision is played out in practice that one can know if it was correct or no.

This is not a reflection on the younger generation that is sharp and bright. I have a lot of faith in the younger generation given they have the time to develop some expertise. I am confident they will be able to move the bridge preservation issue to another level.  

What gives you the most satisfaction in your work?

There are two aspects of my work that I find most satisfactory. One is coming to the regional Partnerships meetings and hearing bridge practitioners being so honest about strengths and weaknesses of their program. They are inspiring with their honesty. The other aspect is of course the staff at the NCPP, who are wonderful people I enjoy working with. I respect their level of commitment. They really want everything to be perfect, which makes my job a joy.

LINKAGE:

APWA North Carolina Chapter
http://northcarolina.apwa.net/

Michigan LTAP 
https://michiganltap.org/

Kevin Irving with AZZ Metal Coatings

Author: Lorella Angelini, Angelini Consulting Services, LLC

Steel corrosion tops the list of bridge preservation problems. It shortens the service life of bridges and can pose a safety issue. Once corrosion has started, it is very difficult, almost impossible, to stop it. In the US 40% of carbon steel is used to replace corroded steel at a cost of $425 B corresponding to approx. 2.5% of the GDP. This cost does take into consideration the additional cost related to suspending or limiting the use of steel damaged infrastructures.

Galvanized steel is being increasingly adopted by DOTs as a mean to protect structural steel from corrosion. To know more about this growing technology I spoke with Kevin Irving, National Marketing Specialist with AZZ Metal Coatings.

Kevin, who is based in the Chicago area, has more than 25 years of experience in the Hot-Dip Galvanizing (HDG) industry. He has many qualifications, such as being a certified coating inspector by the NACE International and a certified presenter of the American Galvanizers Association (AGA). He currently serves as a National Board Member for the Chemical Coaters Association International (CCAI) and as a member of the TRB Bridge Preservation Committee. He is industry director for the Western and Midwest TSP2 Bridge Preservation Partnerships.

What are the benefits of HDG for bridge preservation?

HDG increases bridge safety while reducing maintenance costs. It consists of applying a protective zinc coating to steel thereby preventing rusting and deterioration of the steel. Since zinc corrodes up to 30 times slower than steel, galvanizing dramatically reduces steel corrosion. Zinc adheres to steel through the metallurgical bond provided by HDG.

What are major differences between galvanizing and other technologies for steel protection, such as metalizing and painting?

Galvanizing, metalizing and zinc-rich paints all provide barrier protection to the underlying steel. What separates galvanizing from the other two technologies is the fact that galvanizing provides a metallurgical bond between zinc and steel, creating three zinc-iron alloy layers and a nearly pure zinc outer layer. Instead, metalizing and paints provide a mechanical, not a metallurgical bond, between coating and steel. The mechanical bond is generally considered as a less performing bond when compared to the metallurgical.

All three technologies provide cathodic protection to the underlying steel although some types of zinc-rich paint provide less protection than others. If the coating gets scratched thereby exposing the steel, the zinc will preferentially corrode to protect the exposed area. HDG has the advantage of preventing scratches in the first place. In fact, the zinc-iron alloy layers created during galvanizing are harder than the base steel, making HDG much more abrasion resistant than other coatings.

Can HDG be considered an innovative technology?

HDG is a very good technology with an exceptional track record but it cannot be considered as an innovative technology. Some applications like the I-69 bridge northbound lanes near Indianapolis, the Stearns Bayou Bridge in Grand Haven, Michigan and the Ford County Bridge in Illinois were completed almost 50 years ago.  These three bridges represent a success story since no maintenance has been needed to date and another 30 years of service life should be expected for all of them.

Continuous-Galvanized Rebar (CGR) per ASTM A1094 produces a galvanized rebar with a pure zinc alloy coating structure.  Although the continuous galvanizing process has been used for decades on galvanized automotive steel, its application to rebar is new. The CGR process allows long lengths of rebar sizes to be stored for fabrication and then formed without cracking, peeling or flaking, and without requiring special equipment for forming.

The CGR coating passivates faster and corrodes at a slower rate than traditional HDG coatings. The CGR process is automated and faster, resulting in quicker lead times, repeatable quality and consistency in the coating.

CGR can also be dual-coated with epoxy to produce a duplex coating according to ASTM A1055 specification.  The additional epoxy barrier over CGR provides an affordable belt and suspenders approach for most extreme environments.

Is galvanizing an expensive technology?

According to Philip G. Rahrig, executive director for the AGA, the cost for HDG is approximately $1.76 per square foot. This cost should be slightly less for large tonnage jobs.

What are the fields of application of galvanizing technology?

The technology is widely used for steel structural elements, such as beams and rebars in reinforced concrete. It is also used for guard rails, street signs and posts.

Could you briefly describe the galvanizing plant process for a steel beam, for example?

In the HDG process, the steel beam comes to the galvanizing plant after being manufactured and prior to service. The first step of the process entails an inspection to check that no paint, mill markings and heavy grease are present on the steel surface. After the inspection the beam goes to a caustic degreasing bath to remove any grease, grime, oil, or dirt. Once rinsed in a water bath, the beam is immersed in an acid tank or pickling bath so as to remove of any mill scale or rust oxide. This is also followed by water rinsing.

After cleaning, the steel beam is immersed in a flux tank. The flux is a combination of zinc, ammonium and chloride. At 160 degrees Fahrenheit, the flux bath deposits a light coating on the steel, which keeps it from oxidizing. The flux bath also preheats the steel.  In the next and final step of the process the beam is submerged in a galvanizing kettle. This bath must have a minimum of 98-percent pure zinc to meet ASTM A123 requirements.

The galvanizing kettle is heated to a temperature ranging from 830 to 840 degrees Fahrenheit, at which point the zinc is in a liquid state. The steel beam remains in the zinc bath until the steel reaches the bath temperature. When the beam comes out from the kettle, the zinc coating must have a minimum thickness of 3.9 mils for steel more than 1/4-inch thick (ASTM A123).

It usually takes approximately three hours to complete the process from beginning to end. The steel is typically immersed in the molten zinc in the galvanizing kettle for less than 10 minutes. There are currently more than 75 plants in the United States that can provide galvanizing for steel elements for bridge construction.

What are the challenges in the HDG process and the steps to ensure it is properly done?

It is extremely important to check placement and number of vent and drain holes prior to the galvanizing bath. This ensures safety during immersion of the steel in the molten zinc by allowing pressure to escape from air and moisture present in internal sections of fabrications. It also allows the molten zinc to contact and form the HDG coating on all internal and external surfaces. Vent and drain hole requirements are outlined in ASTM A385.

It is also preferred that the piece is completely fabricated before being galvanized so as to avoid welding after the galvanizing process.  If welding is needed after HDG, the zinc must be burnt off with a torch or ground off until there are sparks in order to be sure that the steel substrate is reached.  Upon completion of welding, it is necessary to restore corrosion protection on the area where the galvanizing was removed and on the weld.

It is good practice to communicate with the galvanizer prior to design and fabrication. This provides the best opportunity to address design details that could affect the formation of the HDG coating.

Can you share a case study?

The Stearns Bayou Bridge in Grand Haven, Michigan, was galvanized and installed in 1966. The steel is in very good conditions without having required any maintenance from the time of construction.

This county bridge is 430 feet long with a 30-foot clear roadway and a 5-foot walkway along each side. The majority of the steelwork is 6 feet above a freshwater river in a rural location. The bridge experiences light to moderate traffic and the entire bridge is subject to winter salting.

After 51 years following the construction, all the beams and diagrams are in very good shape showing no signs of rusting or staining despite the fact that the bridge is subjected to snow and deicing salts. The average zinc coating thickness is 5.4 mils, which indicates that HDG will continue to provide corrosion protection for decades in this environment. All bolted connections also show no signs of rust.

However, in five places on the tubular rails on the top of the bridge there are signs that the zinc has been completely consumed thus exposing the metal substrate. The preservation process for these areas simply requires applying a zinc rich paint over the exposed steel.  The rest of the rails should be power washed with some type of salt mediation and painted over without sandblasting on a completely dry surface. Standard specifications (ASTM D6386 and SSPC Guide 19) must be used as guidance for the paint application.

LINKAGE

AZZ Metal Coatings https://www.azz.com/metalcoatings

You Tube video from AGA: “Hot-Dip Galvanizing: Protecting Steel For Generations” https://www.youtube.com/watch?v=kwCyq06aatA

You Tube video from GalvanizersAssocAus: “Hot Dip Galvanized Steel – What, How & Where” https://www.youtube.com/watch?v=c2J07n5hSbs

You Tube video: “AZZ Galvanizing Overview”
https://www.youtube.com/watch?v=CNukOte3tSU

You Tube video: “AZZ Galvanizing Workflow”
https://www.youtube.com/watch?v=YVWgGYGEer4

Jeffrey Milton with VDOT

Author: Lorella Angelini, Angelini Consulting Services, LLC

Jeffrey Milton, Bridge Preservation Specialist with Virginia DOT (VDOT), is a bridge preservation leader in his State and at national level.

Jeffrey is member of the AASHTO Subcommittee on Maintenance chairing the Technical Working Group on Bridges. He is also part of the FHWA Bridge Preservation Expert Task Group and actively involved with TRB and NCHRP, where is covers a number of Committee Memberships.

• TRB Standing Committee on Structures Maintenance – AHD30 Member
• TRB Standing Committee on Bridge Preservation – AHD37  Member
• NCHRP Project Panel on Development of Guidelines for Uniform Service Life Design for Bridges D12108  Chair
• NCHRP Project Panel on Condition Assessment of Bridge Post-Tensioning and Stay Cable Systems Using NDE Methods D1428  Member
• NCHRP Project Panel for Extending the Life of Highway Bridge Coating Systems Through the Use of Spot Painting with Minimal Surface Preparation D1430  Member

Jeffrey is a member of the FHWA Technical Panel for update of NHI Bridge Maintenance Training Course and development of NHI web-based Bridge Preservation Training Course. He is also member of the TSP2 oversite panel.

I recently had the opportunity to speak with Jeffrey about VDOT bridge preservation program.

How does bridge preservation fare at VDOT?

Using Virginia structure data as of September 1, 2017, the total number of structures in Virginia inventory sums up to 21,124, of which 13,113 bridges and 8,010 culverts. Out of these structures, 19,469 entail VDOT owned/maintained structures, of which 11,910 bridges and 7,559 culverts. The number of city, county and town owned/maintained structures is 1,463, including 1,044 bridges and 419 Culverts

VDOT defines Condition Categories for structures as Good, Fair and Poor.

• Good Condition means a low General Condition Rating of 6 or greater
• Fair Condition: a low General Condition Rating equal to 5
• Poor Condition: a low General Condition Rating of 4 or less

Condition Categories for the 19,469 VDOT Owned/Maintained structures currently report a limited number of structures in Poor Condition.

• 13,891 (71.3%) of the structures are in Good condition
• 4,818 (24.7%) of the structure are in Fair condition
• 760 (3.9%) of the structures are in Poor condition

What does bridge preservation entail at your DOT?

At VDOT bridge preservation is part of a comprehensive Bridge Program that includes preventive and restorative maintenance, painting, rehabilitation and replacement.

Examples of preventive maintenance are bridge cleaning, deck sealing, sealing joints, thin deck overlays and spot and zone painting.

Restorative maintenance includes deck patching, rigid deck overlays, reconstructing/closing joints, superstructure repairs, substructure repairs, fatigue retrofitting, scour repairs, cathodic protection and electrochemical chloride extraction.

Painting encompasses spot and zone painting, over-coating, complete removal and repainting.

Superstructure replacements, deck replacements and culvert rehabilitation are examples of rehabilitation. Rehabilitation and replacement are not part of VDOT Bridge Preservation Program, which focuses exclusively on preventative maintenance, restorative maintenance and painting.

What criterion does VDOT use to determine actions that should be implemented?

Our criterion can be outlined in three points.

• Preventive maintenance candidates are structures in Good Condition (a low General Condition Rating of 6 or greater)
• Restorative maintenance candidates are structures in Fair Condition (a low General Condition Rating equal to 5)
• Rehabilitation and replacement candidates are structures in Poor Condition (a low General Condition Rating of 4 or less).

We also use element level condition states and defects to develop specific maintenance and preservation treatment options.  We previously used AASHTO Pontis for our bridge Management system, and we are now investigating the use of AASHTO BrM.

As a general guideline, we want to make sure that preventive, painting, and restorative works are performed before the onset of serious deterioration while the structures are still in good or fair conditions.

We adopted a breakdown for the allocation of bridge structure funds that foresees 15% for preventive maintenance, 10% for painting, 25% for restorative maintenance and 50% for rehabilitation / small structure replacement. This balanced breakdown helps select efficient and effective actions, as it is essential in order to maintain a healthy bridge structure inventory.

Can you outline key bridge preservation strategies at VDOT?

Some VDOT structure/bridge preservation strategies include:

• Eliminate deck expansion joints. The designer must evaluate the feasibility of joint elimination. When elimination is not possible, the designer will have to submit justification, including supporting calculations, to the Assistant State Structure and Bridge Engineer for Maintenance.
• Reconstruct concrete adjacent to joints and install strip seals. When joints cannot be practically eliminated, specific activities should be performed such as perform concrete substructure surface repair and apply waterproofing coating/treatment to pier and abutment seats and ends of beams/girders.
• Install asphalt plug joints with back-up sealers on decks having asphalt overlays.
• Prepare concrete decks using hydro demolition and place rigid concrete overlays.
• Coat beam ends and substructure caps under joints.

What challenges have VDOT encountered in the implementation of bridge preservation strategies?

Like many Agencies, our corporate culture has previously taken a worst first approach to the bridge program, with major emphasis on structurally deficient structures.  We have made great progress with our management in promoting a preservation approach focusing on preventive, painting, and restorative works for extending the service life of our inventory.

Can you inform of new technologies that have been recently adopted by VDOT?

We have started using hydro demolition and placement of rigid concrete overlays to protect the concrete deck. We are also investigating the use of hydro-demolition and hydro-milling for concrete removal on substructures.

VDOT Structure and Bridge Division and the Virginia Transportation Research Council are investigating the use of remotely operated data gathering devices and remotely operated maintenance devices. These devices, which include Microsoft HoloLens, unmanned aerial vehicles (drones) and crawling devices designed for bridges and culverts, can be outfitted with various sensing technologies, such as infrared, high resolution cameras and impact (sound).

We are in the process of conducting a research project in order to investigate the use robotic devices in conjunction with lasers for the removal of paint from steel beams and girders.

How can TSP2 help VDOT reach its goals?

TSP2 provides a very valuable platform for sharing information of treatment methods, best practices and research projects among the States, especially when participating in regional and national working groups.  The TSP2 staff provides support to the preservation program in Virginia and throughout the nation.

LINKAGE

Chapter 32 of the VDOT Manual of the Structure and Bridge Division (File 32.01-9-12) shows the VDOT Bridge Planned Preventive Maintenance Program.  A link to this document follows: http://www.virginiadot.org/business/resources/bridge/Manuals/Part2/Chapter32.pdf

VDOT is in the process of reviewing and updating this document (Ed Note).

A link to the FHWA Bridge Preservation Guide follows: https://www.fhwa.dot.gov/bridge/preservation/guide/guide.pdf

This guide will be updated by the FHWA Bridge Preservation Expert Task Group (Ed Note).

David Miller with LaDOTD

Author: Lorella Angelini, Angelini Consulting Services, LLC

About one year ago, David Miller was promoted to the Chief Maintenance Engineer position at the Louisiana DOTD (LaDOTD). Before that he served for several years as the Bridge Maintenance Engineer for the State. David is happy his new position gives him the opportunity to remain involved with the bridge program and he can take preservation issues further. 

As Chief Maintenance Engineer David Millers’ responsibilities include managing the ferry systems, signs and signals, bridge inspection, loss prevention and truck permits.  He is also in charge of the statewide bridge crews that work on complex preservation projects and the statewide crews that specialize in putting up signals and sign trusses. On the other hand, the crews that carry out the day-to-day work for the maintenance of bridge and road assets are managed by the nine LaDOTD Districts

Some of the longest bridges in the United States are located in Louisiana. With 175,000,000 square foot of deck area (2016 FHWA data), Louisiana ranks as the fourth largest state for bridge deck area. It follows Texas, California and Florida, which all have a higher number of bridges than Louisiana. In addition to having long bridges that span over the Mississippi and across marshlands, Louisiana has also a large number of timber bridges (third most in the US), which were built years ago during the expansion of local timber industry.

What does bridge preservation entail at LaDOTD?

Bridge preservation can be divided in two parts in Louisiana. One part entails larger preservation projects that are managed through the bridge preservation program that has been in place for about 10 years. It is part of the overall bridge replacement, bridge rehabilitation capital program and allocates from $30 to $40 M per year specifically for bridge preservation projects. Projects are selected through a committee that takes input from the districts and are back checked with deterioration models from Pontis in the past, AASHTO BrIM currently.  This part is where the heavy lifting on the preservation side comes in.

The other part is funded through the operating side of the budget. This entails maintenance and preservation activities that are done by districts’ bridge crews and statewide crews. Unfortunately, our crews tend to do more emergency-related work than preventative maintenance because many bridges in Louisiana are in poor condition. (In 2016, LaDOTD reported 1,739 structural deficient bridges, corresponding to 13.5% of 12,915 total number bridges. Ed. Note). Our crews also focus on preserving our timber bridges to keep them open and safe.

What is your bridge preservation strategy?

Our strategy at LaDOTD is to improve the condition of bridges and their ratings every time it is possible. For example, if a paint project is scheduled for a particular bridge, we do not necessarily want to do the painting only. We evaluate whether there is a structural rehabilitation project that can be done in parallel to painting to improve the overall rating of the bridge. A pure painting project does not move the rating of a bridge from poor to good.

The majority of our preservation activities have been focused on bridges that are in poor conditions. Our goal is to bring these bridges from poor to fair or from poor to good. Mainly because of lack of funds, we are not at the point that we can do activities on bridges that are in good condition, which is the recommended preservation approach.

Our gas tax, 16 cents per gallon, was implemented in the 80s and has not changed, or been indexed, since then.  We recently went through an effort with our Legislators to try to increase the tax in order to have more funds to maintain bridge and road assets. Unfortunately, this effort failed to pass. This will make our responsibilities in maintenance difficult to carry out as we continue to deal with our relatively large number of posted and structurally deficient bridges. It will take additional funds to be able to get ahead of the curve and do more of strategic preservation activities on our bridges.

Four of the top five longest bridges in the United States are in Louisiana. Most of these bridges belong to the interstate system and are in good shape. However, having to deal with long bridges puts an additional strain on our resources.  Preserving a bridge that is 20-miles long and has a twin structure requires a lot of money. A tremendous amount of money is required just to tackle one element of the bridge, for instance the deck.

What is the LaDOTD strategy with structurally deficient bridges?

We have prioritized work on structurally deficient and posted bridges that are on the major truck routes.

We are also planning to replace all our timber bridges.  This poses a challenge as we have the third most timber bridges in the country.  Most of these bridges, which were built in the 50’s and 60’s, are deteriorated beyond their service life.

What are the challenges in the implementation of your preservation strategy?

As I said before, the biggest challenge for us is funding. Our administration understands the need for additional funding for highway infrastructure, so hopefully there will be additional funding in the future.

Do you have a success story you would like to share?

Probably the biggest success story is just the fact that LaDOTD has a bridge preservation program that has been in place for 10 years. There have been some major projects completed through this program. One of these was the rehabilitation of Huey P. Long – O.K. Allen Bridge crossing the Mississippi in Baton Rouge. This is a steel truss bridge over a mile long. It is a both a railroad and highway bridge, the only bridge of this kind owned by the state.  It was brought to fair condition through a rehab project that entailed structural repairs with member strengthening and painting. It was a typical preservation-style project even though it was necessary to use more than the normal preservation funds.

Is TSP2 helping LaDOTD reach your goals? And how?

TSP2 provides a very valuable forum for networking with peers from other states and federal agencies. During the annual South-East Bridge Preservation Partnership (SEBPP) meeting, we get the opportunity share knowledge, success stories and failures. We can learn from states that are ahead in certain areas of bridge preservation. We can also learn their preservation strategies and how they were successful in getting funding increases for their department. TSP2 is definitively a big plus for us.

I would suggest improving the liaison between TSP2 and the Sub-Committee on Maintenance (SCOM), specifically in relation to the flow of research projects. We streamlined this process at SCOM about two years ago (David is Vice Chair on the SCOM Bridge TWG for Asset Management, Performance Measures and Environment. Ed. Note) and now it is TSP2 that is addressing this process. There is the need for fine-tuning research needs between SCOM and TSP2.  There is definitively room for improvement in this aspect of the collaboration.

TSP2 is now sending representatives from its four regions to SCOM. This really helps with creating continuity between SCOM and TSP2.  For example, at SCOM we recently learned from the North-West TSP2 Region about the benefits of bridge washing and how to get through the process with environmental groups.  That would have never happened had the North-West Bridge Preservation Partnership (NWBPP) not sent representatives to SCOM.

In general, the more time SCOM and TSP2 people meet and have discussions the better they will be able to get on the same page.  Flow of information between SCOM and TSP2 is improving, but it could get better.

LINKAGE

Bridge Preventive Maintenance Program:

http://wwwsp.dotd.la.gov/Inside_LaDOTD/Divisions/Engineering/Bridge_Design/Pages/Preventive_Maintenance.aspx