A Conversation with Rod Thornton of MDOT – SHA

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.



NCHRP Project 20 68A, Scan 15-03

Successful Preservation Practices For Steel Bridge Coatings



SHA Paved Invert Specifications


A Conversation with Ed Welch with TSP2

Ed Welch with TSP2

Author: Lorella Angelini, Angelini Consulting Services, LLC

Ed Welch is the leading preservation engineer supporting the TSP2 bridge program at the National Center for Pavement Preservation (NCPP).  It is safe to say that his level of competence and the passion he has for his job are unmatchable.

Ed is active with the four Regional Bridge Preservation Partnerships, a task that also includes organizing and implementing the yearly TSP2 Regional Bridge Preservation Partnership Meetings as well as the National Conference that takes place every four years.  He participates in many National and Regional TSP2 Working Groups, and the monthly regional teleconferences.

Ed Welch evaluates and supports new initiatives and programs, always making available his knowledge and experience. Even more important, Ed facilitates communication, thus making it possible to create a multi-faceted dialogue between States, Agencies, Industry and Consultants. This dialogue is at the core of the TSP2 Bridge Preservation success story.

I spoke with Ed after the TSP2 National Conference in Orlando, Florida.

Could you introduce yourself? What is your background? Why did you decide to join TSP2? How did it happen?

I am a bridge preservation engineer at NCPP, the National Center for Pavement Preservation at Michigan State University that has a contract with AASHTO for managing TSP2 for both bridges and pavements.

After getting a Bachelor of Science in Civil Engineering from the New England College, I spent four years with HNT&B and then thirty-four years with the New Hampshire DOT.  Nine of those years were with bridge construction and twenty-five with bridge maintenance.

Back then I attended the Sub-Committee of Maintenance (SCOM). As the Bridge Maintenance Engineer for New Hampshire I was able to attend meetings in Alaska, Alabama, Pennsylvania, Minnesota, North, Dakota, Washington State, and New Hampshire, where we all learned about the value of networking and developing relationships from around the country. Wade Casey with FHWA, one of the relationships that I developed at the SCOM Meetings, recommended me to Larry Galehouse, NCPP Director, as a potential candidate for the new TSP2 bridge preservation position. The rest is basically history.

I have been supporting the TSP2 bridge preservation program for about eight years. It is a great experience. I have learned a lot from the continuous exchange of knowledge and bridge preservation experience between the States, and how eager all members of the Partnerships are to share and to learn. I am getting to know bridge preservation and asset management practitioners from States, Industry, and Academia from the entire country. It is very rewarding for me to get them together on the phone, on the computer, or face to face.

The National TSP2 Bridge Preservation Conference took place recently in Orlando. This is a pivotal meeting that occurs every four years. Was the Conference successful? Did TSP2 reach its goals? Is there anything that fell below expectations?

The 2018 National Conference was a very successful meeting. We had over six hundred attendees, more than sixty exhibiting companies, of which thirty-one took part in the outdoor demonstration.

Florida DOT was an exceptional hosting partner who truly supported the Conference. They sent forty-one attendees who did a lot of work behind the scenes focusing on IT and the outdoor demonstrations.

Eighty different presentations were made in three separate sessions. (Note: See Related Links for the presentations’ videos at the bottom of the post).  All the independent Committees reached the common goal of making the 2018 Conference a great meeting. They should be praised for the excellent job they did.

A questionnaire that was sent to all attendees at the end of the Conference received very positive feedback

What could we have done differently? For the first time we had an App for getting information about the Conference and facilitating networking. It made it easy to anticipate the Agenda and take early decisions about which of the three concurrently running sessions to attend. The App was received very well to the point that I think we should have promoted it sooner.

How was the 2018 TSP2 National Bridge Preservation Conference different from the 2014 Conference that also took place in Orlando? What changed in these four years?

Compared to 2014, in 2018 we had much more interaction between the four Partnerships as well as between the States and Industry.

During the Working Group sessions, representatives from each Partnership were able to discuss what is being done, and also to open these discussions with other Partnerships and Industry representatives.  Key accomplishments reached by both the Regional and National Working Groups were shared among all participants.

At the 2018 Conference we also took the opportunity to highlight key presentations that were made over the last three years at the Regional Partnership meetings. Each of the Partnerships wanted to bring in these presentations so as to share them at national level. The four presentations were:

  • “MnDOT Bridge Maintenance Training for State and Local Agencies” by Sarah Sondag with Minnesota DOT (MWBPP);
  • “It’s Flooding Down in Texas – Lessons Learned from Seven Mass Flood Events” by Graham Bettis with Texas DOT (SEBPP);
  • “Preservation of Bridge Retaining Walls” by Ben Foster with Maine DOT (NEBPP);
  • “A Preservation Contractor’s Perspective: The Good and the Bad” by Kurt Clink with Truesdell Corporation (WBPP).

Is TSP2 planning to organize a third National Bridge Preservation Conference in 2022? Is TSP2 considering shortening the time between the National Conference meetings from four to two? Will the four Regional TSP2 Bridge Preservation Meetings remain in place in 2019, 2020 and 2021?

The next National Bridge Preservation Conference will take place in 2022.  We are looking for a host State, who can perform as well as Florida did for the two Conferences in 2014 and 2018.

We are not going to shorten the time between the National Conferences from four to two years because we want to have continuity at a regional level and make sure that the Regional Partnerships maintain a bridge preservation perspective. As an example, representatives from the Midwest Bridge Preservation Partnership who participated in the National Conference in Orlando in April 2018, will not meet again until October 2019, when the Regional Partnership Meeting is scheduled to take place in Bismarck, North Dakota. A year and a half between the two gatherings is quite a long time for the Midwestern bridge preservation representatives.

We want to have the Regional Partnership meetings on a regular basis since they are so valuable and popular.  We will therefore continue to have a Regional Meeting for each Partnership every year for three years in a row before organizing the National Conference.  This scheme has worked well so far for both the pavement and the bridge side.

Could you outline key programs for TSP2 Bridge Preservation, beyond organizing the Regional Partnership Meetings and the National Conferences?

The ongoing work of the Regional and National Working Groups is a crucial element of the TSP2 Bridge Preservation program.

National Working Groups address issues that are important to the four Regional Partnerships, who should always have a representative participating in the Groups. In most cases the National Working Groups have been created because a particular topic was already discussed at several of the Regional Working Groups. This happened, as an example, with the National Coating Working Group. There were already Working Groups focusing on coatings in the Regions, so it made sense to combine these Working Groups and generate a national effort.

We currently have five National Working Groups. These are the “Bridge Management System (BMS)”, the “Industry Technology Demonstration (ITD) Program”, the “Social Media Program”, the “Bridge Deck Preservation” and  the “Bridge Preservation Coatings” that I have just mentioned.

Additional National Working Groups have been proposed and are being considered.

As far as Regional Working Groups, the Midwest Partnership has four groups: “Outreach to Local Agencies”; “Systematic Preventive Maintenance (SPM)”; “Preservation Matrix” and “Deterioration Modeling”.

There are four Regional Working Groups in the Northeast Partnership: “Scour Working Group”; “Beam End Treatments”; “Bridge Washing” and “Research”.

The South-East Partnership has three Regional Working Groups: “Bridge Preservation Performance Measures”, Website Development and “Structural Health Monitoring”

There are four Working Groups in the Western Partnership: “Bridge Preservation Activities Matrix”, the “Quantifying a Systematic Preventive Maintenance Program”; “Research” and “Asset Management”.

As I said before, when the Regional Working Groups develop and find commonalities, they can evolve into National Working Groups.

A crucial part of the TSP2 Bridge Preservation program also entails promoting bridge preservation awareness to Local Agencies across the nation, such as Cities, Towns, and Counties. There is a lot going on as far as Local Agencies getting involved in bridge preservation. This should be of no surprise since Local Agencies own more than 50% of the bridges in the nation. It is therefore essential that Local Agencies be trained to properly maintain and preserve their bridges.

Three different initiatives have currently been put in place in order to improve Local Agencies’ involvement with bridge preservation policies and practices. The first entails the creation of a discussion group that focuses on networking with the objective to promote calls and meetings between States and Local Agencies. The second initiative involves the Western Regional Partnership that has established a Working Group about communicating the value of bridge preservation (Note: See Related Links about this Working Group at the bottom of the post). The Working Group is putting together modules for short presentations at Local Agencies and is looking for volunteers. The third initiative consists in the TSP2 Bridge Preservation training for Local Agencies that has been developed at NCPP. If a State is interested in gathering Local Agencies, NCPP@MSU can do half or full day bridge preservation training for them. We have an “a la carte” agenda where States and Local Agencies can pick and choose what they want to hear depending on their needs and capabilities.

It is likely that a National Working Group will be soon established about promoting bridge preservation to Local Agencies. FHWA has also an initiative in place focusing on Local Agencies to promote the value of bridge preservation.

All initiatives related to Local Agencies cannot use State’s funds contributed to the AASHTO TSP2 Program. While we must be careful regarding the extent of funding for these initiatives, there are remedial needs that the Partnerships can assist Local Agencies with.

Seasoned bridge preservation engineers, Pete Weykamp, retired from NYSDOT and John Buxton, retired from Maine DOT, are NCPP trainers. Since I have done some training myself, we currently have three bridge preservation engineers who can do the training for Local Agencies. We have already carried out training in several States and we are seeing more and more interest toward such training.

What is your vision for TSP2 Bridge Preservation?

I envision that the concept of bridge preservation will be fully understood and embraced by our bridge preservation community, and, at a different level, by the public. For this reason, the social media program is very important for TSP2. We certainly have a lot of room for bridge preservation to expand and social media is an excellent avenue to follow.

A correctly implemented bridge preservation policy can have a significant financial impact on our nation. This is the core message promoted by TSP2. Bridge preservation frees financial resources since it is certainly more economical to work on bridges in good or fair condition rather than on deteriorated bridges. In other words, Bridge Preservation is good for the economy.

The life of a bridge can be extended with a minimum cost if the right preservation action is taken at the right time. By doing so, States can focus more funds and resources on those bridges that are beyond restoration and need to have major rehabs or to be replaced.

Keeping most of bridges in “fair” condition appears to be a good means of managing our bridge assets. It is evident that we cannot keep all the bridges in “good” condition. This is sometimes a tough concept to accept. However, it is the reality. To have all bridges in good condition and to get there by only replacing the worst bridges cannot be regarded as a sustainable goal.

As I explained before, I envision a constant, gradual growth in the adoption of bridge preservations policies by the Local Agencies.

I would also envision our TSP2 Bridge Preservation representatives reaching out to representatives from other countries, especially Canada.


Related Links

TSP2 – Bridges:


Videos of presentations at the 2018 Conference in Orlando:


Working Group about communicating the value of bridge preservation established by the Western Regional Partnership: