Keith Kesner

Author: Lorella Angelini, Angelini Consulting Services, LLC

I met Keith Kesner at a monthly educational meeting organized by the Minnesota Concrete Council (MCC) in St. Paul, MN, when he gave a very informative presentation about the American Concrete Institute (ACI) 562: “Code Requirements for Assessment, Repair, and Rehabilitation of Existing Concrete Structures and Commentary”. I then contacted Keith in order to know more about the new Code and its potential use for bridge preservation.

Keith, the chair of the ACI 562 Committee, is a registered Professional Engineer in several States. He has over 20 years of experience as a structural engineer and he has written over 100 publications on a variety of structural engineering topics. He works as a Project Manager with CVM Professional in King of Prussia, PA, a Consulting Engineering firm that specializes in the evaluation and rehabilitation of existing structures.

Founded in 1904 and headquartered in Farmington Hills, MI, ACI is a leading authority and worldwide resource for the development and distribution of standards, technical resources, educational training and certification programs related to concrete design and construction. ACI has over 95 chapters, 110 student chapters, and nearly 20,000 members spanning over 120 countries.

Could you speak of the goals of ACI and introduce the ACI 562 Concrete Repair Code that you chair?

ACI is an international organization with the objective of developing and distributing knowledge on concrete design and construction. Some of the key goals of the Institute include the development and maintenance of standards and consensus documents for the design, construction and repair of concrete structures.

People are probably most familiar with ACI 318 Building Code, which is the US Standard Code for reinforced concrete construction. ACI 318 is also very heavily used internationally.  ACI has produced a wide variety of other documents, such as specifications and procedures for concrete construction in different types of environment, from hot to cold weather, development and standards for the use of Fiber Reinforced Polymer (FRP) materials and the repair of concrete structures.

ACI has much wider reach than what people are most familiar with, which is ACI 318.  It is a very large organization that covers all aspects of concrete construction.

Who are the professionals that are part of the ACI membership? Does ACI mainly gather Consulting Engineers?

Consulting Engineers are a prominent presence in ACI, but other groups of professionals are also strongly represented in the Institute. These groups include cement producers, concrete producers, manufacturers of construction products, contractors focusing on concrete construction and repair, and academics involved with research on the design and construction of reinforced concrete structures. ACI has a very broad-based membership that touches all aspects of the concrete industry.

What are the key elements of the new ACI 562-16 Code?

The ACI 562 Code was developed to be a parallel document/Code to ACI 318. Whereas ACI 318 deals with new building construction, ACI 562 was developed specifically for the repair of existing concrete buildings. It was also designed to work with the International Existing Building Code (IEBC).

ACI 562 was designed to be a performance-based code with prescriptive requirements when required. It basically provides design professionals with code requirements for the assessment of existing concrete structures and then, depending upon the results of the assessment, procedures for the design of appropriate strategies for the repair, including durability requirements.  The code also calls for future maintenance and monitoring requirements to be documented by the licensed design professional for the owner.  However, ACI 562 cannot mandate that actual maintenance be performed.  

Is ACI 562 a new Code?

Yes, ACI 562 is a completely new Code. The first edition was published in 2013. The current ACI 562-16 edition, which was published last year, is an update of the 2013 version. So we are currently on the second version of the Code.

Is the 2016 update significant?

Yes, the Code was updated significantly from 2013.  We made a lot of changes to the terminology to make it consistent with documents published by other standard developing organizations. We added code requirements and commentary on these requirements to better define the level of repairs that may be required on existing structures. We worked on better integrating the Code with IEBC requirements.  We also spent a lot of time working on requirements for the bond of the repair material to the existing structure.

A major update entailed the introduction of the concept of “demand to capacity ratio” in order to better delineate the extent of the repair that may be required in a building.  As an example, let’s suppose that we have a beam with a load of 100 kips, as specified by the building Code. If after evaluation we find out that the capacity of the beam is, let’s say, 80 kips, we can calculate the demand to capacity ratio by dividing 100 by 80 = 1.25.  Being the ratio  greater than 1, the beam requires strengthening and the repair must be designed in order to provide the amount of strengthening that will bring the ratio back to or lower than 1.00.

In summary, the “demand to capacity ratio” represents a measure of how deficient the structural element is and therefore it is a measure of the amount of strengthening that needs to be added to the structural element in order to satisfy Code requirements.  

Does the Code include guidelines on how to evaluate the capacity of a concrete structural element that has deteriorated over time?

Yes, this information is contained in Chapter 6 of ACI 562, which deals with how to do the evaluation of a deteriorated structural concrete element. There are a lot of documents that have been published on the evaluation of existing concrete structures, which are referenced in the commentary to the Code. Design professionals using the Code can look up to these documents and can get additional information on how to evaluate the current capacity of existing concrete structures.

Where did the need for the new ACI 562 Code stem from?

The need was really recognized by people involved with the concrete repair industry, who realized that repairs on existing structures were not performing adequately. A thorough investigation was carried out by a couple of different groups: the US Army Corps of Engineers and the Building Research Establishment (BRE) in the UK. Both reports (see linkage, ed.) concluded that repairs of concrete structures were failing at a high rate. Improved repair techniques providing better performance of repairs were needed in order to avoid repair of previously repaired structures, which is obviously a waste of money.  

By creating a standard for the repair of building structures we responded to a recognized need in the concrete repair industry and made a significant progress in the direction of improving the performance of repaired concrete structures. In addition, by introducing the “demand to capacity ratio” concept, we provided a tool for achieving a consistent level of reliability for repaired concrete structures.

It is likely that what you said about repairing repaired structures also applies to the DOT experience with concrete repair. In fact DOTs have started focusing on preservation practices based on cyclical and preventative maintenance, which do not require major concrete repair applications.  How could ACI 562 be of help to bridge preservation practitioners?

The ACI 562 Code was specifically developed for building structures. A direct translation of many of its parts to bridges would not work since loads and resistance factors are different in bridges compared to buildings. However, the performance-based concepts that were used in the development of the ACI 562 Code can be appropriate for bridge structures.

Information included in Chapter 8 – Durability could be of particular benefit to bridge preservation practitioners. When we talk about durability of a repaired concrete structure we must consider the durability of the original structure, the durability of the repair, and the interaction between the repaired area and the original structure. This holistic approach to concrete repair underscores the fact that it is not sufficient to just have a durable repair or a durable portion of the original structure but it is the whole system that needs to work together.

A lot of the problems with durability of repairs relate to the addition of new materials, that have different electrochemical properties and stress-strain response than the existing materials. We must predict how these new repair materials are going to interact and respond when they are applied to the original structure. The comprehensive concrete repair concept will likely fit with current practices adopted within bridge preservation as part of an asset management program.

Would ACI consider the possibility to collaborate with TSP2 for the development of a performance-based specification for concrete repair?

Yes, absolutely. I would also suggest looking into ACI 365 Committee – Service Life Prediction, which is working on developing service life prediction standards and procedures for concrete structures. Some of the work that has been already done by the 365 Committee may be of great interest to engineers and practitioners who deal with bridge preservation.  

ACI Committee 563 is also in the process of developing specifications for repair of existing concrete structures.  The concrete repair specifications should be completed in late 2017 or early 2018.  

LINKAGE

ACI Vision 2020—Repair/Protection Council

http://www.concretesdc.org/projects/Vision_2020.htm

The Condition of Corps of Engineers Civil Works Concrete Structures, Technical Report REMR-CS-2, 1985, 133 pp.

Building Research Establishment (BRE): Thematic Network on Performance-based Rehabilitation of Reinforced Concrete Structures      

http://projects.bre.co.uk/conrepnet/pages/default.htm

ACI 562 from Structure Magazine

http://www.structuremag.org/?p=5454

LIFE-365 SERVICE LIFE PREDICTION MODEL

https://trid.trb.org/view.aspx?id=729747

Bill Oliva (WisDOT)

Author: Lorella Angelini, Angelini Consulting Services, LLC

Bill Oliva is a recognized leader in bridge preservation and asset management at both the national and State level. He is the Chief of Structural Development for Wisconsin DOT (WisDOT) and participates in the activity of the AASHTO Subcommittee on Bridges and Structures T-11 Research, TRB AFH40 Construction of Bridges and Structures and TRB Sub-committee on Accelerated Bridge Construction.

Could you talk about your responsibilities with WisDOT?

As the Chief of Structural Development for WisDOT Bureau of Structures, I oversee the development of policies, standards and automation. I am also in charge of bridge management and asset management, rating and permitting of bridges.

Previously with the Department I was bridge structural engineer, lead hydraulic engineer and I served for 10 years as a project development supervisor in our regional office. I was fortunate that I was given the opportunity to have a broad perspective on WisDOT activities and to relate them to the different business functions.

What does bridge preservation entail at WisDOT?

It entails many aspects from investment strategy to technology development with the common aim of building consistent expectations and goals that will apply to preservation of WisDOT infrastructures.

Building awareness about the challenges that we at the WisDOT face with maintaining the bridge inventory is a key element of bridge preservation. It essentially boils down to risk to operations, which means our ability to operate the transportation facilities without risk for the public.

If we have to close a bridge because some aspects went out of control, such as conditions that deteriorated the bridge to the point that no longer can carry loads, this interferes with our operations and the use of the bridge by the public. People expect to go from point A to B at their desire, without delay or inconvenience. In my opinion a lot of what we do with bridge preservation is really aimed at insuring our ability to maintain infrastructure operations.

Bridge preservation also helps maximize benefits from the investments we make, taking into account we do not have enough money for the many different needs that we face.  The way funds are applied in order to achieve maximum benefits and risk control is what bridge preservation means to me.

Some people look at bridge preservation from the financial aspect, i.e. maximize life-cycle cost and investments, but this other element, operations, sometimes slides under the radar screen while it is actually one of the major components of bridge preservation. By maintaining awareness through inspection and applying the appropriate treatment early, whether through preservation or maintenance, we are controlling operation risk.  Closing infrastructures is more than an inconvenience for users, it is an issue related to safety.

Can you speak of the bridge preservation strategy at WisDOT?

Our strategy stems from some of the changes we are all going through with MAP 21 and FAST Act, which mandated changes that represent opportunities to do things differently and perhaps better.

With regards to the new AASHTO inspection elements, we decided to use our already good inspection program in a broader way, as the foundation of a concept strategy that will allow us to maintain bridges in a more systematic manner. Inspection data are at the core of WisDOT 2016 Bridge Preservation Policy Guide (see below), which was developed with contribution from national experts, our own staff as well as regional bridge practitioners. The Policy Guide, which sets out the framework for performance goals for bridges, NBI and element level goals, created a series of work rules for different actions that must be taken for bridge preservation.

By combining inspection information with work rules, the Policy Guide indicates specific needs for actions related for example to the deterioration of concrete deck, steel girder, expansion joints or bearings. It provides a structured approach to problems, thereby avoiding subjectivity and inconsistency.

The next effort at WisDOT will entail upgrading to our bridge management system as well as developing an asset management program, which all lead to the ability to systematically identify work needs and provide means to establish projects and bridge programs.  Deterioration capabilities are key elements since we want to be able to look out in the future and predict our needs in 5 – 20 years based on current conditions.

Could you elaborate on the work rules?

In a nutshell, the inspection program, the preservation policy, the automation bridge management system all lead to the implementation of a data driven program, which connects information from different sources and provides work rules.

I would like to add that this interactive program can be very helpful to the younger staff, who will not have to spend years of learning before they are able to make decisions and implement actions.

What challenges are you facing in the implementation of the bridge preservation strategy?

In addition to the fact that we have limited dollars to support the program, there is need for more research in certain areas.

We have a good understanding of some mechanisms that influence the deterioration of bridges and how some of the treatments help but there is quite a bit of variability.  We need more confident estimates of when it is time to redo preservation applications, for example, bridge deck overlays and penetrating sealers.

We have a lot of interest in deterioration curves which can allow the optimization of investments and performance.

While different strategies can be used throughout the life-cycle of a bridge, our challenge is to research and adopt the optimal strategy for our environment. Technologies that work in a different climate can very likely be of no use to successfully maintain the 15,000 bridges of the state of Wisconsin.

Is there any bridge preservation success story you would like to share?

Probably the development of our Bridge Preservation Policy Guide and some aspects of our automation systems related to bridge management.

We made a lot of upgrades with our bridge management system supporting the use of mobile devices to do bridge inspections. We can currently conduct a bridge inspection through an I-Pad or a smart phone, which allow downloading information and uploading inspection results. If something critical that can compromise the loading carrying capability of a bridge is found, the bridge rating engineer is alerted almost immediately from the field. The engineer can therefore provide instructions for further information when the inspector is still in the field.

What are the goals of your department in 2017 and as well the long term?

Moving forward we want to do further implementation of our asset management investment process. While it is one thing to build technology and rules, it is a different thing to integrate them into the business process. We are working with investment people and regional people making sure they understand the tool we have and have the opportunity to tell us what they need from it.

I am looking forward to continue working with the TSP2 Partnership in order to try building more uniformity and consistency between Midwestern States in practices, details, policies and specifications, where appropriate and applicable.

Reaching a certain level of consistency between States that share similar climate can bring significant benefits to both DOTs and to industry. As an example, if contractors can work easily in more than one State, they have more opportunities for business while DOTs can benefit from increased competition. Contractors are currently fairly localized to one State since they have to learn new sets of information and rules as they move from one State to another.

The TSP2 Partnership plays a very important role in facilitating dialogue and exchange between DOTs and industry.  While at DOTs we sometimes see ourselves in a mirror, industry can provide insights across the borders and suggest higher level of uniformity in specifications, guidelines and approved product lists.

LINKAGE

• WisDOT 2016 Bridge Preservation Policy Guide

http://wisconsindot.gov/dtsdManuals/strct/manuals/preservation/wisdot-prsv-pol.pdf

• Wisconsin DOT Bridge Asset Management presentation by Bill Oliva at 2016 MWBPP Meeting in Milwaukee, WI

http://pavementvideo.s3.amazonaws.com/2016_MWBPP/4_Wisconsin%20DOT%20Bridge%20Asset%20Management_Oliva.pdf

Nancy Huether (NDDOT)

Author: Lorella Angelini, Angelini Consulting Services, LLC

At the recent TSP2 MWBPP meeting in Milwaukee I met Nancy Huether, Transportation Engineer with the North Dakota Department of Transportation (NDDOT), who is the chair of the TSP2 Midwest Bridge Preservation Partnership Board of Directors.  I had a chance to speak with Nancy about bridge preservation strategies and implementation challenges in her state.

What does bridge preservation entail at NDDOT?

The bridge preservation program at NDDOT is still being defined. It is a given that focusing on bridge maintenance is one of our main goals. However, bridge preservation should be considered during all phases of the life of a bridge from conscientious design and construction to timely rehabilitation.

I believe strongly that bridge preservation starts with design and construction, which are critical elements in making sure we have good bridges and we can maintain them.  In other words, it is challenging to maintain bridges if they are not designed properly or constructed according to specifications.

I understand the design part. Could you tell me more about the construction aspect? Do you mean choosing the right materials and applying them correctly?

Yes, proper construction is very important. For example, when placing concrete it is important to consider ambient conditions such as temperature, wind, and humidity. Proper curing is also a critical component in ensuring long-lasting well-performing concrete.

I would like to reinforce the concept that preservation entails more than just maintenance. Construction plays a big part and cannot be overlooked.

Could you also speak of the design part? 

Using design methods that minimize maintenance is critical.  For example, the bridge division has been designing bridges for many years with integral abutments that minimize or eliminate the need for joints and the maintenance headaches that come along with them.

I understand that you have been in your new bridge preservation management position for about one year. Can you speak of this appointment?

I am a Registered Professional Engineer in the Bridge Division.  Just over a year ago, I was tasked with switching from the Hydraulics Section to the Structure Management Section to start a bridge preservation program.

Prior to my appointment, the NDDOT had no formal bridge preservation program.  That is not to say preservation concepts were not understood and considered, but there was no formal program. Bridge Preservation only entailed the Bridge Maintenance section that was added to the Maintenance Operations Manual in 2008.  This section, which was developed with the help of Bridge and District employees, laid out maintenance tasks and a schedule for completing those tasks.

What is your role with the Districts?

I do not supervise the implementation of bridge preservation in the eight Districts of the NDDOT.  My role is to support the Districts in their efforts by assisting with requests for education or by providing information about bridge preservation materials and procedures.

Encouraging Districts to focus more on bridge preservation activity and understand its value is one of my main goals. For this reason, as soon as I got the new bridge preservation assignment, I went to visit each District and learn about what they were doing.  The amount of bridge preventative maintenance being done in the eight Districts varied from a lot to very little.  The NDDOT is fortunate to have very capable maintenance personnel and I am confident that with additional support they can do much more.

What have you done so far?

I am in the process of developing the bridge preservation program. The first step of the program, which is nearly complete, is updating the Bridge Maintenance section of the Maintenance Operations Manual with current materials and best practices. We want to give more value to the Manual and see bridge maintenance operations more fully adopted by all the Districts.

The second step of the program entails finalizing a bridge preservation strategy that will eventually include not only maintenance, but also design, construction, and rehabilitation.

What is the major challenge that you are facing?

One major challenge involves getting more of the District personnel to better understand the benefits and importance of bridge preservation.  Since the NDDOT does not have dedicated bridge maintenance crews, bridge maintenance is only one of the many maintenance tasks the District Maintenance Sections are responsible for completing.

The bridges in North Dakota are in fairly good condition. However, sometimes when bridges are in need of repair, maintenance is deferred until small problems become bigger problems and contractors are called on to do the work.  This is a reactive mode of action.  Embracing the preservation concept means focusing on preventative maintenance and taking care of small problems before they become big problems. Increasing the awareness and benefits of pro-active maintenance will help us keep our good bridges good.

Do you have a bridge preservation success story you would like to share with the readers?

Yes, it is about the pro-active actions taken by one of our Districts. Approximately two years ago a District employee who has always had a keen interest in bridge preservation, was put in charge of maintenance for that District, where little bridge preventative maintenance had previously been done.

Under the guidance of this employee, the District has implemented a bridge deck preservation program that includes sweeping and washing the deck, sealing cracks with epoxy, and applying a silane surface treatment.

Although prescribed in the Maintenance Operations Manual, silane sealers had never before been applied by NDDOT maintenance crews.

The District developed the silane surface treatment application equipment and process on its own. It encompassed designing, assembling, and calibrating the spray equipment including spray bar, nozzles, tractor, pump and tank. They successfully treated several bridge decks this year.

At what time do you apply silane sealers as a bridge deck protection?

We apply the silane deck surface treatment as part of the initial construction, as soon as the bridge deck is completed and the concrete is cured. In doing so, the application becomes part of the design and the construction project.  We then prescribe the reapplication on a 6 year cycle.

Could you talk of your goals for 2017 and the upcoming years?

I have two main goals. The first is to assist our maintenance forces to continue taking initiatives and doing new maintenance activities in line with pro-active bridge preservation.  My role is to support them with information about products, processes, training, tracking, and any other areas needed, to the best of my ability.  This support, combined with their extensive knowledge and field experience, will help us achieve this goal.

My second goal is to get NDDOT bridge preservation program well documented, funded, and solidified.  The program will define the overall purpose of bridge preservation and outline key elements such as objectives, performance measures, and goals that support the NDDOT Strategic Business Plan. This program will also define a systematic approach to project selection and provide guidance for appropriate preservation strategies.  A well-defined bridge preservation program is important in cost effectively managing and preserving the NDDOT’s bridges.

Can TSP2 help NDDOT reach its goals? Is there more that TSP2 can do for you?

TSP2 continues to play a significant role in developing our bridge preservation program. I regularly use the information that is available on their web site.

TSP2 Regional and National Partnership Meetings are also of great value. They have given me, as well as others at the NDDOT, the opportunity to make connections with bridge preservation experts at other State DOTs, as well as with industry members, consulting engineers and contractors.

It is truly invaluable to be able to talk to people in other states about what they are doing and what has worked in solving specific bridge preservation problems. Thanks to TSP2 and the bridge partnerships, I have a large group of knowledgeable peers I can reach out to when questions or issues arise.  I can send one e-mail and receive 20 replies.

There is always something more that can be done. My hope is that TSP2 continues to strengthen its role as collector of information.  The TSP2 web site should be the first place people can go to find information, research, and publications about bridge preservation.

Pete Weykamp at LTAP Conference, Purdue University

Author: Lorella Angelini, Angelini Consulting Services, LLC
After leading the bridge preservation program with New York State DOT, Pete Weykamp has put his knowledge and experience at the service of the Local Technical Assistance Program (LTAP). Together with Ed Welch, Bridge Preservation Engineer for the AASHTO TSP-2 Program, and with the support of the National Center for Pavement Preservation (NCPP), Pete has started the Bridge Preservation LTAP training track for Local Agencies. I reached out to Peter in order to know more about the program. Additional information is reported in the flier, see linkage at the end of the post.

• Could you speak of the reasoning behind the newly introduced Bridge Presevation training?

Over the last few years there has been great interest in getting Local Agencies (Cities, Counties & Towns) “up to speed” on the maintenance and preservation of their bridges.  In response to these needs Ed Welch and I have developed and implemented an Introductory/Grass Roots Bridge Preservation LTAP course for Local Agencies. The course is focused on the concept of bridge preservation and the advantages that it generates. It can be tailored to individual audiences adding or dropping topics depending on their capabilities and needs. The course can be presented as a full or half day as time permits.

Understanding the need for training and the development of municipal programs specific to the preservation of the non-State owned bridges is vital to the overall condition of the Country’s 608,000 bridges.  An effective/balanced bridge preservation program should include all aspects of preservation, first and foremost both reactive and proactive maintenance.

• What is the target audience for the training program?

Our target audience consists of bridge maintenance personnel working for Local Agencies.  We have the ability to modify the training sessions based on the make-up of the different audience groups.  For example, for an audience of county highway supervisors and engineers we focus on Why specific preservation actions are necessary.  For an audience made up of field crews, a greater focus is place on How the actions are performed.  

• Can you speak of the short and long term goals of the program?

Short term goals focus on a holistic approach to managing highway structures at the local level.  This includes topics that are essential for the preservation of locally-owned highway structures, such as involving industry partners and formalizing a process to deliver needed training.  

Longer term goals create a mechanism for local officials and crews to network, view hands-on demonstrations, and provide opportunities to participate in the AASHTO Regional Bridge Preservation Partnerships.

• What is your specific role?  

My role is to develop training modules and provide instruction to for local agency training.  Working with Ed, we created training modules on Concrete Washing and Sealing, Expansion Joints, Repairing Concrete, Programming Bridge Maintenance, Developing a Bridge Preservation Program, and an overview presentation on Bridge Preservation Training for LTAP.  

I am currently working on training modules for Steel Coatings, Bolting, and Bearing Maintenance.  The modules will include videos and demonstrations.  I will continue to seek the assistance of industry partners in developing the training modules.  

• How much was implemented in 2016 and what is expected in 2017

During the current year, training modules on Concrete Washing and Sealing, Expansion Joints, Repairing Concrete, Programming Bridge Maintenance, Developing a Bridge Preservation Program, and an overview presentation on Bridge Preservation Training for LTAPs were developed.  

In October, Ed and I conducted a training session during an event hosted by the Indiana LTAP through Purdue University.  Approximately 100 county highway supervisors participated in sessions on Expansion Joints, Programming Bridge Maintenance, and Concrete Repair.  An industry representative conducted a demonstration on the use of chemical anchors.  The half-day of bridge preservation training was received with substantial interest.    

For 2017, additional modules on the Protection of Structural Steel, Deck Overlay Options, Scour Remediation, and the Use of Sacrificial Anodes will be created. TSP2 will continue to outreach to Local Agencies offering bridge preservation training and the resources available through its program. TSP2 will also continue to explore needs and applications suitable for bridge preservation actions that can be implemented at the local level.

LINKAGE:

LTAP National Program

National LTAP & TTAP Association

Indiana LTAP – County Bridge Conference

Bridge Preservation Flyer for the LTAP Program

Author: Lorella Angelini, Angelini Consulting Services, LLC

I met Ed Lutgen Regional Bridge Construction Engineer with Minnesota DOT (MnDOT) at the Bridge Office in Oakdale, MN. We had a long conversation about bridge preservation strategies with the DOT and its implementation policies.

1. What criteria does MnDOT use to classify bridge preservation? Is the MnDOT classification different from FHWA?

MnDOT classification for bridge preservation is slightly different from FHWA. In its “Bridge Preservation and Improvement Guidelines” MnDOT has created two categories: Preservation and Improvement. Bridge Rehabilitation and Bridge Replacement are classified under Improvement whereas FHWA classification places Bridge Rehabilitation under Preservation.

In the past we had four different levels: Preservation, Improvement, Rehabilitation and Replacement. Preservation was defined as less than 30% of a new bridge cost, Improvement from 30 to 60%, Rehabilitation from 60 to 70%, Replacement was recommended when the repair costs exceeded 70% of a new bridge costs.

Since we were not doing many rehabilitation projects as defined in the previous system, we included Bridge Rehabilitation into Improvement. Within Preservation we also made a distinction between Bridge Maintenance and Major Preservation.

Preservation entails repairing deteriorated bridges with no significant change to their geometry or increase of load carrying capacity.  In a nutshell, it means preserving what is currently in place.  Concrete repair and cathodic protection are examples of typical preservation activities. Usually a preservation project is not meant to last more than 10-20 years and does not require bringing the bridge up to new design standards. However the bridge must comply with safety standards.

On the other hand, improvement applications entail modifying the geometry of the bridge and/or increasing its loading capacity. Rehabilitation projects are meant to last 50 years or longer and must meet specific design standards. Replacement projects have higher design requirements since they must meet full standards.

2. Could you talk about the “Bridge Preservation and Improvement Guidelines”?

The Bridge Condition diagram is the focal element of the guidelines. It has been designed to be in line with AASHTO Subcommittee on Bridges and Structures (SCOBS) recommendations with regards to flow and targets to meet. However, we adapted the diagram to MnDOT bridge preservation classification and we linked it to National Bridge Inventory (NBI) General Terms. As a consequence, Bridge Maintenance (Green Code) entails NBI from 7 to 9, Major Preservation (Yellow Code) from 5 to 6 and Improvement (Red Code) from 4 to 0.

3. Could you speak about the project classification table?

The table provides a general guidance about scope of work and cost for MnDOT four preservation and improvement categories: Bridge Maintenance, Major Preservation, Bridge Rehabilitation and Bridge Replacement.

As an example, if a major preservation project entails spending 80% of the cost of a new bridge, then the project does not meet the criteria indicated in the table. According to MnDOT, a costly project should provide more benefits than limited service life improvement and no increase of load carrying capacity. In other words, we do not want to spend 80% of the cost of a new bridge without significantly affecting key parameters such as service life, load carrying capacity and bridge geometry. However, there are exceptions that are evaluated case by case.

4. Could you explain MnDOT decision-making process for the implementation of preservation and improvement projects?

The first step entails bridge safety inspection and NBI ratings, which are under the responsibility of District engineers. In Minnesota we have 8 Districts, each managing between 200 and 1500 bridges.

Data from the Districts is introduced in the Bridge Replacement and Improvement Management (BRIM) software program, which compiles the conditions of all bridge elements and calculates the probability for bridge service interruption.

BRIM uses deterioration curves to project bridge conditions out 20 years into the future.  We developed 6 different deterioration curve models for bridges in our State. In projecting MnDOT bridge inventory into the future, BRIM identifies bridges that are candidates for preservation or improvement projects. The software uses engineering logic and a data base that includes conditions and other critical factors, such as Average Daily Traffic (ADT).

In summary, in a 20-year period BRIM is able to project the time frame for a particular bridge to be repaired and it also recommends the type of repair, whether rehabilitation or preservation.

5. How do you use information from BRIM?

Every year District engineers evaluate the BRIM output and make an intelligent decision on whether to advance or push back bridges in the priority list. This decision is taken in conjunction with the Bridge Office. As an example, we can foresee that a remote bridge will last longer than expected because it does not get a lot of wear and tear and de-icing chemicals are seldomly used.

Once a Bridge Performance Index (BPI) is established for each bridge, the next step of the process entails a spending evaluation through State Transportation Improvement Program (STIP). In essence, this is a funding mechanism that allows knowing what we will be spending for each bridge in 4 years before letting.

In order to avoid focusing on riskier bridges only, the BPIG recommended output should include 50% replacements, 25% rehabilitation and 25% preservation projects. This criteria prevents us to go back to the “worst come first” criteria, which is not in line with an asset management strategy.

Not all the Districts can meet the 50-25-25 criteria though. In the metro areas we are going to have a major bubble of rehabilitation projects in the coming years. I-94, which was built between the 60ies and the 70ies, has bridges that are becoming 50 years old. Since we cannot do all the necessary rehabilitation projects at one time, we are implementing preservation strategies in order to extend the service life of critical structural elements, such as bridge decks.

In the late 70ies and 80ies we did an overlay program that entailed overlaying 90% of our bridges decks with 2 inches of low slump concrete. In the last 5 years we have started re-overlaying bridge decks as part of a bridge preservation strategy. We have seen between 20 and 30 years of extended service life for low slump concrete overlays. However, an old deck with black bars is sometimes not worth another overlay. We also do not want to improve the deck of a bridge that has a 100-year old substructure. Ideally we would like all the different bridge elements to end at the same time.

6. What about bridge preservation strategy for bridges in the rural areas?

The service life of rural bridges is on average longer than in the metro area where traffic demand requires the implementation of a significant number of rehabilitation and replacement projects.

Service life of bridges that belong to the County system is even longer than DOTs. Because of limited funds, Counties must allow bridges to get into conditions defined by low NBI rates, which, in some circumstances, can cause bridge service interruption.

With few exception, such as Hennepin County, City of Minneapolis and Duluth that have preservation procedures in place, Counties are in a reaction mode and adopt a “worst comes first” policy, which is mainly focused on bridge replacement.

7. Back to the decision-making process, how does it develop when it gets to STIP?

District engineers calculate cost of projects in the BRIM – BPI output list that are related to their region and the 4-year program.  To do so they use a cost estimated worksheet that is included in the Guidelines. Once the cost of each project is defined, the information is introduced into the STIP, which provides the amount of spending by year and, as a result, defines the number of projects that can be implemented.

About one and half year before the letting, one of the Regional Bridge Construction engineers performs a field site visit together with a District engineer.  They walk individual bridges and complete a field review. This only entails preservation and rehabilitation projects, not replacement. A safety inspection is also performed.

For routine inspections, all non-culvert bridges are inspected every 24 months. If a bridge is classified NBI 4 or less (poor condition), then it gets inspected every 12 months.

Approximately one year from the letting, the Regional Bridge Construction engineer writes a recommendation report for preservation and rehabilitation projects. The report specifies actions to be taken but also includes information about estimated quantities. Basically the report works as a preliminary plan.

Once the recommendation report is signed off by the Districts, it comes back to the Bridge Office where design engineers start developing the contract plan and special provisions.  All repair recommendations reports are written by one of the four Regional Bridge Construction engineers, thus creating consistency between the reports and providing a level of quality control.

Districts also evaluate whether certain actions can be implemented by their own maintenance force. Each District has from 1 to 5 maintenance crews for a total of 190 bridge maintenance workers around the State. District maintenance crews usually perform jobs such as deck crack sealing, bearing greasing, concrete repair or joint replacements. Some Districts are able to perform more complex work, such as Accelerated Bridge Construction (ABC), overlays, painting, gusset plate replacement and even bridge replacements.

8. When you mention a project, do you refer to a single bridge? Or can a project entail multiple bridges?

A project can encompass a number of bridges. We are about to start the North Lowry tunnel project, which includes 52 bridges from Nicollet Ave to Shingle Creek on I94. Out of the 52 bridges only 1 entails rehabilitation, the other 51 concern preservation for a total of $15 M. We are planning to do patching, overlays, concrete repairs, delamination removal, Fiber Reinforced Polymer (FRP) and Glass Fiber Reinforced Polymer (GFRP) applications. These last two technologies will be used as strengthening system but also to make repairs last longer in areas close to traffic where there is salt spray.

For a major project like this we hired a consulting engineer, to help with field investigation and preparing the final design. Repair recommendations for all bridges were developed by a Regional Bridge Construction engineer.

9. What happens after the letting?

Once a contract is awarded, the Regional Bridge Construction engineers support the contractor for any questions or issues they may have.

At contract completion, bridges can be upgraded according to NBI rating. However they can also maintain the same ratings.

10. Do you have a preservation success story that you would like to share?

We are proud of the restoration of the Lester River Bridge over the mouth of the Lester River along Lake Superior shoreline, which was built in 1924-25.  It is a beautiful arch bridge that is considered as a gateway to the North Shore. It has masonry abutments and side walls over the concrete arch.

Due to the high level of chloride contamination, we had to remove all masonry down to the top of the arch and apply a comprehensive cathodic protection system that included a variety of solutions suited to different conditions. In addition to design standards, we met the standards from historic preservation.

11. What can TSP2 do for you?

We consider TSP2 as an organization that can help us get information about new products and technologies for bridge preservation and rehabilitation, especially in relation to service life extension and cost-benefit. We are also interested in knowing of other States’ experience with new technologies, in particular in the Midwest.

We have started evaluating the use of GFRP rebars for bridge decks so as to avoid steel corrosion. We currently use epoxy coated steel bars for bridges that cost less than $25 M. For bridges that cost more than $25 M we use stainless steel bars.

We are also evaluating the use of GFRP bars in the substructure areas that are more prone to deterioration, such as underneath deck joints or abutment seats. Leaking joints are a source of problems since they cause concrete deterioration and spallings in the substructure. We tend to eliminate joints whenever it is possible.

We have started using other innovative technologies, such as micro and macro fibers in casting decks and epoxy chip seal especially, in situations where we have deck cracking.

We are doing Accelerated Bridge Construction (ABC) and we are addressing mass concrete issues.

In addition to new products and technologies, we are also interested in getting information about prioritization of applications in other DOT States and successful solutions that solved specific problems.

LINKAGE:

Minnesota DOT “Bridge Preservation and Improvement Guidelines – Fiscal Year 2016 through 2010” – http://www.dot.state.mn.us/bridge/pdf/bridge-preservation-and-improvement-guidelines-2016-2020.pdf

Joshua with the kids of Panama

Author: Lorella Angelini, Angelini Consulting Services, LLC

Some time ago I published a post about the initiative taken by Joshua Sletten, Utah DOT, who traveled to Lura, Panama to help build a pedestrian suspension bridge with the “Bridges to Prosperity” organization.

I met Joshua at the recent AASHTO Subcommittee on Bridges and Structures (SCOBS) annual meeting in Minneapolis, MN, where I live. Joshua, an expert on bridge preservation, sits on the AASHTO SCOBS technical committee T-9 “Bridge Preservation” that is chaired by Bruce Johnson with Oregon DOT.

I had a brief conversation with Joshua about his experience in Panama.

Was the goal accomplished? Did the construction of the suspended pedestrian bridge in Panama go as planned? 

Yes, the goal was fully accomplished. We actually completed the bridge a little faster than we had scheduled.  We had planned to complete the project in 12 days, and we finished after 8. We also finished under budget. I think everybody was pretty happy with it.

We worked well together as a team. We brought in local community members that helped us build the entire bridge. We had translators to help with language differences. Everybody played their part well.

What was your role in the project?

I was the logistic manager, in charge of getting everybody to the bridge at the scheduled time. I also managed transportation, arranging meals and lodging in Panama City.

 What stands out in your memory about this experience?

The biggest thing for me was connecting with people, the volunteers that traveled to Lura, Panama to help build the bridge and the local community. I also had a great time playing with the local children. After work, we played kickball, softball and football. I even taught the kids how to throw a Frisbee.

I will surely remember the inauguration day, when we played music during a traditional jam.

The other big thing that stands out to me is having been able to build a bridge that was desperately needed by the community. The bridge will serve the community for generations to come. This is what makes me proud to be an engineer. I am definitively going to remember this.

Would you recommend this experience to other engineers?

I learned a lot from this experience. I arrived to the bridge location, deep in the Panamanian jungle, got unplugged from all the technology and started working with a team that was motivated and like-minded to build a 150 ft. long suspension bridge  in a short amount of time.

It was a memorable, once in a lifetime experience that I highly recommend to anyone.

Obviously, one has to overcome some challenges, like staying in a tent, doing hard work and labor with your hands, and not being afraid of sun exposure or getting attacked by mosquitoes.

How long did you stay in Panama?

I was there for two weeks. When I got there the local community had already completed the foundation. The entire bridge, from inception to inauguration, took approximately three months to build.

Will there be any preservation activity for the bridge that you helped build?

We spoke at length with the local people, who are very proud of the bridge, about the importance of proper bridge maintenance.  We wanted to reinforce the concept that in order to keep the bridge in a state they can be proud of for years to come, it has to be well maintained. We talked to them about how to replace the planks when they begin to wear out. We showed them how to maintain or replace other critical elements of the bridge.