In the years since the Federal Highway Administration's landmark publication, Bridge Inspector’s Training Manual 90 (Manual 90), bridge inspection and inventory programs of state and local governments have formed an important basis for formal bridge management programs. During the 1990’s, the state DOT’s implemented comprehensive bridge management systems, which rely heavily on accurate, consistent bridge inspection data.
This manual, the Bridge Inspector’s Reference Manual (BIRM), updates Manual 90 and reflects over 20 years of change.
Advances in technology and construction have greatly enhanced current bridge design. However, the emergence of previously unknown problem areas and the escalating cost of replacing older bridges make it imperative that existing bridges be evaluated properly to be kept open and safe.
There are four letters that define the scope of bridge inspections in this country: NBIS, meaning National Bridge Inspection Standards. The National Bridge Inspection Standards (NBIS) are Federal regulations establishing requirements for:
The National Bridge Inventory (NBI) is the aggregation of structure inventory and appraisal data collected by each state to fulfill the requirements of NBIS.
To better understand the National Bridge Inventory Program (NBIP), it is helpful to review the development of the program
Figure 1.1.1 Number of Bridges Built since 1900
During the bridge construction boom of the 1950’s and 1960’s, little emphasis was placed on safety inspection and maintenance of bridges. This changed when the 2,235-foot Silver Bridge, at Point Pleasant, West Virginia, collapsed into the Ohio River on December 15, 1967, killing 46 people (see Figure 1.1.2).
Figure 1.1.2 Collapse of the Silver Bridge
This tragic collapse aroused national interest in the safety inspection and maintenance of bridges. The U.S. Congress was prompted to add a section to the “Federal Highway Act of 1968” which required the Secretary of Transportation to establish a national bridge inspection standard. The Secretary was also required to develop a program to train bridge inspectors.
Thus, in 1971, the National Bridge Inspection Standards (NBIS) came into being. The NBIS established national policy regarding:
Three manuals were subsequently developed. These manuals were vital to the early success of the NBIS. The first manual was the Federal Highway Administration (FHWA) Bridge Inspector’s Training Manual 70 (Manual 70). This manual set the standard for inspector training.
The second manual was the American Association of State Highway Officials (AASHO) Manual for Maintenance Inspection of Bridges, released in 1970. This manual served as a standard to provide uniformity in the procedures and policies for determining the physical condition, maintenance needs and load capacity of highway bridges.
The third manual was the FHWA Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation’s Bridges (Coding Guide), released in July 1972. It provided thorough and detailed guidance in evaluating and coding specific bridge data.
With the publication of Manual 70, the implementation of national standards and guidelines, the support of AASHO, and a newly available FHWA bridge inspector’s training course for use in individual states, improved inventory and appraisal of the nation’s bridges seemed inevitable. Several states began in-house training programs, and the 1970’s looked promising. Maintenance and inspection problems associated with movable bridges were also addressed. In 1977, a supplement to Manual 70, the Bridge Inspector’s Manual for Movable Bridges, was added.
However, the future was not to be trouble free. Two predominant concerns were identified during this period. One concern was that bridge repair and replacement needs far exceeded available funding. The other was that NBIS activity was limited to bridges on the Federal Aid highway systems. This resulted in little incentive for inspection and inventory of bridges not on Federal Aid highway systems.
These two concerns were addressed in the “Surface Transportation Assistance Act of 1978.” This act provided badly needed funding for rehabilitation and new construction and required that all public bridges over 20 feet in length be inspected and inventoried in accordance with the NBIS by December 31, 1980. Any bridge not inspected and inventoried in compliance with NBIS would be ineligible for funding from the special replacement program.
In 1978, the American Association of State Highway and Transportation Officials (AASHTO) revised their Manual for Maintenance Inspection of Bridges (AASHTO Manual). In 1979, the NBIS and the FHWA Coding Guide were also revised. These publications, along with Manual 70, provided state agencies with definite guidelines for compliance with the NBIS.
The National Bridge Inspection Program was now maturing and well positioned for the coming decade. Two additional supplements to Manual 70 were published. First, culverts became an area of interest after several tragic failures. The 1979 NBIS revisions also prompted increased interest in culverts. The Culvert Inspection Manual was published July 1986. Then, an emerging national emphasis on fatigue and fracture critical bridges was sharply focused by the collapse of Connecticut’s Mianus River Bridge in June 1983. Inspection of Fracture Critical Bridge Members was published in September 1986. These manuals were the products of ongoing research in these problem areas.
With the April 1987 collapse of New York’s Schoharie Creek Bridge, national attention turned to underwater inspection. Of the over 593,000 bridges in the national inventory, approximately 86% were over waterways. The FHWA responded with Scour at Bridges, a technical advisory published in September 1988. This advisory provided guidance for developing and implementing a scour evaluation program for the:
Further documentation is available on this topic in the Hydraulic Engineering Circular No. 18 (HEC-18).
In September 1988, the NBIS was modified, based on suggestions made in the “1987 Surface Transportation and Uniform Relocation Assistance Act,” to require states to identify bridges with fracture critical details and establish special inspection procedures. The same requirements were made for bridges requiring underwater inspections. The NBIS revisions also allowed for adjustments in the frequency of inspections and the acceptance of National Institute for Certification in Engineering Technologies (NICET) Level III and IV certification for inspector qualifications.
In December 1988, the FHWA issued a revision to the Coding Guide. This time the revision would be one of major proportions, shaping the National Bridge Inspection Program for the next decade. The Coding Guide provided inspectors with additional direction in performing uniform and accurate bridge inspections.
The 1990’s was the decade for bridge management systems (BMS). Several states, including New York, Pennsylvania, North Carolina, Alabama and Indiana, had their own comprehensive bridge management systems.
In 1991, the FHWA sponsored the development of a bridge management system called “Pontis” which is derived from the Latin word for bridge. The Pontis system has sufficient flexibility to allow customization to any agency or organization responsible for maintaining a network of bridges.
Simultaneously, the National Cooperative Highway Research Program (NCHRP) of the Transportation Research Board (TRB) developed a BMS software called “Bridgit.” Bridgit is primarily targeted to smaller bridge inventories or local highway systems.
As more and more bridge needs were identified, it became evident that needed funding for bridge maintenance, repair and rehabilitation (MR&R) far exceeded the available funding from federal and state sources. Even with the infusion of financial support provided by the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991, funding for bridge MR&R projects was difficult to obtain. This was due in part to the enormous demand from across the nation. An October 1993 revision to NBIS permitted bridge owners to request approval from FHWA of extended inspection cycles of up to forty-eight months for bridges meeting certain requirements.
In 1994, the American Association of State Highway and Transportation Officials (AASHTO) revised their Manual for Condition Evaluation of Bridges (AASHTO Manual). In 1995, the FHWA Coding Guide was also revised. These publications, along with Manual 90, Revised July 1995, provided state agencies with continued definite guidelines for compliance with the NBIS and conducting bridge inspection.
Although later rescinded in the next transportation bill, the ISTEA legislation required that each state implement a comprehensive bridge management system by October 1995. This deadline represented a remarkable challenge since few states had previously implemented a BMS that could be considered to meet the definition of a comprehensive BMS. In fact, prior to the late 1980’s, there were no existing management systems adaptable to the management of bridge programs nor was there any clear, accepted definition of key bridge management principles or objectives.
This flexibility in the system was the result of developmental input by a Technical Working Group (TWG) comprised of representatives from the FHWA, the Transportation Research Board (TRB) and the following six states: California, Minnesota, North Carolina, Tennessee, Vermont and Washington. The TWG provided guidance drawing on considerable experience in bridge management and engineering.
The National Highway System (NHS) Act of 1995 rescinded the requirement for bridge management systems. However, many of the states continued to implement the Pontis BMS.
The Transportation Equity Act of the 21st Century (TEA-21) was signed into law in June 1998. TEA-21 built on and improved the initiatives established in ISTEA and, as mentioned earlier, rescinded the mandatory BMS requirement.
In 2002, Manual 90 was revised and updated as a part of a complete overhaul of the FHWA Bridge Safety Inspection training program. The new manual was named the Bridge Inspector’s Reference Manual (BIRM) and incorporated all of Manual 90. The BIRM also incorporates manual 70 Supplements for culvert inspection and Fracture Critical Members. The BIRM was also updated in 2011.
On December 14, 2004, the revised NBIS regulation was published in the Federal Register. The updated NBIS took affect January 13, 2005. Implementation plans were to be developed by April 13, 2005 to be fully implemented by January 13, 2006.
The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) was signed into law in August 2005. SAFETEA-LU represents the largest surface transportation investment in the Nation’s history. SAFETEA-LU builds on and improves the initiatives established in ISTEA and TEA-21. Since being signed into law in August 2005, SAFETEA-LU has undergone several extensions past its original 2009 expiration, resulting in guaranteed funding until the end of Fiscal Year (FY) 2011. Multi-year legislation is expected to provide funding following FY 2011.
Over the years, varying amounts of federal funds have been spent on bridge projects, depending on the demands of the transportation infrastructure. Figure 1.1.3 illustrates the fluctuations in federal spending and shows current trends.
Figure 1.1.3 Federal Funding Levels (1979 – 2003)
Much has been learned in the field of bridge inspection, and a national Bridge Inspection Training Program is now fully implemented. State and federal inspection efforts are more organized, better managed and much broader in scope. The technology used to inspect and evaluate bridge members and bridge materials has significantly improved.
Areas of emphasis in bridge inspection programs are changing and expanding as new problems become apparent, as newer bridge types become more common, and as these newer bridges age enough to have areas of concern. Guidelines for inspection ratings have been refined to increase uniformity and consistency of inspections. Data from bridge inspections has become critical input into a variety of analyses and decisions by state agencies and the Federal Highway Administration.
The NBIS has kept current with the field of bridge inspection. The 2005 National Bridge Inspection Standards appear in Appendix A. The standards are divided into the following sections:
The FHWA has made a considerable effort to make available to the nation’s bridge inspectors the information and knowledge necessary to accurately and thoroughly inspect and evaluate the nation’s bridges.
The FHWA has developed and now offers the following training courses relative to structure inspection through the National Highway Institute (NHI):
Throughout all the expansions and improvements in bridge inspection programs and capabilities, one factor remains constant: the overriding importance of the inspector’s ability to effectively inspect bridge components and materials and to make sound evaluations with accurate ratings. The validity of all analyses and decisions based on the inspection data is dependent on the quality and the reliability of the data collected in the field.
Across the nation, the duties, responsibilities, and qualifications of bridge inspectors vary widely. The two keys to a knowledgeable, effective inspection are training and experience in performing actual bridge inspections. Training of bridge inspectors has been, and will continue to be, an active process within state highway agencies for many years. This manual is designed to be an integral part of that training process.
Bridge inspection has played, and continues to play, an increasingly important role in providing a safe infrastructure for the United States. As the nation's bridges continue to age and deteriorate, an accurate and thorough assessment of each bridge’s condition is critical in maintaining a safe, functional and reliable highway system.
This topic presents the responsibilities of the bridge inspector/engineer and qualifications for bridge inspection personnel.
There are five basic responsibilities of the bridge inspector and engineer:
The primary responsibility of the bridge inspector is to maintain public safety and confidence. The general public travels the highways and bridges without hesitation. However, when a bridge fails, the public’s confidence in the bridge system is violated (see Figure 1.2.1).
The engineer’s role is:
Engineers include a margin of safety in their designs to compensate for variations in the quality of materials and unknowns in vehicular traffic loadings through the life of the structure. In older bridges, especially those designed prior to the use of computer software programs and modern design codes, margin of safety also compensated for a lack of precise calculations and construction loading conditions.
The inspector’s role is:
Figure 1.2.1 Mianus Bridge Failure
Another responsibility is to protect public investment in bridges. Be on guard for minor problems that can be corrected before they lead to costly major repairs. Also, be able to recognize bridge elements that need repair in order to maintain bridge safety and avoid replacement costs.
The current funding available to rehabilitate and replace deficient bridges is not adequate to meet the needs. It is important that preservation activities be a part of the bridge program to extend the performance life of as many bridges as possible and minimize the need for costly repairs or replacement.
The engineer’s role is:
The inspector’s role is:
Subpart C of the National Bridge Inspection Standards (NBIS) of the Code of Federal Regulations, 23 Highways Part 650, mandates:
Bridge Inspection Programs are funded by public tax dollars. Therefore, the bridge inspector is financially responsible to the public.
The “Surface Transportation Act of 1978”established the funding mechanism for providing Federal funds for bridge replacement. The Act also established criteria for bridge inspections and requirements for compliance with the NBIS.
The “Intermodal Surface Transportation Efficiency Act” (ISTEA) of 1991 and the Transportation Equity Act for the 21st Century (TEA-21) of 1998 establish funding mechanisms for tolled and free bridges for bridge maintenance, rehabilitation and replacement to adequately preserve the bridges and their safety to any user.
The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) was signed into law in August 2005. SAFETEA-LU represents the largest surface transportation investment in the Nation’s history. SAFETEA-LU builds on and improves the initiatives established in ISTEA and TEA-21. Since being signed into law in August 2005, SAFETEA-LU has undergone several extensions past its original 2009 expiration, resulting in guaranteed funding until the end of Fiscal Year (FY) 2011. Multi-year legislation is expected to provide funding following FY 2011. Information on SAFETEA-LU can be found on the FHWA website:
http://www.fhwa.dot.gov/safetealu/factsheets/bridge.htm
There are three major reasons why accurate bridge records are required:
|
Year |
Abutment A |
Abutment B |
|---|---|---|
|
2011 |
4-3/16" |
3-1/2" |
|
2009 |
4-3/16" |
2-1/4" |
|
2007 |
4-1/8" |
1-1/8" |
|
2005 |
4" |
1" |
To ensure accurate bridge records, proper record keeping needs to be maintained. Develop a system to review bridge data and evaluate quality of bridge inspections. Bridge files are to be prepared as described in the AASHTO Manual for Bridge Evaluation. Record the findings and results of bridge inspections on standard State or Federal agency forms.
A bridge inspection report is a legal document. Make descriptions specific, detailed, quantitative (where possible), and complete. Do not use vague adjectives such as good, fair, poor, and general deterioration, without concise descriptions to back them up. To say “the bridge is OK” is just not good enough.
Example of inspection descriptions:
Bad description: “Fair beams”
Good description: “Reinforced concrete tee-beams are in fair condition with light scaling on bottom flanges of Beams B and D for their full length.”
Bad description: “Deck in poor condition”
Good description: “Deck in poor condition with spalls covering 50% of the top surface area of the deck as indicated indicated on field sketch, see Figure 42.”
Bad description: “The bridge is dangerous”
Good description: “Section loss exists on Girder G5 at 10 feet north of centerline of bearing at Pier 1. Original flange thickness 1.5 inches. Measured thickness 0.991 inches.”
Include phrases such as “no other apparent defects” or “no other defects observed” in any visual assessment.
Do not alter original inspection notes without consultation with the inspector who wrote the notes.
A bridge inspection report implies that the inspection was performed in accordance with the National Bridge Inspection Standards, unless specifically stated otherwise in the report. Use the proper equipment, methods, and qualified. If the inspection is a special or interim inspection, explained explicitly in the report.
The National Bridge Inspection Standards (NBIS) are regulations that were first established in 1971 to set national requirements regarding bridge inspection frequency, inspector qualifications, report formats, and inspection and rating procedures.
The NBIS can be found in the Code of Federal Regulations, Part 65, Title 23, Subpart C which is on the Bridge Technology site located on the FHWA website:
http://www.fhwa.dot.gov/bridge/nbis.htm
The NBIS set minimum, nationwide requirements. States and other owner agencies can establish additional or more stringent requirements.
The NBIS are very specific with regard to the qualifications of bridge inspectors. The Code of Federal Regulations, Title 23, Part 650, Subpart C, Section 650.309, (23 CFR 650.309), lists the qualifications of personnel for the National Bridge Inspection Standards (Appendix B of this Manual). These are minimum standards; therefore, state or local highway agencies can implement higher requirements.
The program manager is in charge of the organizational unit that has responsibility for bridge inspection, reporting, and inventory. The minimum qualifications are as follows:
The team leader is responsible for planning, preparing, and performing the inspections of individual bridges as well as the day-to-day aspects of the inspection. NBIS calls for a team leader to be present at all times during each initial, routine, in-depth, fracture critical and underwater inspection. There are five alternative ways to qualify as a team leader:
There are no specific federal guidelines for bridge inspectors. The main responsibility of a bridge inspector is to assist the team leader in day-to-day aspects of the inspection. Training is not required but it is recommended for non-team leaders. Any technical background is obtained through education and hands-on experience enables the inspector to successfully complete the tasks at hand. The goal is for the inspector to learn the correct inspection methods and to evaluate bridge components and elements consistently.
The dictionary defines tort as “a wrongful act for which a civil action lie except one involving a breach of contract.”
In the event of negligence in carrying out the basic responsibilities described above, an individual, including department heads, engineers, and inspectors, is subject to personal liability. Strive to be as objective and complete as possible. Accidents that result in litigation are generally related, but not necessarily limited, to the following:
Anything said or written in the bridge file could be used in litigation cases. In litigation involving a bridge, the inspection notes and reports may be used as evidence. A subjective report may have negative consequences for the highway agency involved in lawsuits involving bridges. The report scrutinized to determine if conditions are documented thoroughly and for the “proper” reasons. Therefore, be as objective and complete as possible. State if something could not be inspected and the reason it was not inspected.
Example of liabilities:
In a recent case, a consulting firm was found liable for negligent inspection practices. A tractor-trailer hit a large hole in a bridge deck, swerved, went through the bridge railing, and fell 30 feet to the ground. Ten years prior to the accident, the consulting firm had noted severe deterioration of the deck and had recommended tests to determine the need for replacement. Two years prior to the accident, their annual inspection report did not show the deterioration or recommend repairs. One year before the accident, inspectors from the consultant checked 345 bridges in five days, including the bridge on which the accident occurred. The court found that the consulting firm had been negligent in its inspection, and assessed the firm 75% of the ensuing settlement.
In another case, four cars drove into a hole 12 feet deep and 30 feet across during the night. Five people were killed and four were injured. The hole was the result of a collapse of a multi-plate arch. Six lawsuits were filed and, defendants included the county, the county engineer, the manufacturer, the supplier, and the consulting engineers who inspected the arch each year. The arch was built and backfilled, with mostly clay, by a county maintenance crew 16 years prior to the accident. Three years later, the county engineer found movement of three to four inches at one headwall. The manufacturer sent an inspector, who determined that the problem was backfill-related and recommended periodic measurements. These measurements were done once, but the arch was described as “in good condition” or “in good condition with housekeeping necessary” on subsequent inspections. Inspection reports documented a six inch gap between the steel plate and the headwall. A contractor examined the arch at the county engineer’s request to provide a proposal for shoring. The county engineer discussed the proposal with the consulting engineers a month before the accident. A total of 13 inspections were conducted on the structure. An engineering report accuses the county engineer of poor engineering practice.
The NBIS requires Quality Control (QC) and Quality Assurance (QA) procedures to maintain a high degree of accuracy and consistency in the highway bridge inspection program. Accuracy and consistency are important since the bridge inspection process is the foundation to the bridge management systems. FHWA has developed a recommended framework for a bridge inspection QC/QA program (see Topic 1.3).
Title 23, Code of Federal Regulations (CFR), Part 650, Subpart C, Section 313, paragraph (g), Quality Control and Quality Assurance, requires each state to assure that systematic Quality Control (QC) and Quality Assurance (QA) procedures are being used to maintain a high degree of accuracy and consistency in their inspection program. The FHWA has developed a recommended framework for a bridge inspection QC/QA program to assist bridge owners in developing their QC / QA programs.
Accuracy and consistency of the data is important since the bridge inspection process is the foundation of the entire bridge management operation and bridge management systems. Information obtained during the inspection is used for determining needed maintenance and repairs, for prioritizing rehabilitations and replacements, for allocating resources, and for evaluating and improving design for new bridges. The accuracy and consistency of the inspection and documentation is vital because it not only impacts programming and funding appropriations, it also affects public safety.
Quality Control (QC) is the establishment and enforcement of procedures that are intended to maintain the quality of the inspection at or above a specific level. If an inspection program is decentralized, the state program manager is still responsible for QC.
Quality Assurance (QA) isthe use of sampling and other measures to assure the adequacy of quality control procedures in order to verify or measure the quality level of the entire bridge inspection and load rating program. This is accomplished by the re-inspection of a sample of bridges by an independent inspection team. For decentralized state inspectionsor delegated inspection programs, the QA program can be performed by the central staff or their agent (e.g., consultants). If the inspections are centralized within the state, consultants or a division are to perform the QA program separate and independent of the inspection state organization.
The quality of the inspection and reports rests primarily with the inspection team leaders and team members and their knowledge and professionalism in developing a quality product. A QC/QA program is a means by which periodic and independent inspections, reviews, and evaluations are performed in order to provide feedback concerning the quality and uniformity of the state’s or agency’s inspection program. The feedback is then used to enhance the inspection program through improved inspection processes and procedures, training, and quality of the inspection report.
The FHWA has developed the following recommended framework for a bridge inspection QC/QA program.
Examples of Commendable State practices and additional resources regarding QC/QA programs are available at the following link: http://www.fhwa.dot.gov/bridge/nbis/nbisframework.cfm