U.S. Department of Transportation
Federal Highway Administration
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Team members identified a number of bridge inspection initiatives or practices that varied from those in the United States in some respect. The team recommended that six of these initiatives or practices be further considered for study and possible implementation in the United States.
The six initiatives and practices the scan team identified are as follows:
Each implementation topic has specific actions to enable the utilization of scan results within the context of existing bridge evaluation and inspection programs in the United States, with an emphasis on improving quality control and quality assurance practices.
All of the countries the team visited had clear definitions of inspection types. A major finding was that each country also has several well-defined scopes for its inspections. A typical finding was that most European agencies have developed a technical decisionmaking process for determining inspection frequency. This process considers the scope of the inspection to be conducted and identifies training and qualification requirements for inspectors. Generally, this consisted of comprehensive inspections at intervals of up to 6 years or more, with inspections of the lesser scope used more frequently.
The scan team recommends the development of a nationally accepted basis for determining bridge inspection frequencies based on factors such as safety, condition, design, age of the structure, and engineering judgment. Different levels of inspection intensity and scope should be combined with clear standards for inspector education, training, and qualification. Combining different levels of inspection with more comprehensive and indepth inspections at 6 years or other suitable frequency and inspections with a more limited scope at shorter intervals may provide more effective inspections, improve overall quality, and allow more effective use of resources. This could be implemented as an optional tool that a State or Federal agency could use for newer bridges, or it may be suitable for implementation on a wider scale. Ultimate implementation of the process will likely require FHWA to modify the National Bridge Inspection Standards (NBIS) regulation.
The implementation strategy includes review and modification of a problem statement under development entitled "Developing Reliability-Based Bridge Inspection Policies," which provides a basis for study of the concepts and processes identified by the scan team. It also includes working with AASHTO, FHWA, TRB, and others to ensure approval and funding of the proposed project. Based on the recommendations of the project, AASHTO, working with FHWA, should develop proposed revisions to the current NBIS along with supporting references and National Highway Institute training modules.
The scan team recommends the development of national guidelines for developing QC/QA procedures for use by State and local agencies. These guidelines would be for in-house staff and similar guidelines could be made part of bridge inspection services contracts. To develop these guidelines, it is suggested that a State DOT technical panel work in conjunction with a technical resource within the NCHRP framework to develop practical, implementable guidance that extends the existing FHWA framework. Clear descriptions of how to apply these guidelines within the context of an individual State inspection system will be required. Documentation and practices from other industries, such as the ISO 9001 process and other applicable documents, should be reviewed and implemented if practicable, as well as existing research (e.g., ongoing NCHRP Synthesis Topic 37-05 on bridge inspection practices). Consideration of the reference bridge concepts and development of statistically based methods for measuring uniformity of bridge inspections (based on the Finnra model) should be considered, as well as an examination of reference photographs for use as a tool in a QA/QC program. Establishing a pilot program in one or more States may be appropriate. Funding sources for such a study may include FHWA, State DOTs, University Transportation Centers (UTCs), or NCHRP.
The implementation strategy includes development of an NCHRP 20-07 Problem Statement, "Guideline for Implementing Quality Control and Quality Assurance for Bridge Inspection," to provide for the development of guidelines as described above and working with AASHTO, FHWA, TRB , and others on transferring the guidelines into practice in the States.
Many detailed, heavily illustrated manuals and references were available as tools for bridge inspectors in many of the countries visited. These included inspection manuals, maintenance guides, repair manuals, and coding and recording data guides. The primary approach in the United States and the European countries the scan team visited is visually based inspection. The Europeans use visual aids to a greater extent in the recording and coding of data, damage assessment, and maintenance and repair. Many more manuals appeared to be readily available to inspectors than is typical in the United States. To focus inspectors and provide more uniform ratings, the types of damage with performance indices were clarified by accompanying photographs. These manuals contained many photos and drawings showing the damage and its corresponding rating levels.
The scan team recommends the expanded use of illustrations and reference photographs describing bridge conditions to improve accuracy and consistency of inspections. To support this recommendation, the scan team will survey FHWA Divisions to determine which States have photos and illustrations in their inspection manuals.
In addition, the scan team suggests that a study team be organized to frame the initiative and develop an approach to move toward expanded use of illustrations and reference documentation. The objectives of the study team will include the following:
The ultimate goal of implementation is to define a longer term project by FHWA or NCHRP to develop improved inspection resources, and implement photos and illustrations as tools for highway bridge inspection ratings across the country.
The implementation strategy includes developing an illustrated manual survey requesting information on State use of illustrations and photos to improve accuracy and consistency in bridge inspection and distributing the questionnaire to the FHWA Division offices. Upon completion of the survey, organize a group of subject matter experts from FHWA, AASHTO, academia, and the private sector to identify best practices and incorporate them into FHWA bridge inspection manuals and guides.
Most of the European agencies visited include a cause of damage investigation by the inspector as part of their bridge inspection procedure. Inspectors are trained to assess damage to a structural element based on structural stability, user safety, and effect on the damaged component's durability. In many cases, inspectors were also charged with developing recommended corrective action to address the damage and evaluating the urgency of the repair need. Using the inspector's knowledge of structures and determination of urgency, an agency can calculate the immediate and short-term programming levels required.
The scan team observed a greater emphasis in Europe on determining the cause of deterioration or damage in the structure as part of the inspection process. This is in contrast to the U.S. approach of characterizing the element or component (i.e., rating the component), which essentially characterizes the effect of the damage but does not characterize its cause. Characterizing the cause of the deterioration during the inspection process may provide a better integration of mitigation strategies (i.e., repair and rehabilitation activities specified by the inspector).
Possible implementation actions include exploring the development of a manual that provides an array of recommended repairs linked to specific inspection conditions. Such a manual could be used for improving inspector training and improving inspection and maintenance of structures. A model for such a manual was observed in Finland, where the SILKO manual helps inspectors recognize the mechanisms behind observed damage and understand appropriate repair procedures. Such a manual would assist in developing a link between inspection rating and repair activities. An examination of how the AASHTO CoRe Element Manual could be used to achieve these objectives should be conducted.
Other implementation actions are recommended that could assist more generally in providing better tools for inspectors to assess the condition of bridges and integrate inspection and repair strategies. These include broader implementation of nondestructive evaluation (NDE) within the context of routine bridge inspections. Reintroduction of the National Highway Institute (NHI) training course on NDE for highway bridges should be explored. Also, scan team members should support the Structural Materials Technology: NDE for Highways and Bridges Conference to be held in Oakland, CA, in December 2008. This conference will include a workshop on NDE technologies for routine inspections.
The implementation strategy includes supporting the development of integrated inspection repair approaches and translation and dissemination of the SILKO manual, as well as other references and manuals discovered during the scanning tour and referenced in the final report. Also, FHWA and AASHTO should explore and support reintroduction of the NHI course on NDE for highway bridges, and support the Structural Materials Technology conference planned for 2008.
A number of interesting and valuable items were discovered during the course of the scanning study that are appropriate for technology transfer activities in the United States. Many of these items are highlighted elsewhere in the report. Of particular interest are the following:
Also, the scan team observed that Finland in particular was implementing some innovative QA/QC activities. Additional technical interchange with representatives of Finnra is recommended.
The implementation strategy includes development by FHWA of a reference Web site for scan data and recommendations. Included on this site should be the NDT compendium and other documents of interest discovered during the scanning study.
An ultrasonic shear wave transducer that enables the acoustic imaging of embedded features in concrete structures was demonstrated during the scanning study. This technology, developed and manufactured in Russia, has not been available in the United States. This technology has potential for application in the United States under several scenarios, including the detection of grout voids in post-tensioning ducts, as well as more traditional acoustic wave applications such as pulse velocity and delamination detection. A pilot or demonstration project could assist in transferring this technology to the United States.
The implementation strategy includes encouraging development of an NCHRP IDEA project or a State DOT-funded project to demonstrate this technology in the United States. Technology transfer activities to support the development of a project to demonstrate this technology in the United States should be undertaken.
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