Risk-Based Bridge Inspection Practices

2007

The aging of bridges and traffic volume increase result in deterioration of bridge conditions and consequently increased risks to bridges and users. Highway agencies in the United States face challenges because of lack of sufficient resources to maintain bridges in good conditions. Current bridge management practices use cost as the main factor for determining maintenance strategies for bridges. Bridge management methods that identify bridges based on risk considerations and produce cost-effective maintenance strategies are needed to best utilize limited resources for reducing risks associated with bridge conditions. This dissertation proposes and demonstrates a methodology for defining bridge maintenance strategies based on risks associated with conditions of bridge elements and costs needed to improve these conditions. The methodology is a systematic approach for assessing risks to bridge elements based on their failure probabilities and consequences and managing associated risks using cost-effective maintenance strategies. The proposed methodology defines maintenance scenarios, optimal policies that minimize cost of maintenance and risks to elements, and optimal timing for implementing or deferring maintenance policies. The element-level maintenance policies in the proposed methodology are integrated with bridge-level priority ranking to define practical maintenance strategies for an inventory of bridges. The bridges are prioritized for maintenance according to their risk values and risk-reduction effectiveness of their maintenance policies based on benefit-cost analysis. The proposed methodology builds on existing bridge management methods, and allows for the use of risks associated with bridge conditions to assist in making risk-informed decisions for allocating limited resources for cost-effective maintenance strategies of bridges most in need. The study showed that risk is a viable tool for managing the maintenance of bridges in a cost-effective manner. The case study showed that the proposed methodology is feasible and can be implemented in currently used bridge management systems.

Transportation Research Record, 2001

Routine inspection is the most common type of highway bridge inspection completed to satisfy the requirements of the National Bridge Inspection Standards. Routine inspections of highway bridges are typically completed using only visual inspection (VI) and rely heavily on subjective assessments made by bridge inspectors. Given this practice and the fact that VI may have limitations that affect its reliability, the Federal Highway Administration completed a comprehensive study to examine the reliability of VI as it is currently practiced in the United States. The accuracy and reliability of condition ratings generated through routine inspections of six in-service and decommissioned highway bridges were studied. These timed inspections were completed in normal summer weather conditions under direct observation. To ensure that results from this study would be applicable to normal bridge inspections, state department of transportation bridge inspectors made up the study sample, which included 49 inspectors from 25 states, representing a diverse cross section of the bridge inspector population. Results of the study indicate that routine inspections are completed with significant variability. Specifically, 95 percent of primary bridge element condition ratings will vary within two rating points of the average, and only 68 percent of these ratings will vary within one rating point. Additionally, the National Bridge Inspection Standards definitions of condition rating may not be sufficiently refined to allow for reliable routine inspection results.

Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2011, San Diego, USA, March 6-10, 2011, pp. 79830K1-13, doi: 10.1117/12.880336, doi: 10.1117/12.880336, 2011

Bridges are critical to the operation and functionality of the whole road networks. It is therefore essential that specific data is collected regarding bridge asset condition and performance, as this allows proactive management of the assets and associated risks and more accurate short and long term financial planning. This paper proposes and discusses a strategy for collection of data on bridge condition and performance. Recognizing that risk management is the primary driver of asset management, the proposed strategy prioritizes bridges for levels of data collection including core, intermediate and advanced. Individual bridges are seen as parts of wider networks and bridge risk and criticality assessment emphasizes bridge failure or underperformance risk in the network context. The paper demonstrates how more reliable and detailed data can assist in managing network and bridge risks and provides a rationale for application of higher data collection levels for bridges characterized by higher risk and criticality. As the bridge risk and/or criticality increases planned and proactive integration of structural health monitoring (SHM) data into asset management is outlined. An example of bridge prioritization for data collection using several bridges taken from a national highway network is provided using an existing risk and criticality scoring methodology. The paper concludes with a discussion on the role of SHM in data collection for bridge asset management and where SHM can make the largest impacts.

Maintaining, repairing and rehabilitating Illinois' more than 8,000 bridges in a cost effective manner is critically dependent on reliable inspection and condition assessment data. In the past few years advances in non-destructive testing and inspection data acquisition in the field promise to improve the process considerably. This project explored these advances through a literature review, interviews, surveys, field observations and field-testing. Following extensive interviews and field visits with bridge inspectors and bridge maintenance engineers in Illinois, a survey was distributed to other state Departments of Transportation. The survey identified states using new technologies for data acquisition and visits were arranged to Maryland, Montana, New York and Pennsylvania. Based on the field input and observations in the field, the concept of field data entry and upgraded data acquisition equipment looks the most promising for Illinois. A prototype data acquisition was developed to mimic the current process. Limited field testing met with positive responses. In addition to obtaining new updated equipment, software and training will also be required. The inspection support systems explored in this project are just the preliminary steps in the process of electronically collecting and recording information for IDOT bridge inspections. The procedure can be further developed and simplified in the future as the technology advances. Specific issues include report generation, pen-based application, voice recognition and the development of a web application.

Twenty four years of historical National Bridge Inventory (NBI) data for deck and superstructure component condition ratings were examined using a methodology that isolates condition improvements caused by maintenance. Significant maintenance actions are revealed in the historical NBI record as condition improvements. Using certain assumptions the effects of maintenance have been isolated to avoid eliminating such records from a time-in-condition analysis to enable an empirical investigation of bridge deterioration. The data analysis utilizes a time-based model using the survival of a bridge component’s condition for a specific time period. New variables are constructed to track continuous time-in condition and to monitor how the condition changes over time, either improving due to maintenance or deteriorating. Selected bridge characteristics that are believed to influence bridge performance are investigated independently to gauge their potential influence on survivability. Characte...

2012

U.S. engineers need advanced tools and protocols to better assess and assure safety and serviceability of bridges. The Federal Highway Administration, American Association of State Highway and Transportation Officials, and National Cooperative Highway Research Program sponsored a scanning study of Europe to identify best practices and processes to assure bridge safety and serviceability. The scan team found that the European highway agencies expect their bridge programs to not only ensure user safety, but also to meet serviceability expectations and enhance capital investment decisions. The team gathered information on safety and serviceability practices and technologies related to design, construction, and operations. Team recommendations for U.S. implementation include developing a national strategy to increase use of refined analysis for bridge design and evaluation, encouraging States to use refined analysis combined with reliability analysis to avoid unnecessary rehabilitation or replacement of bridges, and encouraging adoption of the concept of annual probability of failure to quantify safety in probability-based design and rating specifications.

In order to make management decisions on the bridge operation effective, it is needed to have reliable information about bridge technical state. Obtaining qualitative and quantitative indicators of bridge operational properties is achieved by bridge inspection and further processing of bridge inspection results by calculations and expertizing. A bridge inspection is an important part of bridge life cycle, its results make it possible to plan the effective use of funds for bridge maintenance and therefore considerable attention should be given to this type of work. A timely bridge inspection makes it possible to ensure reliable and trouble-free bridge maintenance. The best practices show that the cost of the bridge inspection is repaid by optimizing the cost of bridge maintenance. Only in the case of a comprehensive timely assessment of the bridge state and timely implementation of repair works, effective bridge maintenance is possible. The paper considers the regulatory framework on the requirements for the bridge inspection, including classification and frequency, etc. A detailed analysis of implementation of bridge inspections on public roads of Ukraine is conducted. Information on bridge inspections is collected and accumulated in a common database, in the software Analytical Expert Bridge Management System (AESUM). AESUM database has been used in Ukraine since 2006 and contains 16 141 bridges on public roads, including 5 820 bridges on state roads and 10 321 bridges on local roads. About 76% of bridges on state roads and only about 15% on local roads have been inspected so far. The analysis showed that the normative bridge inspection interval is mostly not maintained. Therefore, the paper proposes a number of criteria for prioritizing while making plans for bridge inspection. The detailed justification of the offered criteria is carried out. The analysis was performed mainly by tools developed within the individual modules of the AESUM software.

2015

Bridges play a vital role in road infrastructure networks. According to Statistics Canada, bridges and overpasses accounted for 8% of total public assets in 2007.. Ontario ranked as the third among provinces in terms of having old bridges. In 2007, Bridges in Ontario accounted for 7% of its public infrastructure, while in Alberta, bridges account for 9% of total public infrastructure. Bridge condition assessment is conducted to determine load rating capacity for bridge elements. The identification of current condition of each element provides early warning of necessary maintenance. Condition rating is performed during the inspection process. This paper provides a comparative study of current practices in bridge condition rating worldwide, with emphasis on the United States and Canada. The study includes 4 main criteria: inspection levels, inspection principles, inspection frequencies and numerical ratings for 4 provinces in North America: Alberta, Ontario, Quebec and state of Oregon and 5 countries outside North America: United Kingdom, Denmark, Portugal, Sweden and Australia. The Limitations of current practices are discussed and recommendations for improved inspection are provided. The study is expected to assist professionals and inspectors in selecting feasible method/s for effective bridge condition assessment.

2003

Bridge management systems have become increasingly sophisticated over the past decade and provide valuable information about the structural condition of all bridges in the national database. At the same time, reliability methods have gained increasing prominence and are used to forecast life-cycle performance over many decades of structural life. Such reliability analyses need to be updated based on the results of inspections. Specifically targeted nondestructive evaluations are the preferred solution, but are not always available for every bridge. This paper examines how the visual inspection data provided from bridge management systems already in place can be used to update the reliability of a bridge. The limitations and necessary modifications to current practice are discussed. The superstructure of a Colorado highway bridge deteriorating due to corrosion is used as an example.

A recent project by Cork County Council has allowed the compilation and analysis of detailed inventory and inspection data of 1,400 bridges on its regional and local road network. Each bridge and its constituent components or elements have been visually inspected and their structural condition rated based on a defined scale of deterioration and damage. This paper presents data on bridge structure type and geometry as well as condition ratings for each bridge component. The worst performing bridge components and the most recurrent damage types are identified. Conclusions are drawn on the overall condition of the bridge stock, the critical structural components and the deterioration mechanisms that impact upon them.