Selection of Bridges for Mid-Atlantic Prestressed Concrete and Steel Multi-Girder Bridge Clusters

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The Federal Highway Administration’s (FHWA’s) Office of Infrastructure Research and Development (HRDI) would like to announce the selection of the first 24 bridges in the Mid-Atlantic region of the United States that will be included in initial field investigations of untreated concrete bridge decks as part of the FHWA’s Long-Term Bridge Performance (LTBP) Program – a research study managed by HRDI staff that aims at identifying how bridges perform and why they perform the way they do.  These initial field investigations will focus on prestressed concrete and steel multi-girder bridge clusters within the Mid-Atlantic region. Untreated bridge decks were previously identified through stakeholder input as one of the highest priority bridge performance issues to be investigated through this study.  A list of the high-priority bridge performance issues is presented in Table 1.  We would like to emphasize that based on available resources the initial efforts of long-term data collection are focused on gaining a better understanding of the performance of untreated bridge decks.

The selection process for bridges with untreated concrete decks in the aforementioned clusters was accomplished by first meeting with and providing each bridge owner within the Mid-Atlantic region a list of candidate bridges for possible inclusion in LTBP field studies.  Based upon local expertise, each owner prioritized the candidate bridges (high, medium, low) with respect to importance for inclusion in the study, site accessibility, plans for future rehabilitation or replacement, and traffic control needs and then provided their prioritization to FHWA.  Upon receipt of candidate bridge prioritization from all owners involved in the Mid-Atlantic clusters, a rigorous statistical analysis was undertaken to ensure adequate distribution of experimental parameters for the final selection of bridges to include in each cluster.  For more detailed information on the selection process, experimental parameters, and the experimental design of field studies, please visit the FHWA’s LTBP website at https://www.fhwa.dot.gov/multimedia/research/infrastructure/bridges/ltbp/index.cfm.

The map presented in Figure 1 shows the approximate location of the 24 bridges selected from the steel and prestressed concrete multi-girder clusters within the Mid-Atlantic region.  The map includes 4 reference bridges, e.g., bridges that will receive detailed inspection using both visual observation as well as advanced NDE technologies.  The remaining 20 bridges will undergo detailed visual inspection and limited application of NDE technologies. The steel multi-girder cluster bridges are indicated by orange locations with the 2 orange pushpins indicating steel reference bridges, while the prestressed concrete multi-girder cluster bridges are indicated by blue locations with the 2 blue pushpins indicating prestressed concrete multi-girder reference bridges.

Figure 1 – Map showing location of steel (orange) and prestressed concrete multi-girder (blue) bridges for the Mid-Atlantic steel and prestressed concrete multi-girder clusters.

Each of the selected steel and prestressed concrete multi-girder cluster bridges within the Mid-Atlantic region presented in Figure 1 is also presented in Table 2 along with the appropriate state and structure number.

We would like to emphasize that this initial selection of bridges is pending verification through site visits and collection of initial documentation for each bridge.  In addition to the selection of reference and cluster bridges for the Mid-Atlantic region’s prestressed concrete and steel multi-girder bridges, a tentative field testing schedule has also been developed (see Table 3).  Although this tentative schedule is very aggressive, initial field evaluation of each bridge is planned to be completed by early fall 2013.  This tentative schedule is subject to review and approval by each individual bridge owner and is subject to weather conditions.  Our LTBP contractor will be contacting individual states to confirm test dates as appropriate.   Also, our LTBP contractor is currently contacting each owner to initiate the process of gathering documentation for each bridge for further study and verification purposes.  We would like to highlight that 2 of the 24 structures selected for initiation of long-term monitoring in the Mid-Atlantic region have already been inspected and results of those inspections are currently being evaluated.

Bridges in the District of Columbia have not been selected for this portion of the LTBP study as they typically contain some form of deck treatment, and therefore, will be included in the treated deck portion of the LTBP study.

In addition to the selection of cluster and reference bridges in the Mid-Atlantic region, the bridge selection for several additional bridge clusters in Gulf, Pacific Northwest and Southwest regions is underway.  We anticipate that initial reference and cluster bridge selections within these regions will be announced in early fall 2013.  Each of these bridge clusters as well as the Mid-Atlantic clusters is shown in Figure 2.

Figure 2 – Map showing location of Mid-Atlantic, Gulf, Pacific Northwest, and Pacific Southwest clusters.

For questions or additional information please contact Robert Zobel by telephone at 202-493-3024 or email at robert.zobel@dot.gov or visit the LTBP website at https://www.fhwa.dot.gov/research/tfhrc/programs/infrastructure/structures/ltbp/index.cfm