Development of a "Manual" of Standard Practice for the Restoration Historic Bridges
Historic Preservation/Cultural Resources
Community & Cultural Concerns
Under 1 year
Research Idea Scope
Development of a “manual” of standard practice for restoring historic bridges would be of great help to the practicing engineer. Civil Engineering curriculum typically doesn’t teach in detail regarding wrought iron, early steels, early concrete, rivets, forged eye bar connections, stone bridge masonry, historic timber trusses, etc. This “manual” (developed and delivered as a WEB based tool to increase accessibility to the engineering community) should include, at a minimum, the following for each type of structure, such as a timber covered bridge, timber stringer bridge, steel truss, steel girder, concrete arch, concrete girders, concrete slabs, stone arches, stone piers, stone abutments: 1. Determination of material properties a. Wrought Iron b. Early steels c. Rivets d. Early bolts e. Early concrete f. Stone masonry g. Aged timber 2. Determination of structure condition a. Visual methods of evaluation (such as delamination surveys) b. Destructive methods of evaluation (such as concrete core compressive tests, steel sample tensile tests) c. Non-destructive testing such as the following: 1. Sonic Velocity Testing 2. Half-cell potential tests 3. Impact-Echo tests 4. Load tests / strain gauges 5. Petrograph Examinations 6. Liquid Penetrant 7. Ultrasonic testing 8. Ground penetrating radar 9. Radiography-X-ray 10. Magnetic Particle testing 11. Packometer 12. Infrared 3. Repair Methods Standard repair methods and case studies for: a. Steel and iron trusses b. Steel and iron girders c. Timber trusses d. Concrete arches e. Concrete girders f. Concrete slabs g. Stone arches h. Stone substructures such as piers and abutments Another area that needs to be addressed is the determination of foundation conditions when no plans for the original bridge are available. There are some geotechnical investigation techniques available that are non-destructive in nature. A discussion regarding these and when they should be applied would be of value to the engineering community. Ideally, this manual would combine material from existing sources and make it more widely available, but would also develop recommendations regarding gaps in information that need to be addressed by additional research. Existing guidance includes “GUIDELINES FOR HISTORIC BRIDGE REHABILITATION AND REPLACEMENT – AASHTO Standing Committee on the Environment” (Lichtenstein Consulting Engineers, Inc., March 2007), “Ohio Historic Bridge Maintenance & Preservation Guidance” (TranSystems, June 2010), “Repairing and Restoring Historic Bridges: Keeping Faith with Their Makers” (Indiana Landmarks), and “Restoring Historic Metal-Truss Bridges: A Handbook for Keeping Faith with Their Makers” (Indiana Landmarks). There are many other articles, case studies and research that have also been written in recent years regarding rehabilitation of historic structures. Information from these publications could be reviewed, condensed and organized according to various types of techniques and methods that can be applied to the restoration and rehabilitation of historic structures. An additional outcome of the development of this “Manual” would be the identification of areas that require additional research in order to provide adequate information for planning the rehabilitation of historic bridges.
Urgency and Payoff
In part, current research has been conducted by State DOTs, FHWA, consulting engineers, and interested preservation organizations in an effort to understand rehabilitation options for the ever decreasing number of Historic Bridges or in response to a specific historic bridge project. While many areas indicated in the scope have been researched in the past, much of the existing guidance is either not widely available, or is more process-oriented than technical. There is no comprehensive consolidation that is easily accessible, thus leading to redundant research efforts and cost. For example, one useful compilation would be a comprehensive list of “crash-tested” historically sensitive railings, thus avoiding the need for unnecessary testing by individual state DOTs. When asked about the value of this research, one consulting engineer responded: “If a manual could be developed to address [these issues], then it would be of great value to the engineering community when dealing with historic bridge structures. ” As the cultural resources represented by Historic Bridges continues to decrease nationwide and the DOT’s continue to face cost pressure; effective guidance on the restoration of these structures for continued use is crucial.
Paul Brandenburg Indiana Historic SPANs Taskforce 3173471004