Forest Products Laboratory General United States Department of Agriculture Technical Forest Service Report FPL–GTR–223 In cooperation Covered Bridge with the United States Department of Security Manual Transportation Brent Phares Federal Highway Terry Wipf Administration Ryan Sievers Travis Hosteng Abstract Contents The design, construction, and use of covered timber bridges Introduction .........................................................................1 is all but a lost art in these days of pre-stressed concrete, high-performance steel, and the significant growth both in Overview—Covered Bridge Surveillance Project, the volume and size of vehicles. Furthermore, many of the Iowa State University ..........................................................1 existing covered timber bridges are preserved only because Literature Review ................................................................2 of their status on the National Registry of Historic Places or the diligent maintenance and care of the owners of these Covered Bridge Monitoring System: Design ......................5 structures, or both. Of the covered timber bridges that Set-Up ...............................................................................17 remain in the United States, only a small percentage still stand today because of arson, vandalism, neglect, natural Testing ...............................................................................19 disasters, and other factors. The objective of this work is Summary ...........................................................................20 to provide covered timber bridge owners with the tools to quickly and efficiently design and implement a security Recommendations .............................................................20 system to protect these important historical landmarks. This Madison County Project ...................................................21 goal was obtained with an in-depth analysis of equipment based on the practicality in a covered bridge application. Challenges with Each Bridge ............................................24 Other major considerations required for all equipment to Testing ...............................................................................29 work efficiently within a security system are also fully discussed, including, but not limited to, maintenance, power Example Case Studies .......................................................29 requirements, and general set-up of an integrated security Real Case Studies ..............................................................31 system. A comprehensive case study is presented involv- ing monitoring systems placed on five of the six covered References .........................................................................33 bridges in Madison County, Iowa, at the end of this report to showcase the abilities of an integrated system and all the This study is part of the Research, Technology and Educa- decisions that must be made throughout the process for the tion portion of the National Historic Covered Bridge entire system to work as intended. Preservation (NHCBP) Program administered by the Keywords: Covered bridges, wood bridges, security Federal Highway Administration. The NHCBP program includes preservation, rehabilitation and restoration of covered bridges that are listed or are eligible for listing on the National Register of Historic Places; research for better means of restoring, and protecting these bridges; development of educational aids; and technology transfer May 2013 to disseminate information on covered bridges in order to Phares, Brent; Wipf, Terry; Sievers, Ryan; Hosteng, Travis. 2013. Covered preserve the Nation’s cultural heritage. bridge security manual. General Technical Report FPL-GTR-223. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Labo- ratory. 34 p. A limited number of free copies of this publication are available to the This study is conducted under a joint agreement between public from the Forest Products Laboratory, One Gifford Pinchot Drive, the Federal Highway Administration–Turner Madison, WI 53726–2398. This publication is also available online at www.fpl.fs.fed.us. Laboratory publications are sent to hundreds of libraries Fairbank Highway Research Center, in the United States and elsewhere. and the Forest Service – Forest Products Laboratory. The Forest Products Laboratory is maintained in cooperation with the University of Wisconsin. Federal Highway Administration Program Manager– The use of trade or firm names in this publication is for reader information Sheila Rimal Duwadi, P.E. and does not imply endorsement by the United States Department of Agriculture (USDA) of any product or service. Forest Products Laboratory Program Manager– Michael A. Ritter, P.E. The USDA prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orienta- tion, genetic information, political beliefs, reprisal, or because all or a part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program informa- tion (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720–2600 (voice and TDD). To file a complaint of discrimi- nation, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250–9410, or call (800) 795–3272 (voice) or (202) 720–6382 (TDD). USDA is an equal opportunity provider and employer. Covered Bridge Security Manual Principal Investigator Brent Phares Co-Director, National Center for Wood Transportation Structures Institute for Transportation, Iowa State University Co-Principal Investigator Terry Wipf Co-Director, National Center for Wood Transportation Structures Institute for Transportation, Iowa State University Research Assistant Ryan Sievers Travis Hosteng Bridge Research Specialist, Bridge Engineering Center Institute for Transportation, Iowa State University Introduction purpose of heightening security. Because very little techni- cal literature exists dealing exclusively with the subject of Covered bridges used to cover the American landscape from security and monitoring systems for covered bridges, we coast to coast. However, because of various factors includ- contacted multiple Departments of Transportation (DOTs) ing neglect, arson, vandalism, and natural disasters, current- with a high concentration of covered bridges as well as ly less than 700 to 900 bridges are still in existence today. multiple bridge owners to assess the state of covered bridge Covered bridges tend to be in isolated areas, and they are security in the United States. This insight from bridge own- constructed with a flammable material, which makes them ers coupled with technical literature about physical security highly susceptible to arson and vandalism. Because they are of other assets is the basis of this report. usually far from populated areas, it is difficult for firefight- ers to arrive at the bridges in a timely manner once a fire has Overview—Covered Bridge been set. This makes it likely that any fire may cause critical Surveillance Project, Iowa State damage or may completely destroy a bridge. Most of these covered bridges are covered by volunteer fire departments, University which only adds another level of complexity to the situation. In 2005, the Bridge Engineering Center (BEC) at Iowa State It is essential that we protect and preserve these standing University (ISU) completed a case study on remote security landmarks throughout our country for future generations. of historic covered bridges by designing and implementing One way to provide the necessary security is to use remote an active monitoring system on the Cedar Covered Bridge in monitoring and other security systems to protect them from Madison County, Iowa (Phares 2006). The security system trespassers. installed on the Cedar Bridge is discussed further in the case Multiple bridge owners throughout the United States have studies portion of this report. The work completed and the taken measures to ensure the safety and integrity of their system developed for the Cedar Bridge resulted in the BEC covered bridges by implementing structural strengthening, receiving a grant from the Federal Highway Administration fireproofing, and monitoring systems. Common protective (FHWA), through the National Historic Covered Bridge methods entail illuminating the bridge site and using fire- Preservation Program (Matias 2011), to install remotely retardant material around important structural members. monitored security systems on the other five covered bridges These methods are typically used because they are usually in Madison County. The five bridges included in the security very cost effective. Unfortunately, these systems are passive monitoring grant, the Cutler–Donahoe, Holliwell, Hogback, approaches and provide no mechanisms to alert the proper Imes, and Roseman covered bridges, are five of the six land- authorities and increase the chances of survival for the mark bridges that remain in Madison County and the only bridges. bridges that have not been completely rebuilt. The Hogback Bridge was partially damaged by arson but managed to sur- This report is intended to assist covered bridge owners in vive and was restored