Retrofit Railings for Historic Metal Truss Bridges

The Texas Department of Transportation (TxDOT) Environmental Affairs Division has developed a bridge project coordination process to ensure that bridge replacement projects comply with preservation laws and regulations and to facilitate project coordination with the State Historic Preservation Officer (SHPO). From this process, the TxDOT Historic Bridge Task Force was formed in 1996 for the purpose of developing a methodology to evaluate preservation options for on-system truss bridges that are listed or are eligible for listing in the National Register of Historic Places. Section 106 of the National Historic Preservation Act of 1966, as amended, requires TxDOT, acting as an agent for the Federal Highway Administration (FHWA), to coordinate all federally funded, licensed, or permitted bridge projects involving bridges 50 years of age or older with the staff of the SHPO. In Texas, the SHPO is the Executive Director of the Texas Historic Commission. In 2003, there were 38 metal truss bridges 50 years of age or older remaining on the State of Texas highway system. Of these 38 bridges, 33 are listed in the National Register of Historic Places. Many of these bridges do not meet current design criteria for rehabilitation because they have narrow deck widths, low vertical clearance, and substandard load capacity. In addition, the existing bridge railing systems on these bridges have not been shown to meet the current requirements for safety and strength.