Use of NDT Technologies in US Bridge Inspection Practice

Abstract

Bridge Inspection Bridge has evolved considerably, through legislation and regulations, since the early twentieth century when it used to account for a relatively small portion of the maintenance work done by states and others. The origins of current bridge inspec- tion practices can be traced to the collapse of the Ohio River Bridge (known as the Silver Bridge) between Point Pleasant, West Virginia and Kanauga, Ohio, which killed 46 people. President Johnson, responding to this tragedy, initiated a task force to determine the cause of the collapse and determine procedures to avoid future disasters such as this. The work of this committee resulted in a March 1968 memorandum to the states to review and inventory all existing highway structures by January 1970 to ensure public safety. The Federal Highway Act of 1968 led to the establishment of the National Bridge Inspection Standards (NBIS), which include frequencies and quali- 1 These inspections, in accordance with NBIS, led to a complete structural inventory and correction of most serious problems. It has also led to systematic periodic inspections by qualified personnel and is the basis for the current NBIS. The NBIS has been modified several times, including after the failure of the Mianus River Bridge in Greenwich, Connecticut and the Schoharie Creek Bridge near Fort Hunter, New York, which led to fracture- critical and underwater bridge inspections with established intervals. In bridge management terminology, the term inspection refers to (field) visual of structures, which is equivalent to visual testing as used by ASNT. The word testing mostly refers to the use of NDT methods such as MT, PT and UT, as well as to static and dynamic load testing.