Risk-Based Bridge Evaluations — A Texas Perspective

The Texas Department of Transportation (TxDOT) has performed fracture critical inspections since 1990 using hands-on inspection methods. Up until 2005 TxDOT had used a risk based criteria that was approved by the Federal Highway Administration to set fracture critical inspection frequencies from 6 months to 60 months. It was felt that this methodology would allow the department to properly manage any risks associated with fracture critical structures and maximize the return on highway dollars. Since 2005 TxDOT has been inspecting fracture critical bridges at the frequency as mandated in the Code of Federal Regulations of 24 months. The state of the art for fabrication and design has come along way since the original concept of fracture critical inspections was proposed. Mandating rigid inspection schedules independent of magnitude of service stresses, age of the structure, material improvements, implementation of fatigue resistant details, better fabrication practices, and frequency of the loading cycles on a bridge is not a cost effective method for obtaining the desired safety. Other countries use risk based criteria to determine inspection frequencies for their bridge inventory. While TxDOT no longer uses a risk based approach to set fracture critical inspection frequencies work is still being done to show that risk based inspection frequencies are a valid and safe method for establishing evaluation frequencies.