The National Bridge Inspection Standards (NBIS) define complex bridges as movable, suspension, cable stayed, and other bridges with unusual characteristics. The AASHTO Manual for Bridge Evaluation (MBE), Section 4.9 Special Structures, provides guidance on bridge inspection requirements for special structure types such as movable bridges, suspension bridges, cable stayed bridges. These are some examples of structure types considered to be complex bridges. By definition, complex bridges are structure types with unusual characteristics.
Complex bridges are usually subject to specialized inspection procedures, additional inspector training and experience may be required to inspect complex bridges. Under the NBIS regulations, states are required to identify complex structures, develop the inspection procedures, and inspector training and experience requirements for these structures. Complex bridges are inspected according to those procedures. Complex bridge inspection requirements, procedures, and inspector qualifications are usually contained in the Bridge Inspection Manuals published by the owner or in their state regulations. Due to the limited guidance in the MBE and NBIS, owners have developed their own complex bridge inspection program requirements to fill this need and meet the NBIS requirements. This results in wide variability among the procedures with respect to the level of detail, inspection rigor, and training requirements.
A complex bridge is a bridge that because of its intricacy may require a significantly
greater inspection effort than could be accomplished on a normal routine inspection. These inspections require greater engineering knowledge and/or expertise to accurately and fully determine the condition of the various bridge elements. They also may require specialized equipment or climbing to access all parts of the bridge.
There is an immediate need for additional guidance on complex bridge inspections. CFR 650.313 (f) – requires that agencies have specialized inspection procedures, and additional inspector training and experience required to inspect complex bridges. Instead of each state developing their own procedures for these types of bridges, it would be best to develop general procedures that can be used by all the states.
The objective of this research is to develop guidelines for complex bridge inspection to support State DOTs in preparing their own complex bridge inspection procedures that will comply with Metric 19 of FHWA’s 23 Metrics. The proposed guidelines with commentary are intended to be incorporated into the Section 4 of the AASHTO Manual for Bridge Evaluation or be presented as a stand-alone supplement to the AASHTO Manual for Bridge Evaluation.
Agency final report was submitted to AASHTO Technical Committee on Bridge Management, Evaluation, and Rehabilitation (T-18). (NCHRP Staff: W. Dekelbab)