The percentage of MDTA structurally deficient (SD) bridges within a given Calendar year.

Inspections are conducted every year on all MDTA facilities. Defects identified in yearly inspections are assigned a defect rating based on severity by the inspector. As a measure of quality assurance and control, the rating is reviewed and confirmed by in-house inspection staff during review of the inspection reports. The defects are prioritized based on the confirmed rating and major rehabilitation, total replacement or proactive system preservation projects are developed based on the priorities and overall condition assessment.

Bridges are considered structurally deficient if significant load carrying elements are found to be in a poor (or worse) condition due to deterioration and/or damage, or have a low weight restriction. The fact that a bridge is structurally deficient does not imply that it is unsafe. MDTA reported 5 structurally deficient bridges from the 2011 inspection cycle and four of these bridges are already in construction with the fifth in design for full replacement in 2014. The number of structurally deficient bridges is not anticipated to increase significantly over the next several years as MDTA continues to address needs using a bridge management system to identify and address those bridges that are nearing the end of their useful life.