"Poor" Rated Bridges

"Poor" Rated Bridges on the Maryland State Highway System

The poor rating is an early warning sign for engineers to prioritize funding and initiate preservation and/or rehabilitation efforts or to replace the bridge.

The rating applies to three main elements of a bridge:

  1. The deck (riding surface).
  2. The superstructure (main supporting element of the deck, usually beams, girders, and trusses).
  3. The substructure (supports to hold up the superstructure and deck - usually abutments and piers).

These elements are rated on a scale from zero (closed to traffic) to nine (relatively new). If any of the three elements is rated as a four or less, the bridge is categorized as being in poor condition by federal regulations.


This does not mean that the bridge is unsafe.

If a bridge becomes unsafe, it will be closed.

The summary below is from the annual MDOT SHA submission to the Federal Highway Administration (FHWA) made in March 2021. It reports that there are 2555 bridges on the Maryland State Highway System, of which 29, or about 1%, are rated as poor. The number of “poor” rated bridges decreased from 143 in 2006 to 29 in 2021.

Summary for 2021
Number of bridges rated poor on March 15, 202038
Number of "poor" rated bridges addressed in 202012
Number of bridges which were rated poor in 20213
Total number of structurally deficient bridges on March 15, 2021

Prior to 2018, FHWA used the term “Structurally Deficient” to identify bridges rated as poor. FHWA no longer uses this designation. The structurally deficient rating is like the poor rating, as it included bridges where one of the main elements are rated four or less, but also included criteria involving a bridge’s structural load carrying capacity and hydraulic adequacy.