While transportation officials ordered the immediate inspection of 27 bridges last week after concrete fell from a Prince George's County overpass, Maryland has dozens of other spans similarly designated as structurally deficient.
Those 27 bridges were targeted because they were of similar age and condition to the Capital Beltway bridge that is now under repair after concrete fell from its underside onto a car driving on Suitland Road in Morningside.
That bridge was considered structurally deficient by the State Highway Administration. In addition to those ordered inspected last week, there are more than 50 other bridges with that designation, according to the administration's most recent report, dated April 2014.
A bridge rated structurally deficient is given priority for funds to repair or replace it.
The highway administration said Saturday that it completed inspections of the 27 bridges — as well as 42 others idenified "in an abundance of caution." Crews have begun removing and patching concrete, or adding more wood planks to 17 of the bridges.
The state considers three main elements when designating bridges: the deck, or surface; the superstructure, usually beams, girders and other elements that support the deck; and the substructure, such as abutments and piers that hold up the deck and superstructure. Each element is rated from zero (closed to traffic) to nine (nearly new), and if any element is rated four or below, federal standards require that it be rated structurally deficient.
Most of the structurally deficient bridges are rated in the midrange, from four to six, in the three categories, with deck deterioration the most common problem, according to the most recent list maintained by the highway agency. A structurally deficient designation doesn't mean a bridge is unsafe — which would prompt a closing — but that officials need to start planning for repairs, the highway administration says.
Some of these bridges are heavily traveled. In Howard County, for example, almost 188,000 daily cars drive northbound on Interstate 95 as it goes over Maryland 32, according to highway administration records.
Among the bridges that were ordered inspected are several along the Baltimore Beltway that are more than 50 years old, including those that span Benson Avenue and Leeds Avenue in the Arbutus area. They are part of a $56.7 million project that is expected to be completed in 2017.
Fixes for most structurally deficient bridges, though, are still in the design phase, and the structures remain on the list for a while.