HARRISBURG — Four of Pennsylvania's 54 deck truss bridges that carry motorists on state highways have serious deterioration, according to new information released Tuesday in the wake of Minnesota's deadly bridge collapse.

After refusing for several months to release the bridge-safety ratings, the state Department of Transportation last week declared an about-face, despite what highway officials said were internal concerns about causing undue public alarm or revealing security weaknesses.

With the collapse of the I-35 bridge in Minnesota two weeks ago, bridge safety has become a high-profile issue across the country and prompted federal officials to ask states to re-inspect bridges of a similar design to the truss bridge that collapsed.

Bridge safety is also a familiar subject in Pennsylvania, which is home to more deteriorated bridges than any other state. Highway and bridge officials stress that all of the bridges that are open are safe for motorists to use, although some may be posted with weight or lane restrictions.

The four bridges that show "serious" deterioration are the eastbound and westbound spans across Six Mile Creek on Interstate 90 in Erie County, the Freeport Bridge and the Hokendauqua-North Catasauqua Bridge across the Lehigh River near Allentown.

The bridges are state-owned, except for the Lehigh River bridge, which is jointly owned by Lehigh and Northampton counties. All four are slated for replacement or rehabilitation in the next five to seven years.

The 45-year-old Freeport Bridge already had $5 million in emergency repairs last year to deal with deterioration that had forced a weight restriction. It has yet to receive a new inspection that could revise its safety rating upward, but is still scheduled for a massive rehabilitation in 2010 at a cost of approximately $50 million, PennDOT spokeswoman Valerie Petersen said.

The I-90 bridges, built in 1959 high above the creek, are the major artery between Cleveland and Buffalo. The spans were not designed for today's heavier trucks, and some of the secondary supports can shift and crack, said Bill Koller, the bridge engineer in PennDOT's northwest District 1.

The Hokendauqua-North Catasauqua, built in 1908, needs replacing because parts of the superstructure are rusting, said Glenn Solt, Lehigh County's capital projects manager. However, the need for approvals from the state and federal governments, which will pay 95 percent of the tab, means that construction may not begin for five years, Solt said.

"We're going to put a new one in as soon as possible,"' Solt said. "I wish it could happen so much sooner."

In all, Pennsylvania has 17 deck truss bridges that are classified as structurally deficient, including 13 bridges judged to be in "poor"' condition.

PennDOT grades bridges according to the condition of their primary structures. Those in "poor" or "serious" condition are of less concern to engineers than those graded as "critical" or "imminent failure" — the latter designation requiring the bridge to be closed.

Of the 25,000 state-owned bridges in Pennsylvania that are longer than 8 feet, about one-quarter are considered structurally deficient, the most in the country, according to PennDOT.

PennDOT bridges are inspected every other year, and more often if they are structurally deficient, officials say.

Pennsylvania's structurally deficient deck truss bridges (with county in parenthesis):<B>Serious deterioration</B>• I-90, westbound over Six Mile Creek (Erie)• I-90, eastbound over Six Mile Creek (Erie)• Freeport (Westmoreland, Armstrong, Allegheny)• Hokendauqua-North Catasauqua (Lehigh/Northampton)<B>Poor condition</B>• Rochester-Bridgewater (Beaver)• Koppel (Beaver)• Thomas J. McCall Memorial (Carbon)• I-476, over Muddy Run (Carbon)• I-476, over Pohopoco Creek (Carbon)• Donora-Monesson (Washington)• Dooker's Hollow (Allegheny)• Rankin (Allegheny)• Northwest Catasauqua (Lehigh)• Tacony-Palmyra (Philadelphia)(Three short spans are not included)Source: Pennsylvania Department of Transportation