Federal and state officials are slowly moving forward with plans to replace the bridge on U.S. 21 over Albergotti Creek, a span that has appeared on AAA Carolinas' list of the most substandard bridges in South Carolina for at least six years.

The latest sign of progress is that a half-acre parcel owned by Marines Corps Air Station Beaufort expected to be used for the bridge project has cleared a regulatory hurdle in the form of a mandatory review by the U.S. Department of Housing and Urban Development, according to a notice in the Federal Register.

Federal law requires HUD to examine unused or surplus federal property before the land can be sold or an easement granted, said Sue Brink, spokeswoman for Naval Facilities Engineering Command Southeast in Jacksonville, Fla.

The road project, expected to cost about $5 million and take about 18 months, is on schedule to begin next year, said Beaufort County engineering and infrastructure director Rob McFee.

The 62-year-old bridge will be replaced with a slightly wider and longer crossing, S.C. Department of Transportation officials have said. The bridge sits east of the air station along a stretch of U.S. 21 that connects northern Beaufort County to Interstate 95. It also serves as a hurricane evacuation route.

For several years, the Albergotti Creek crossing has ranked near the top of the AAA Carolinas' annual list of substandard bridges. It is deemed "structurally deficient" and "functionally obsolete" under federal guidelines. But DOT officials have maintained that the bridge is still safe.

About 28,400 vehicles cross it every day, and the DOT estimates that number will increase to about 42,000 vehicles daily by 2030.

Engineers have designed the replacement bridge in phases so that four lanes of traffic will remain open throughout its construction, a DOT spokesman has said.

Follow reporter Patrick Donohue at twitter.com/ProtectServeBft.