The $82-million project replaced a severely deteriorated 1920s-era through-truss bridge with a 2,087-ft-long, six-span structure designed to serve this key border crossing for at least 100 years.

When the 1,200-foot-long Francis Scott Key Bridge opened in 1977, its enormous steel-truss design was the state of the art for river crossings. But in the decades since, a more modern design that has ...