When drivers began using two new lanes of the Bayonne Bridge between Staten Island and New Jersey last month, they crossed not only the Kill Van Kull waterway but also a nexus between a historic engineering past and a modern engineering present. The new deck still traverses the 85-year-old, Othmar Ammann-designed steel arch, which, when the bridge opened, was the longest of its kind in the world. Today, within that historic arch, a new elevated deck rises 64 ft higher than the old one, a construction feat officials believe is another first of its kind.

“There is no precedent,” says Thomas McLaughlin, area manager with HDR Inc., which led the design with WSP | Parsons Brinckerhoff. “We looked at other projects and couldn’t find anything like it.”