A 111-year-old Melan arch bridge in Paterson, N.J., over the Passaic River has received a now-invisible makeover with new cast-in-place concrete arch supports set within the stone masonry facade. Crews spent June wrapping up installation of pedestrian rail that reflects the long-lost original steel lattice.

Aileen Cho / ENR Chiara (left) and county engineers rehabbed bridge’s Melan arches.

The patented Melan arch, named after European engineer Josef Melan in 1893, combines steel reinforcing ribs with concrete to efficiently carry loads, says John Chiara, senior structural engineer with Lichtenstein Consulting Engineers, Paramus, N.J. The firm was acquired by Kansas City-based TranSystems last year. American engineer Edwin Thatcher adopted the arch for Paterson’s West Broadway Bridge, a three-span crossing some 300 ft long and 54 ft wide.

Growing traffic and frequent flash floods created the need to reinforce the bridge, which rises 9.5 ft from the abutment to the top of the arches. Carrying 20,000 daily vehicles, the bridge had a 10-ton weight limit, says Aura Mayer, engineer with owner Passaic County.

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Sparwick Contracting Inc., Lafayette, N.J., won the two-year, $5.2-million contract in 2006. Working on one bridge half at a time, crews installed a temporary bulkhead and tiebacks to support the structure while relocating utilities. Then, “We exposed the surface of the arch and repaired concrete spalls,” says Brian Fagersten, Sparwick vice president. After removing cinder fill that served as road base, crews installed a waterproof membrane around each 15-in.-deep arch. Crews installed 108 precast panels, 8 ft x 10 ft and 4 in. to 6 in. thick, to facilitate cast-in-place pours that integrate the new arches into the existing bridge.

The steel-reinforced arches, suspended between 1.5 in. to 3 in. over the old ones, now bear the loads. “The existing spandrel wall becomes a facade,” says Fagersten. To tie into existing approaches, the new profile is raised no more than about 1 ft.

Following historic preservation guidelines for the federally funded job, designers researched photos, postcards and an 1899 ENR article, says Chiara. “The bridge has been plagued by flooding throughout its history,” he notes. “Fortunately this has made it a subject for photography and it is well documented.”