IN THE MILLENNIAL year 2000, a harbinger of a future that might revive the past appeared in the form of a coyote that managed to reach Central Park. Subsequently, two more made it into town, as well as a wild turkey. The rewilding of New York City may not wait until people leave.
That first advance coyote scout arrived via the George Washington Bridge, which Jerry Del Tufo managed for the Port Authority of New York and New Jersey. Later, he took over the bridges that link Staten Island to the mainland and Long Island. A structural engineer in his forties, he considers bridges among the loveliest ideas humans ever conceived, gracefully spanning chasms to bring people together.
Del Tufo himself spans an ocean. His olive features bespeak Sicily; his voice is pure urban New Jersey. Bred to the pavement and steel that became his life’s work, he nonetheless marvels at the annual miracle of baby peregrine falcons hatching high atop the George Washington’s towers, and at the sheer botanical audacity of grass, weeds, and ailanthus trees that defiantly bloom, far from topsoil, from metal niches suspended high above the water. His bridges are under a constant guerrilla assault by nature. Its arsenal and troops may seem ludicrously puny against steel-plated armor, but to ignore endless, ubiquitous bird droppings that can snag and sprout airborne seeds, and simultaneously dissolve paint, would be fatal. Del Tufo is up against a primitive, but unrelenting foe whose ultimate strength is its ability to outlast its adversary, and he accepts as a fact that ultimately nature must win.
Not on his watch, though, if he can help it. First and foremost, he honors the legacy he and his crew inherited: their bridges were built by a generation of engineers who couldn’t possibly have conceived of a third of a million cars crossing them daily—yet 80 years later, they’re still in service. “Our job,” he tells his men, “is to hand over these treasures to the next generation in better shape than when we accepted them.”
On a February afternoon he heads through snow flurries to the Bayonne Bridge, chatting with his crew over his radio. The underside of the approach on the Staten Island side is a powerful steel matrix that converges in a huge concrete block anchored to the bedrock, an abutment that bears half the load of the Bayonne’s main span. To stare up directly into its labyrinthine load-bearing I-beams and bracing members, interlocked with half-inch-thick steel plates, flanges, and several million half-inch rivets and bolts, recalls the crushing awe that humbles pilgrims gaping at the soaring Vatican dome of St. Peter’s Cathedral: something this mighty is here forever. Yet Jerry Del Tufo knows exactly how these bridges, without humans to defend to them, would come down.
It wouldn’t happen immediately, because the most immediate threat will disappear with us. It’s not, says Del Tufo, the incessant pounding traffic.
“These bridges are so overbuilt, traffic’s like an ant on an elephant.” In the 1930s, with no computers to precisely calculate tolerances of construction materials, cautious engineers simply heaped on excess mass and redundancy. “We’re living off the overcapacity of our forefathers. The GW alone has enough galvanized steel wire in its three-inch main cables to wrap the Earth four times. Even if every other suspender rope deteriorated, the bridge wouldn’t fall down.”
Enemy number one is the salt that highway departments spread on the roadways each winter—ravenous stuff that keeps eating steel once it’s done with the ice. Oil, antifreeze, and snowmelt dripping from cars wash salt into catch basins and crevices where maintenance crews must find and flush it. With no more people, there won’t be salt. There will, however, be rust, and quite a bit of it, when no one is painting the bridges.
At first, oxidation forms a coating on steel plate, twice as thick or more as the metal itself, which slows the pace of chemical attack. For steel to completely rust through and fall apart might take centuries, but it won’t be necessary to wait that long for New York’s bridges to start dropping. The reason is a metallic version of the freeze- thaw drama. Rather than crack like concrete, steel expands when it warms and contracts when it cools. So that steel bridges can actually get longer in summer, they need expansion joints.
In winter, when they shrink, the space inside expansion joints opens wider, and stuff blows in. Wherever it does, there’s less room for the bridge to expand when things warm up. With no one painting bridges, joints fill not only with debris but also with rust, which swells to occupy far more space than the original metal.
“Come summer,” says Del Tufo, “the bridge is going to get bigger whether you like it or not. If the expansion joint is clogged, it expands toward the weakest link—like where two different materials connect.” He points to where four lanes of steel meet the concrete abutment. “There, for example. The concrete could crack where the beam is bolted to the pier. Or, after a few seasons, that bolt could shear off. Eventually, the beam could walk itself right off and fall.”
Every connection is vulnerable. Rust that forms between two steel plates bolted together exerts forces so extreme that either the plates bend or rivets pop, says Del Tufo. Arch bridges like the Bayonne—or the Hell Gate over the East River, made to hold railroads—are the most overbuilt of all. They might hold for the next 1,000 years, although earthquakes rippling through one of several faults under the coastal plain could shorten that period. (They would probably do better than the 14 steel-lined, concrete subway tubes beneath the East River—one of which, leading to Brooklyn, dates back to horses and buggies. Should any of their sections separate, the Atlantic Ocean would rush in.) The suspension and truss bridges that carry automobiles, however, will last only two or three centuries before their rivets and bolts fail and entire sections fall into the waiting waters.
Until then, more coyotes follow the footsteps of the intrepid ones that managed to reach Central Park. Deer, bear, and finally wolves, which have reentered New England from Canada, arrive in turn. By the time most of its bridges are gone, Manhattan’s newer buildings have also been ravaged, as wherever leaks reach their embedded steel reinforcing bars, they rust, expand, and burst the concrete that sheaths them. Older stone buildings such as Grand Central—especially with no more acid rain to pock their marble—will outlast every shiny modern box.
Ruins of high-rises echo the love song of frogs breeding in Manhattan’s reconstituted streams, now stocked with alewives and mussels dropped by seagulls. Herring and shad have returned to the Hudson, though they spent some generations adjusting to radioactivity trickling out of Indian Point Nuclear Power Plant, 35 miles north of Times Square, after its reinforced concrete succumbed. Missing, however, are nearly all fauna adapted to us. The seemingly invincible cockroach, a tropical import, long ago froze in unheated apartment buildings. Without garbage, rats starved or became lunch for the raptors nesting in burnt-out skyscrapers.
Rising water, tides, and salt corrosion have replaced the engineered shoreline, circling New York’s five boroughs with estuaries and small beaches. With no dredging, Central Park’s ponds and reservoir have been reincarnated as marshes. Without natural grazers—unless horses used by hansom cabs and by park policemen managed to go feral and breed—Central Park’s grass is gone. A maturing forest is in its place, radiating down former streets and invading empty foundations. Coyotes, wolves, red foxes, and bobcats have brought squirrels back into balance with oak trees tough enough to outlast the lead we deposited, and after 500 years, even in a warming climate the oaks, beeches, and moisture-loving species such as ash dominate.
Long before, the wild predators finished off the last descendants of pet dogs, but a wily population of feral house cats persists, feeding on starlings. With bridges finally down, tunnels flooded, and Manhattan truly an island again, moose and bears swim a widened Harlem river to feast on the berries that the Lenape once picked.
Amid the rubble of Manhattan financial institutions that literally collapsed for good, a few bank vaults stand; the money within, however worthless, is mildewed but safe. Not so the artwork stored in museum vaults, built more for climate control than strength. Without electricity, protection ceases; eventually museum roofs spring leaks, usually starting with their skylights, and their basements fill with standing water. Subjected to wild swings in humidity and temperature, everything in storage rooms is prey to mold, bacteria, and the voracious larvae of a notorious museum scourge, the black carpet beetle. As they spread to other floors, fungi discolor and dissolve paintings in the Metropolitan beyond recognition. Ceramics, however, are doing fine, since they’re chemically similar to fossils. Unless something falls on them first, they await reburial for the next archaeologist to dig them up. Corrosion has thickened the patina on bronze statues, but hasn’t affected their shapes. “That’s why we know about the Bronze Age,” notes Manhattan art conservator Barbara Appelbaum.
Even if the Statue of Liberty ends up at the bottom of the harbor, Appelbaum says, its form will remain intact indefinitely, albeit somewhat chemically altered and possibly encased in barnacles. That might be the safest place for it, because at some point thousands of years hence, any stone walls still standing—maybe chunks of St. Paul’s Chapel across from the World Trade Center, built in 1766 from Manhattan’s own hard schist—must finally fall. Three times in the past 100,000 years, glaciers have scraped New York clean. Unless humankind’s Faustian affair with carbon fuels ends up tipping the atmosphere past the point of no return, and runaway global warming transfigures Earth into Venus, at some unknown date glaciers will do so again. The mature beech-oak-ash-ailanthus forest will
