This episode projects how long the nation's buildings and bridges will stand before the elements consume the steel and concrete, from the Empire State Building, Chrysler Building, Brooklyn Bridge and the Roosevelt Island Tramway in New York City to the Gateway Arch in St. Louis, and how once domesticated animals, like horses, will return to wild herds that roam America's grasslands. The episode also examines the ghost town of Rhyolite, Nevada, a town its designers wanted to rival Chicago, which was abandoned by people around 1910.
The great cities of mankind were built on metal, financed on gold and constructed from steel. In the absence of man, these metals seem well armored in the battle for survival, but what properties will allow some to crumble and others to survive?
One day after people, in the heart of Manhattan the Federal Reserve Bank of New York still guards the vast wealth of depositers who will never return to claim it. It holds more than half a million gold bars worth roughly $200 billion, the accumulated wealth of some 60 foreign governments and central banks. The gold is stored 80 feet below street level, the narrow opening to the vault is protected by a rotating 90 tonne steel cyclindar that forms an air and watertight seal with the surrounding 140 tonne steel and concrete frame. Gold is one of the most non-reactive metals on Earth, so when it's exposed to air or water its molecules resist disintegration, but other metals in New York City won't fare so well.
The steel canyoned walls of Time Square are still a glittering urban shrine, but the streets have turned eerily quiet. In the time of humans, it was one of the loudest places in a very loud city. Sustained exposure to sound over 75 decibels was deemed dangerous to human ears yet the ambient noise here measured 80 decibels, honking horns peaked at 90 decibels and a passing ambulance siren screamed at 120. Now, these sounds are no more leaving just the 50 decibel hum of air conditioning units.
2 days after people, and the New York city power grid is failing and so is the trademarked glow of hundreds of illuminated signs. These streets have seen blackouts before, in 2003 a massive East Coast powercut plunged Time Square into darkness for more than 12 hours, but this time the blackout is permanant.
During the day, New York's urban jungle is prowled be creatures unaccustomed to fending for themselves, the horses that once carried police officers and pulled Central Park carriages must adapt to a life with no humans to care for them. In a world of concrete and steel, can these horses survive?
875 miles west of New York City, the breaking point of metal is about to be tested. With a dozen breweries St. Louis was known as America's brewing capital. In the city that once quenched the thirst of a nation and the world 3 million kegs worth of beer continue to ferment in several thousand massive steel vats. Inside these fermentation tanks, yeast is used to turn sugars into alcohol, carbon dioxide is given off as a bi-product which creates increasing pressure in the tank. Automatic safety release valves normally prevent pressure from getting to high in a tank, but fermentation also creates something called krausen a meringue-like residue that rises to the top of the tank, the extra heat triples the amount of krausen rising to the top where it clogs the pressure release valve. In 2009 a fermenting vat explosion tore a 30 foot hole in the roof of a New Orleans brewery. In St. Louis only 36 hours after people these violent eruptions blast holes in roofs as they unleash their intoxicating contents.
Back in New York City, the problem isn't beer, but water. Without power the 700 pumps that once emptied this subway system of an average of 13 million gallons of water a day are no longer operating, the tunnels are already beginning to flood.
It's 6 months after people, New York City is dark, except for a strange glow in Time Square. Installed in 2009, this illuminated beacon of the human past is a billboard that doesn't rely at all on the municipal power grid. 90% of the sign's power is generated by 16 wind turbines, the rest comes from an array of 64 solar panels, the sign's power plant generates enough electricity to power 6 houses for a year, the turbine's blades were designed to resist freezing in Winter and to automatically slow in hurricane force winds to prevent damage, the sign should keep glowing for years, unless something unexpected happens.
1 year after people, the plaza of the Rockefeller Center in mid-town Manhattan is still a gathering place, only now it's animals that congregate here. In the time of humans, this concrete chasm was a plaza that was transformed into an artificial ice rink every Christmas, this Winter nature provides its own ice. In the Spring, the sunken plaza turns into a giant flower pot. Lording over this urban garden is the Statue of Prometheus, a figure from Greek mythology credited with creating mankind, he know presides over the destruction of what man has created.
1 year after people, the slow decay progresses in silence, but soon the sounds of crashing steel and stone from above will turn Manhattan into an island of destruction and something in their bones will bring down the dinosaurs.
3 years into a life after people, every street corner in New York City is dark, except for one, but the wind and solar powered billboard in Time Square finally flickers out, it's not for lack of power, just a simple matter of having nobody to change the lightbulbs.
Meanwhile the survivors of the urban horses that once patrolled Time Square and pulled tourists around Central Park have fled the city, but can they possibly survive long in a life after people? But soon the gardens and golf courses will turn into forests that don't provide the grassy, grazing environments that horses need. In order to survive, these horses need to find a suitable habitat in a hurry. Surprisingly, their best bet is to head for the beach, the grassy Barrier Islands of the Atlantic coast have already proved their ability to sustain herds of wild horses. In the time of humans, several hundred of them made their home on Assateague Island, just off the coast of Virginia and Maryland, the descendants of horse brought here by man 300 years earlier.
10 years after people, one of the most unusual steel structures, the Gateway Arch, still stands along the Mississippi River in St. Louis, little's changed since the last day humans packed its observation deck high above the Mississippi River. At 63 stories it is the tallest structure in the city and it might prove to be its longest lasting. Although it's said that the architect Eero Saarinen designed it to stand for a hundred years, its slender form looks vulnerable in a life after people. Unlike a skyscraper, the Arch doesn't have a steel skeleton, its strength is designed from double walls of stainless steel plates filled with concrete. The surface of the stainless steel is covered with the film of chromium oxide that can resist corrosion for decades. The Arch remains as the gateway to the West, at least for now.
At the Rockefeller Center, the walls of the buildings have undergone a strange transformation. Plants have already shown a relentless drive to colonize places in New York where they were never supposed to be. This is the Highline, an elevated railroad track that runs for 22 blocks along Manhattan's West side, it was completed in 1934, allowing trains to make pick-ups and deliveries directly from the warehouses and factories in the meat packing district to Hell's Kitchen, but rail traffic declined in the 1950s as more cargo was transported by road, the last trains rumbled along parts of this line in 1980. This ribbon of wilderness high above the city streets is proof that the Big Apple will turn green very quickly in the absence of humans.
35 years after people, the mansion lined beaches along Westhampton, a Long Island getaway for New York's rich and famous no longer provide an escape from the troubles of the city. The opulent homes were always perched precariously on the edge of the sea, many houses were even built on the barrier islands that separated the mainland from the pounding Atlantic surf. In the 1990s a series of Atlantic storms breached the barrier island at Westhampton destroying many homes. After that, the US Army Corps of engineers rebuilt the barrier island and ensured it was constantly fortified by dredging sand from the sea bottom to build up and reinforce the beach. Every 4 years the army corps pumped up to 1 million cubic yards of sand onto the beach, but without the herculean effort of humans, the mansions of the rich and famous fall victim to the waves.
50 years after people, dinosaur skeletons remain standing as relics of a time long before humans walked the Earth. Their metal supports have kept them upright for decades, but there's a disease growing in their bones, it's called Pyrite Disease named after the mineral pyrite also known as Fool's Gold. It forms during the fossilization process as bacteria trigger a chemical reaction that replaces soft tissue with hard crystals. If fossils are kept under the right conditions, the pyrite inside remains stable, but in the presence of humid air the mineral reacts with oxygen and expands. These growing crystals crack the bones from within. In 1999 the Triceratops skeleton on display in the Smithsonian Institution for almost 100 years had to be dismantled and conserved, its bones ravaged by this disease. Only half a century after people in the world's great natural history museums the reign of the dinosaurs is coming to an end.
High above New York City, the stainless steel crown of the Chrysler Building still shimmers. In the time of humans, the building's low maintenance steel only had to be cleaned twice in a span of 76 years. On the 61st floor the eight stainless steel eagle gargoyles that keep watch over the city are constantly buffeted by high-level winds. Its connection to the building corroded one of the wingless eagles takes its first and final flight.
Around the world the sounds of crashing steel and stone become more frequent as the years go by, it's a reality that is already tearing apart this once thriving spot in the Nevada Desert, who's founders intended it to rival the city of Chicago, it's soon to be a reality in America's great cities where the modern structures have a surprising flaw that can destroy them before their time.
90 years after people is enough to ravage even cities that were built to last, it's a future that has already come to pass here. While modern cities were built on steel this one lived, and died by gold. This is Rhyolite, Nevada, a former gold-mining town 120 miles from Las Vegas in the unforgiving landscape near Death Valley. When gold fever struck the Nevada mountains in 1904, Ryolite's population of 2 miners jumped to 1200 people in just 6 months, some found great success. In its first 3 years the largest mine in the area produced over $1 million in gold, the equivalent of more than $24 million today. These riches fueled the construction of a town that the city's founders hope would rival Chicago. By 1908 there was as many as 8000 residents. Despite the early promise of the mines, much of the most valuable ore in the area proved too difficult to extract and a nationwide financial crisis dried up the capital needed to sustain the hunt for gold, by 1910 the boom was over, the town was left to die. Rhyolite may look like a classic old West ghost town, but the structures here tell a unique story. This is the Cook Bank Building, once the crown jewel of Rhyolite it guarded over $200,000 of hard-earned wealth, the equivalent of roughly $4 million today. In its prime the bank boasted marble stairs and stained glass windows. Had it been built of wood, like most structures of the era, the walls would have collapsed long ago, but this was one of the earliest multi-story buildings in the West to be constructed from reinforced concrete, a technique that had only been in use for 15 years in the United States. Built to last the concrete has stood tall against the ravages of time, but time is running out. The enemy in Death Valley is not moisture, this is one of the driest places on Earth, located in the mountains Rhyolite still averages only about 6 inches of rain a year. What there is plenty of is wind, and sand. The abrasive grinding action of the desert wind is like a sand-blasting tool, the particles erode surfaces and penetrate into cracks, the concrete delaminates causing layers to separate from within and the structure crumbles. Man helped nature along in its destruction of Ryolite, people began scavenging wood supports and other useful materials that were scarce in the remote desert. At the town's general store. where miners once came to buy the tools of their trade, the disappearance of its internal wooden structure has hastened the destruction. Even glass, a substance made from sand, is a primary building block in one surviving home, the Bottle House was made from 30,000 empty whiskey bottles, although the house has been restored several times including in 1925 for use in a silent film, the glass itself is biologically inactive and does not corrode. Rhyolite's ambitious founders hoped to build a metropolis in the desert, instead after 90 years it is on the verge of vanishing off the map.
100 years after people, the sound of snapping steel reverberates down the corroded canyons of New York City. The cables of the suspension bridges connecting Manhattan to Brooklyn and Queens are disintegrating. The roadway of the Brooklyn Bridge is held up by just over a thousand vertical suspender or hanger cables, each about the thickness of a human wrist. Each cable is made up of 7 strands of steel twisted around each other to total 100 miles of steel in every cable, the cables are galvanized, covered in a protective coating of zinc which corrodes much more slowly then the underlying steel. A few cables snap, the remaining cables snap and the roadway collapses into the waters of the East River below.
Up river from the Brooklyn Bridge, the city's most adventurous commuters once relied upon another steel cable structure to get them into Manhattan. The only thing holding up the Roosevelt Tramway is a pair of 2 inch diameter wire ropes. The weak point is the spot where the cable cross over the steel support towers. In the time of humans, the cables were shifted roughly 100 feet every 5 years to keep any one point being in contact with the towers for too long. Even though the tram hasn't moved along the cable for 100 years wind has continued to buffet the tramway causing stress on the wires near the towers, they snap and the tram car plunges 250 feet into the East River.
150 years after people, at the Rockefeller Center where once a tree had to be brought in by road to celebrate the holiday season, the greenery is now on permanent display. The skyscrapers that made New York famous have transformed into vertical ecosystems. 150 years after people sees the beginning of the era of the great building collapses in New York City. Surprisingly, it's the newer buildings that are crumbling the fastest. While the walls of older buildings had to be strong integral parts of the structure, new types of steel developed in the mid 20th century allow most of a building's weight to be carried by the inner columns, so most of New York City's post-war skyscrapers were built using a glass and steel curtain wall technique, in which the outer walls just form a lightweight protective skin of steel and glass.
200 years after people, with the collapse of the modern skyscrapers, New York's silhouette is a throwback to the Great Depression. Completed in the early 1930s the Empire State Building and the Chrysler Building once vied to be the tallest buildings in the world. The Chrysler held that crown for less than a year before the Empire State surpassed it. Now, the rivalry is over, the Empire State Building slips from the skyline. The Chrysler Building, the first of man's skyscrapers to stand taller than 100 feet is once again the tallest building in the city, but it's reign won't last for long. The deteriorating columns can no longer support the floors. The skyline of New York is now unrecognizable. In fact few very tall structures remain standing in the cities of the world. One of the exceptions is the Gateway Arch in St. Louis, but a small part added to the structure at the last minute holds the key to its destruction.
For 250 years after people, St. Louis' Gateway Arch has worn its stainless steel skin as armor against the dragon's breath of corrosion, but stainless steel isn't invincible. The thinnest point are the 2 sections called the keystone, steel triangles 17 feet long by 18 feet high, the last pieces to be installed. The keystone is so critical to the structure's stability that until it was inserted, a temporary stabilizing truss had to be used to keep the 2 legs from collapsing. Before the pieces were lifted into place on the 28th October 1965, a Roman Catholic preist and a rabbi blessed the keystone, but now the prayers of man are of little help. The keystone buckles and plummets from the structure. The first 250 years after people have seen the skylines of our cities crumble, now the ruins will be swallowed up by water, soil and plants.
1000 years after people, New York's skyscraper canyons are now just canyons, rivers flow where taxis once patrolled.
10,000 years after people, on the new shoreline of the expanding sea wanders a pack of wild horses, the descendants of the urban equines that thousands of years ago that protected and entertained the humans of New York City. The high salt content in their seaside food supply means that they have to drink twice as much water as their domesticated ancestors once did, and the grasses here are so deficient in nutrients that the horses have evolved a shorter stature in response to the poor quality of their diet, still they have survived. Buried in the ground beneath their feet, a corroding steel crypt holds tight to its precious contents. Once 80 feet below street level, the Federal Gold Vault is now hundreds of feet below ground and inundated with water from rising sea levels. Inside the largest stockpile of gold ever assembled on Earth remains well preserved. Although the steel will eventually corrode the gold bars themselves should last not just for thousands of years, but even millions.
The 24 carat gold will live on as a precious metal, once mined, molded and guarded by humans it was now returned to the Earth in a life after people.