"Today on "Impossible Engineering"..." "The London crossrail," "Europe's biggest construction project." "The new crossrail trains will carry 200 million passengers in and out of London every year." "It's very exciting." "Pushing urban construction to its limits..." "These machines allow you to pump 60 tons an hour." "It's quite an art to see." "...Engineers must look to the innovative pioneers of the past..." "It's amazing that they were able to build this bridge in this torrent." "Aah!" "I love the industrial revolution." "...To make the impossible possible. captions paid for by discovery communications" "London -- one of the world's most populated megacities." "As the home of almost nine million residents, with 31 million visitors each year, this nearly 620-square-mile Metropolis is grinding to a halt." "It's a problem that engineer and commuter Camilla barrow experiences every day." "London is a fantastic place to live." "Everyone wants to be here." "There's a lot going on." "However, catering for these people in terms of transportation is critical, and as you can see right now, it's bursting at the seams." "Every day, more than 11 million people utilize London's vast transportation system, including 3 1/2 million riding the London underground alone." "The current London underground is about 150 years old, and it's a fantastic system and caters for a large capacity." "However, it was never anticipated that it would cater for this amount of people." "To solve this seemingly insurmountable problem, engineers are embarking upon Europe's biggest construction project." "10,000 workers spread across 40 different construction sites are creating a brand-new rail network straight through the capital's heart." "For operations executive Michael Bryant, this project poses a series of complex challenge." "Underneath London is a veritable labyrinth of tunnels for all sorts of purposes." "It's extremely complex." "Lots of the buildings there, particularly the large buildings, like the shard, have piles that go down 20," "30, or even 40 meters down into the chalk level, so it really is like threading a needle." "Stretching 73 miles, the network will pass through 40 stations." "The system features an astonishing 26 miles of freshly dug tunnels, intricately woven through the existing underground rail system, and deep building foundations of this complex subterrane world." "In 2012, eight gigantic 1,100-ton tunnel-boring machines operating 24 hours a day, 7 days a week begin creating this new network." "Right now, crossrail is a megaproject." "It's very complex." "It's costing approximately £15 billion." "It's probably the type of challenge that a civil engineer would dream of through most of his or her career." "Not only do engineers have to find room for 26 miles of new tunnels." "They must also create space for 10 new stations, including one serving the financial district, canary wharf." "All of the land is full, as you can see up there, so the only place to do it was in the water." "The challenge was to deliver a concrete box 28 meters below water level." "The option of failure just did not exist." "So how do you create a train station deep inside the river Thames?" "To accomplish the impossible, engineers must look to the greatest innovators of the past." "Traveling along Rome's river Tiber, professor Rhys Morgan is in search of an ancient structure that has withstood the power of mother nature for millennia." "Oh, wow!" "It's amazing that they were able to build this bridge thousands of years ago in this torrent." "Oh!" "Aah!" "Aah!" "Oh!" "Constructed in 62 B.C., the Pons Fabricius is the oldest Roman bridge still standing." "That's a real strong current there." "The foundations must be extraordinary to deal with that river." "This bridge has endured it all -- wars, earthquakes, floods, and countless numbers of people, horses, and carriages." "But the foundations of the bridge still endure." "The Roman curator of roads" "Lucius Fabricius commissioned the bridge." "The very core of the bridge, the foundation in the center, is where the clever bit happened almost 2,000 years ago." "The Roman engineers had to come up with a revolutionary method of building while the water was in full flow." "What they designed was ingenious." "It's known as a cofferdam." "The cofferdam first required a ring of timber piles that were bound together and driven into the riverbed." "A second, larger-diameter pile posts was then added to encircle the first." "The gaps between the piles would be filled with Clay to waterproof the central enclosure." "So they had to pack the Clay all around really densely." "And then, when they were happy, they would remove the water from inside the inner ring." "Look at that." "It's really working." "And now I'm down to the riverbed." "When all the water was removed from the inner ring, the builders could start working on the foundations." "I'm going to use this stick as the central pier." "And there you go." "Fantastic." "Once the foundations were built and the pier could be put in place, the cofferdam could be removed, and the rest of the bridge could be built around it." "And there we are, Roman engineering at its best." "The revolutionary use of a cofferdam at the Pons Fabricius means this over-200-foot bridge still stands as a testament to Roman innovation." "When it came to building solid structures in the water, Roman engineers really did make the impossible possible." "The engineering team at canary wharf are taking the groundbreaking cofferdam and implementing it on a gigantic scale." "They drive nearly 1,400-foot-long tubular steel pipes into the dock floor to create a cofferdam big enough to hold the new 820-foot-long station." "But this behemoth construction project could pose major problems for the high-rent neighbors." "The traditional method of creating a cofferdam is actually to hammer steel members into the ground." "And as you can imagine, that makes a lot of noise, a lot of vibration, creates a lot of dust -- major disruption." "So we had to come up with something that was better." "To overcome this hurdle, engineers utilize a new technique called silent piling." "Rather than hammering the piles, a state-of-the-art machine, called a giken, does the work." "Weighted to the dock bed and using powerful hydraulics, it silently twists and pushes the first three piles into the ground." "The machine then crawls across and secures itself to those piles, using them as anchors, before pushing in the next one." "This process is repeated until the cofferdam wall is complete." "We went for the first three years of the project without a single complaint from any of the neighbors." "Once the cofferdam walls are in place, engineers can begin the mammoth task of removing the water." "We progressively took out 98 million cubic meters of water from the cofferdam, and that's equivalent to 40 Olympic swimming pools." "336,000 tons of material are then excavated until finally engineers reach a solid foundation" "60 feet below, from which to begin construction." "So we have four floors below water, a floor at water level that we call promenade, and then there's two floors above and the roof garden." "At maximum capacity, 24 trains an hour will carry a staggering 68,000 passengers a day across the network faster than ever before." "But creating this station is only a fraction of this megaproject, and to complete the roving underground system, engineers must look to innovations of the past..." "French explorers have left here to travel the globe." "...To make this impossible rail system possible." "Deep below the streets of London, the biggest construction project in Europe is underway." "A complicated new rail system with 26 miles of tunnels and 10 new stations is unfurling." "It's a fantastic project." "You're working with some of the top, top expertise in the industry." "It's very exciting." "But creating a colossal new railway above and below one of the planet's most densely packed cities raises significant engineering challenges." "The most obvious issue is working around this massive infrastructure that's already in place." "We've got people living here, people working here." "To carve out a 130-foot-deep labyrinth of tunnels beneath the city, eight 10-million-pound mega boring machines are required." "These monsters are 23 feet in diameter and as long as 14 double-Decker buses." "Project manager Jules Boyd must make sure London's infrastructure and residents remain intact." "One of the constraints on the crossrail operation, which is a massive operation, is to virtually pass by unnoticed to our neighbors." "When the tunnels are dug, problems can occur as the surrounding earth resettles, causing cavities, or settlement troughs, to appear." "If the settlement trough increases, a building's foundations could shift, causing structural damage." "This is a real historical center of London, and it has to be protected." "So how can engineers keep these ancient buildings safe?" "It's a challenge that would require some inspiration from the great innovators of the past." "Tunneling under cities isn't new." "In the 6th century B.C., to have a supply of fresh water that couldn't be cut off by enemies, the residents of the Greek city Samos dug underground aqueducts." "They must be getting thirsty by now." "Cheers!" "Whoo!" "The soft volcanic rock beneath Naples meant huge networks could be dug for businesses, churches, and even a theater, where emperor Nero is said to have performed." "Ooh, he's on fire tonight." "Limestone mining under Paris created tunnels for what would become the world-famous catacombs, where the bones of six million former inhabitants now reside." " Uh-oh." "Hold on." "Push." "But any city excavation comes with a risk." "Ah, that is better." "To unearth one of the greatest engineering breakthroughs," "Dr. Rhys Morgan is exploring the northern coast of France." "Here at the historic Dieppe harbor once stood a massive lock called a sluice gate." "This large sluice gate would have opened, allowing the ships to come in and out of the harbor." "The gate had been constructed to stop the buildup of silt and pebble deposits and was a vital tool in keeping the harbor entrance clear." "It was around about the end of the 18th century that the sluice gate stopped working, and this had a real impact on the economy." "The gate's foundations no longer held their weight," "and in 1802, French civil engineer" "Charles Berigny had an inspired idea." "So this is my demonstration of the sluice gate and the problem that was happening underneath." "First of all, we had the rocks on the bottom of the seabed." "On top of the rock was a softer top layer, and it was on top of this softer top layer that the foundations of the sluice gate sat." "Now, the problem was that the water coming in through the harbor was going underneath the foundations of the sluice gate, and it started washing away and eroding the softer particles of the top layer, and that meant that the foundations" "of the sluice gate would be destabilized." "Berigny's solution to the problem was brilliant." "First of all, Berigny drilled a series of holes five foot deep through the foundations of the sluice gate, down into the soil where it eroded away." "And then this was the really ingenious bit." "He got a piston pump, what he called a blow pump, and he filled that with Clay grout." "And with a series of hammer blows, he forced the cement down into the soil below." "The cement's pouring through the holes, filling up this subsoil below and making those foundations nice and stable." "As Berigny's Clay grout was hammered through the predrilled holes, it spread out beneath the masonry foundations, squeezing into and filling the gaps created by the erosion." "After a period of time, the grout set hard." "Okay." "We've left it awhile." "We're gonna see how it set." "Because it's solidified, it just stays in place, and that would have really helped the foundations of the sluice gate." "Berigny's work was a resounding success." "This was the very first example, from Charles Berigny, of injection grouting, and it's used in civil engineering projects all over the world today." "Fantastic." "But adapting this engineering breakthrough to support an entire city is on an altogether different plane of difficulty." "To keep London from falling down, the crossrail team must once again make the impossible possible." "In London, engineers are working on the largest construction project in Europe -- the crossrail." "But keeping the city standing above this sprawling network of hollow tunnels relies on an early-19th-century breakthrough -- injection grouting." "Taking Charles Berigny's revolutionary engineering one giant leap further, the crossrail team are advancing these injection techniques to create one of the most sophisticated stabilizing systems on the planet." "Up on the corner of this building, there is one of the many a.T.S.Es." "There's another one up here, and you'll see targets." "These are essentially prisms." "High-tech surveying instruments known as automatic theodolite systems, or a.T.S.Es, are placed strategically across the city." "The a.T.S. Fires a beam of light at its reciprocal prism." "Engineers use specialized computer software to continuously measure the angle of the beam." "If the angle changes too much, this can indicate a shift in the foundations." "If any of these points starts moving, then the grouting program can be tuned to actually compensate for any settlement." "Underground, the team is reacting to new information from the aboveground a.T.S.Es." "At 10-foot intervals along the length of the grouting tunnel are a series of injection pipes that fan out above the tunneling work and below the delicate buildings." "Principal engineer cliff kettle is getting the grout to its final destination." "So grout comes via the injection line from the piloted pump, will come up this bore hole, will isolate the individual sleeve." "This rubber sleeve will push open." "The grout will exit here, at a fracture in the ground, and it will go into the ground." "As the injection rods are pushed into position, over six gallons of grout at a time are forced out through the rods and into the fissures of the ground, ultimately leveling the foundations and lifting the buildings back into place." "Some of the facades of these buildings here are 70,000 tons." "We see on a daily basis that just the injection of maybe three or four cubic meters of grout can move that building several millimeters." "Spanning five years, it's the biggest compensation project the world has ever seen." "Compensation grouting is absolutely vital for the project because it does something that there is no other process for." "There are many locations across crossrail where the excavation couldn't have been completed without the protection provided by compensation grouting." "Excavating tunnels safely is one thing, but converting them into a high-tech rail network is a greater challenge." "To accomplish this monumental task, project manager Jules Boyd is excavating these sprawling tunnels with massive tunnel-boring machines." "The TBM's obviously a big machine." "It's the factory that builds segments of one size." "It's building very fast." "As TBMs dig, they automatically line the freshly exposed Clay with prefabricated concrete slabs, quickly shoring up and sealing the walls." "But when they arrive at a future station site, these engineering behemoths hit their limits." "It's not very flexible in terms of size." "It will build one size tunnel only, which is what it's made it do." "And to sculpt more complex, cathedral-like stations, engineers must address a serious problem." "If the freshly exposed Clay is left unlined for too long, the unstable walls could collapse." "To prevent disaster, engineers must work fast and draw from the pioneers of the past." "The techniques that are used here eventually led to an innovation that would really have a huge impact on the engineering world." "Make the impossible possible." "Engineers in London are doing the seemingly impossible, creating a new rail system both over and under the city's congested core, but to accomplish this impossible task, the crossrail team must draw on the work of an unlikely innovator." "At the famed natural history field museum in Chicago, science administrator Mark Alvey is discovering how one man's passion for preservation helped create a revolutionary engineering tool." "These are the field museum's famous fighting bull elephants." "They were mounted over 100 years ago, and they're still one of our most iconic exhibits." "Created by explorer and the so-called father of modern taxidermy Carl Akeley, they mark a milestone in natural history display." "Carl Akeley was the museum's chief taxidermist from 1896 to 1909, and he experimented with various sculpting techniques involving Clay and plaster." "His techniques were really revolutionary." "Not only did Akeley want to display the animals in lifelike detail, but their surrounding environment, too." "And the techniques that he used in creating artificial rocks, like the ones you see here, eventually led to an innovation that would really have a huge impact on the engineering world." "During his search for lifelike perfection," "Akeley developed a new way of covering fake rocks with plaster of Paris." "And you can see that if we were to try to paint it by hand, it'd be very tiring and end up with very uneven results." "Now, if I use my gun here, you can see you get a much more even consistency." "It goes on faster." "You can cover your surface much more quickly." "Previously housed in a different building, the museum's director asked if Akeley could make something on a bigger scale to fix the museum's crumbling walls, so Akeley came up with a game-changing solution." "He devised a way of shooting dry plaster through one hose that would meet a jet of water under great pressure in another, mixing at the nozzle." "With this, Akeley created the world's first cement gun, and he went on to plaster the exterior of the museum." "The cement gun was soon modified, improved, and adapted for all kinds of industry and to create animal enclosures in zoos." "What Akeley achieved would be a template for all modern cement guns across the world, emphatically transforming the construction industry." "It's been used for anything from bespoke architecture..." "To pool lining..." "And even cliff stabilization." "Carl Akeley was a real pioneer." "His contributions to the world of engineering are truly remarkable." "At crossrail, a premixed wet concrete known as shotcrete is pumped through a specially adapted, supersized, and automated version of Akeley's machine." "At the nozzle end, high-pressure air is used to accelerate the mix towards its target." "Historically, people used to spray by hand." "These machines allow you to pump up to maybe 60 tons an hour." "This sophisticated fast-curing mix of shotcrete stabilizes the walls and forms the permanent tunnel lining." "This is the shotcrete." "It's essentially a concrete mix with small aggregate." "It's got these things, which are like small high-tensile steel fibers." "They're like reinforcing bar, effectively, on a micro scale." "I've worked on quite a lot of tunnels." "This is exciting." "There's a lot going on, and we're changing the culture to one that is infinitely more safe than it has been historically." "With a staggering 26 miles of brand-new tunnels now constructed, the momentous task of creating a high-tech railway is in progress." "We're now in our tunnel fit-out phase." "We're putting in our ventilation, all our high-voltage power and signaling." "And it's starting to look like how it'll look when trains will run through it." "And the biggest and most challenging job is laying the tracks." "On our project, we have four different types of track." "There's approximately 108 meters is each section, and you've got about 47 kilometers of this across the project." "But just how do you install this many miles of rail through an elaborate tunnel system?" "To do this, engineers must look to the past..." "What incredible feats of engineering." "I love the industrial revolution." "...To make the impossible possible." "The London crossrail is Europe's largest construction project, extending the city's existing underground transit system by an impressive 26 miles." "But to install so many miles of new track, modern engineers must look to breakthroughs from the past." "What incredible feats of engineering." "I love the industrial revolution." "Architectural historian Jen Masengarb is in California discovering the secrets behind one of America's most audacious construction projects." "In the early 1800s, it would have taken more than six months to cross the continent by horse." "But all that changed on July 1, 1862." "The signing of the pacific railway act by Abraham Lincoln authorized two companies to build an 1,800-mile-long railway between California and Nebraska." "And the two railroad companies had an incentive to move fast because they were paid by the mile " "$32,000 per mile." "And so they were off, union pacific starting in the east and moving west, central pacific starting in the west and moving east, racing across the continent to each other." "Despite the challenging terrain, union pacific workers were soon laying an astonishing 4.2 miles of track a day." "Key to their staggering progress was a method devised by two brothers," "Jack and Dan casement." "The casements' method involved creating an entire moving city." "Locomotives pulled sleeping berths, dining cars, and kitchens, providing everything for thousands of workers." "This might look like just a simple cart, but it's got a couple really cool features." "Each cart had these two iron bars along the front and the back, which made it possible for the iron rails to slide to the edge." "And then these rollers positioned the rail right into place, so it could be slid right down on the ties." "It saved valuable seconds, and all those seconds added up along the project really made a difference." "For the ingenious cart to be effective, the workers split into two teams." "The first team used a horse and wagon to deliver the railway ties to the front of the line, laying them in place with a pair of tongs." "At the same time, another crew would be in the back, lifting the rails into position on this cart." "Two men at the front of each rail, two men at the back." "And then this cart would be pushed to the front of the line." "Wheel out." "As the cart moved into position, it was the responsibility of two workers at the front to grab the rail with their tongs and pull it off the cart and then two workers in the back to align the two rails." "The foreman would yell "good iron,"" "and the cart would move forward." "Good iron." "More here." "Behind the cart, other men, called strappers, spliced the rails together at the joints." "Behind the strappers, spikers secured the rails to the wooden ties with spikes." "And then more carts came from behind with more materials to lay." "Hearing of union pacific's success, central pacific also adopted this swift technique." "The casement method revolutionized track laying, and by may 10, 1869, just five years after work had started, the two construction crews met, and a golden spike was planted to mark this American engineering triumph " "the transcontinental railway." "At crossrail, the engineers are taking the casement method and giving it a 21st-century upgrade." "Behind me is the multipurpose gantry, and really, mpg is a real-life transformer." "We have four of them on this project that were designed for crossrail." "These modern-day, million-dollar casement trolley cars drag 350-long sections of steel rail into position and place them on both sides of the tunnel floor." "You've got approximately 47 kilometers along routed rail, so a large amount of track we need to install, all through utilization of the mpg." "Next, the ties, or sleepers, are positioned in between the rail sections." "This mpg can lift up 28 sleepers in one go and position them in exactly the correct location." "Across this project, we have about 70,000 sleepers we're trying to lay." "Finally, this versatile machine lifts the rail onto the ties, and concrete is poured to secure the railway into position." "The mpg is a real solution to address the complexities and the magnitude of the task we have working in this environment." "But building an intricate and massive rail network like crossrail is one thing." "Ensuring the safety of the 200 million yearly passengers is a different story." "To accomplish this, engineers must look to a novel innovation from the past..." "This is the world-famous Coney Island, a place that's provided entertainment and thrills for over 100 years." "...To produce more impossible engineering." "Crossrail -- Europe's largest infrastructure project." "This massive construction is gearing up to completely change the face of travel for millions across London." "This $18 billion network is in the final stages of construction." "The new crossrail trains will carry 200 million passengers in and out of London every year." "But how will engineers transport an extra 200 million passengers safely from street level to stations as much as 130 feet below ground?" "To address this challenge, they look to the uplifting work of an innovator of the past." "Mechanical engineer Michael Tobias is exploring a thrill-seeker's paradise in Brooklyn, New York, in search of the unlikely origins of an everyday piece of engineering." "This is the world-famous Coney Island, a place that's provided entertainment and thrills to new yorkers for over 100 years." "Up until the 1930s, this iconic attraction was the largest in the U.S." "Incredible." "But in 1891, here at Coney Island," "American inventor Jesse Wilford Reno pioneered an altogether different type of ride." "Reno's invention was a prototype of the world's first working escalator." "And it caused a sensation." "Named the inclined elevator," "Reno's ascending movable walkway reportedly carried 75,000 people in just the first few weeks." "Reno's design was a sloped walkway, very similar to how a conveyer belt works." "There's two gears, at the top and the bottom, a motor on the top pulling the walkway up, down, and over again." "With its steep incline of 25 degrees and a 7-foot rise," "Reno attached strips of wood, or cleats, to the treads to provide traction." "And most ingenious of all, at the end of the ascent, the cleats disappeared through a reciprocal set of cone-like prongs that safely lifted the passengers' feet off the disappearing treads, enabling the track's continuous motion." "Reno's invention was soon installed in New York's transport system." "And elsewhere in New York, other engineers were also working on their own escalator designs." "It was here at Macy's flagship store where Elisha Otis, inventor of the elevator, installed one of his earliest escalators." "But Otis' plans incorporated steps." "And by combining them with Reno's cleat and comb design, the escalator made for a smooth ride and safe exit." "Installed in 1927, these are thought to be the world's last-remaining wooden step escalators anywhere in the world." "Each step in the escalator has two sets of wheels, which roll along two separate tracks." "The upper set are pulled by the rotating chains while the other sets simply follow behind." "The tracks are spaced apart so that each step will always remain level." "At the top and bottom of the escalator, the tracks level off to a horizontal position, flattening the stairway." "These escalators stand as a testament to the engineering brilliance of the men involved and form the blueprint for all modern escalators." "Back in London, engineers are installing a whopping 81 escalators." "But to fit so many, some over 200 feet in length and weighing almost 50 tons, project manager Jules Boyd and his team of engineers must create their own engineering firsts." "Here, you see, this is the escalator that all of the passengers that will use Whitechapel station will come down this, and it's actually very steep, as you can see." "Hanging from the rails embedded into the tunnel roof, this specially adapted machine excavates this vast cavern, but instead of digging from the top down in the usual way, limited access from the street means the spider-like machine" "must claw its way upwards." "This is quite unique." "This is the first escalator where the tunnel was done uphill." "I'm not aware of that ever being done anywhere in this country before." "It's very difficult to do because everything is at 30 degrees." "It's quite an art to see." "Because of the dedication of those building them, the 8,200 feet of new escalators will deliver 200 million passengers each year to the platforms below." "The unprecedented and ambitious crossrail project is rewriting the rules of underground construction." "When you look at it now, it's amazing to think that, in a couple of years' time, this will be open, the Elizabeth line." "It'll be up and running and operational." "With over 100 million working hours already completed, the largest construction project in Europe is a testament to the inspirational innovations of the past and the ingenuity of those building it today." "To see the whole process from start to finish has just been remarkable." "I mean, I'm getting towards the end of my career." "I doubt I'll do another one of these, but you never know." "Opening in 2018, the enormously complex and groundbreaking crossrail remains on track and is succeeding in making the impossible possible." "If you think of all the thousands of people that worked on this project, the billions of pounds that were spent constructing it, the challenges we've managed to overcome," "I think it'll be a fantastic achievement." "It's a real feat for the U.K. Rail industry."