Narrator: TODAY
ON "IMPOSSIBLE ENGINEERING," THE RION-ANTIRION BRIDGE -- A COLOSSAL STRUCTURE BUILT IN
THE HEART OF AN EARTHQUAKE ZONE. SPANNING 2 MILES
ACROSS OPEN WATER, IT TOOK REVOLUTIONARY
ENGINEERING... ...AND A LOOK BACK AT SOME
HARD LESSONS FROM THE PAST... THE ENERGY RELEASE WAS MASSIVE, AND NOW THE SPECIMEN HAS
JUST CATASTROPHICALLY FAILED. Narrator: ...TO MAKE
THE IMPOSSIBLE...POSSIBLE. --<font color="#FFFF00"> Captions by VITAC --</font><font color="#00FFFF">
www.vitac.com</font> CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS AUGUST 2004,
THE RION-ANTIRION BRIDGE OPENS TO TRAFFIC
FOR THE FIRST TIME. IT'S AN ENGINEERING MASTERPIECE
OF THE MODERN AGE. THIS MASSIVE STRUCTURE SPANS ALMOST 2 MILES ACROSS
THE GULF OF CORINTH IN GREECE. IT BOASTS THE LONGEST
FULLY SUSPENDED DECK AND DEEPEST FOUNDATION PIERS
OF ANY BRIDGE ON EARTH. FOR CHIEF ENGINEER
PANAYOTIS PAPANIKOLAS, IT WAS THE PROJECT
OF A LIFETIME... ...BUT FOR CENTURIES, BUILDING A BRIDGE ACROSS THE
GULF OF CORINTH WAS JUST A DREAM DUE TO A LONG LIST
OF ENVIRONMENTAL CHALLENGES. BUT WIND ISN'T THE ONLY THREAT
TO THE BRIDGE. THE TWO LAND MASSES ON EITHER
SIDE OF THE GULF OF CORINTH ARE CONSTANTLY DRIFTING APART. THIS, ALONG WITH FREQUENT
EARTHQUAKES, HIGH WINDS, AND DEEP WATER MEANT THAT BUILDING A BRIDGE ACROSS THE
GULF WOULD BE A DAUNTING TASK... ...BUT THE NEED FOR A SAFE
CROSSING WAS DESPERATE. THE PERILOUS WATERS
OF THE GULF OF CORINTH OFTEN MADE FERRY CROSSINGS
IMPOSSIBLE AND CUT THE PENINSULA OFF
FROM IMPORTANT SERVICES. SO IN THE 1990s,
THE GOVERNMENT EMBARKED ON ONE OF THE MOST AMBITIOUS
ENGINEERING PROJECTS IN MODERN HISTORY. THE FIRST CHALLENGE
WAS TO DESIGN A BRIDGE THAT COULD SPAN THE ALMOST 2-MILE GAP
ACROSS THE GULF OF CORINTH. THE DISTANCE WAS TOO GREAT
FOR A SINGLE-SPAN BRIDGE, SO ENGINEERS HAS TO BUILD
SUPPORT TOWERS IN WATER THAT'S OVER 200 FEET DEEP. TO OVERCOME
THE WATER-DEPTH ISSUE, PANAYOTIS
AND HIS FELLOW ENGINEERS WOULD NEED TO LOOK TO HISTORY'S GREAT ENGINEERING
INNOVATIONS FOR THE SOLUTION. BUILDING IN WATER
HAS ALWAYS BEEN A CHALLENGE. EARLY BUILDERS RELIED ON
CONVENIENTLY PLACED ROCKS FOR THE FOUNDATION
OF THEIR STRUCTURES. FINE FOR LIGHTHOUSES,
USELESS FOR BRIDGE BUILDING. CREATING ARTIFICIAL ISLANDS WAS TIME-CONSUMING AND
IMPRACTICAL IN DEEP WATER. IN THE 19th CENTURY, PRESSURIZED
STRUCTURES CALLED CASE-INS WERE DEVELOPED TO CREATE
UNDERWATER BUILDING SITES. BUT THEY WERE DIFFICULT
TO BUILD... AND DANGEROUS. FORTUNATELY,
IN THE 20th CENTURY, A NEW TECHNIQUE WAS
ON THE HORIZON. IN THE 1940s,
ENGINEER GUY MAUNSELL CAME UP WITH A SOLUTION THAT FINALLY CONQUERED THE
CHALLENGE OF BUILDING AT SEA. PROFESSOR LUKE BISBY IS HEADING
FAR OUT INTO THE ENGLISH CHANNEL TO SEE THE REMAINS OF GUY MAUNSELL'S BOLD CREATION
FIRSTHAND. MAUNSELL'S INFLUENCE
ON CONTEMPORARY ENGINEERING I DON'T THINK
REALLY CAN BE OVERSTATED. THIS WAS REALLY THE FIRST TIME THAT THIS HAD EVER BEEN
ATTEMPTED, AND SO IT WAS REALLY QUITE
A DARING FEAT OF ENGINEERING. Narrator:
MAUNSELL'S INNOVATION WAS TRIGGERED
BY THE SECOND WORLD WAR. IT BECAME CLEAR THE RIVER THAMES
WAS A PRIME TARGET FOR GERMAN BOMBERS
DURING THE WAR. THE GERMANS WANTED
TO DESTROY LONDON'S DOCKS AND LAY MINES
TO DISRUPT ALLIED SHIPPING. SO MAUNSELL CAME UP
WITH A RADICAL NEW DESIGN FOR OFF-SHORE SEA DEFENSE... ...NAVAL FORTS CONSISTING OF TWO
80-FOOT HIGH CONCRETE TOWERS EACH CONTAINING FOUR FLOORS
OF ACCOMMODATIONS TOPPED WITH A GUN DECK. BUT THE INGENIOUS PART
OF MAUNSELL'S DESIGN WASN'T THE LAYOUT OF THE FORT -- IT WAS HOW IT WOULD
BE CONSTRUCTED AND DEPLOYED AT SEA. KNOCK JOHN HERE WAS TOWED OUT
3 TO 6 MILES FROM WHERE
IT WAS CONSTRUCTED ON LAND, AND THEN IT WAS SUNK IN PLACE
EXACTLY WHERE YOU SEE IT. Narrator: MAUNSELL DESIGNED
THE BASES OF HIS FORTS AS HUGE HOLLOW CONCRETE BARGES. DESPITE THEIR ENORMOUS WEIGHT, THEY HAD ENOUGH BUOYANCY
TO FLOAT. Dr. Bisby:
MAUNSELL BUILT THE FORTS ON TOP OF THESE
LARGE CONCRETE BARGES AND THEN CALCULATED HOW LARGE
THE BARGES NEEDED TO BE IN ORDER TO HOLD
THE WEIGHT OF THE FORT SO THEY COULD BE TAKEN OUT
AND THEN SUNK IN PLACE. Narrator: THE MASSIVE
4-1/2 TON CONCRETE FORTS WERE CONSTRUCTED IN A DRY DOCK, THEN TOWED OUT TO SEA WITH
A 100-MAN CREW ALREADY ON BOARD. Dr. Bisby: WHEN THEY HAD IT IN
THE PLACE WHERE THEY WANTED IT, THEY ESSENTIALLY JUST PULLED OUT
A STOPCOCK AT ONE END AND LET THE WATER FLOW IN. AS THE WATER WAS FLOWING IN, THE BARGE STARTED TO LIST
IN THE WATER. EVENTUALLY, THE NOSE DIPPED
UNDER THE WATER. ALL 100 MEN WERE HANGING ON AS THE FORT WAS SINKING
AT 35 DEGREES. Narrator:
DESPITE THE ROUGH SUBMERSION, MAUNSELL'S GROUNDBREAKING DESIGN
WORKED PERFECTLY. THE BOTTOM OF THE BARGE
BASICALLY FILLED UP WITH WATER, AND EVENTUALLY THE ENTIRE BARGE
SUNK TO THE BOTTOM AND FLATTENED OUT. Narrator: MAUNSELL'S FORTS
HELPED BRITISH FORCES SHOOT DOWN 22 ENEMY AIRCRAFT
AND 30 FLYING BOMBS. THEY PROTECTED LONDON
FROM ATTACK AND MADE ENGINEERING HISTORY. Dr. Bisby: THE INFLUENCE OF THIS
TYPE OF CONSTRUCTION YOU CAN SEE IN ALL DIFFERENT FACETS
OF ENGINEERING TODAY. YOU CAN SEE IT IN THE
OFF-SHORE-OIL-AND-GAS INDUSTRY WITH OIL PLATFORMS. YOU CAN SEE IT BEING USED AS
FOUNDATIONS FOR WIND TURBINES. AND, OF COURSE,
YOU CAN SEE IT BEING USED AS A WAY OF PLACING FOUNDATIONS FOR LARGE BRIDGE STRUCTURES
AROUND THE WORLD. Narrator: BUT THE MOST
IMPRESSIVE USE OF MAUNSELL'S REVOLUTIONARY
FLOATING CONCRETE DESIGN IS AT THE RION-ANTIRION BRIDGE. Narrator:
THE RION-ANTIRION BRIDGE SPANS AN INCREDIBLE 2 MILES ACROSS THE DEEP WATERS
OF THE GULF OF CORINTH. TO SUPPORT
THIS MASSIVE STRUCTURE, ENGINEERS USED PRINCIPLES FIRST EXPLOITED BY GUY MAUNSELL
IN THE 1940s AND SUPER-SIZED THEM. IN 1998, CONSTRUCTION BEGINS
ON 4 ENORMOUS PIER FOUNDATIONS. EACH ONE IS LARGER
THAN A FOOTBALL FIELD AND WEIGHS ALMOST 80,000 TONS. THE HOLLOW PIER FOOTINGS
ARE BUILT IN A DRY DOCK JUST AS GUY MAUNSELL DID BUT ON A SCALE
HE COULDN'T HAVE IMAGINED. BEFORE THE FOOTINGS CAN BE TAKEN
OUT INTO THE GULF OF CORINTH, ENGINEERS NEED A SOLUTION
TO A SERIOUS PROBLEM -- A PROBLEM MAUNSELL
NEVER HAD TO DEAL WITH. THE GULF OF CORINTH
LIES IN THE HEART OF ONE OF THE MOST ACTIVE
SEISMIC ZONES IN THE WORLD. IN AN EARTHQUAKE, THE SOFT
SEAFLOOR WOULD LIQUIFY CAUSING THE PIERS TO SINK
AND THE BRIDGE TO COLLAPSE. UNLESS AN ANSWER WAS FOUND,
THE PROJECT WAS OVER. THE ENGINEERS CAME UP
WITH A RADICAL SOLUTION. THEY WOULD DRIVE HUNDREDS OF
LONG TUBES DEEP INTO THE SOIL WHERE THE FOUR PIERS WILL SIT. THIS INGENIOUS IDEA
STABILIZED THE SOFT SEAFLOOR. BRIDGE FOOTINGS ARE USUALLY ANCHORED DIRECTLY
INTO THE GROUND. BUT FOR THE RION-ANTIRION, THEY WERE PLACED ON TOP
OF A 10-FOOT LAYER OF GRAVEL. THIS ALLOWED THE FOOTINGS
TO SHIFT WITH THE EARTH DURING AN EARTHQUAKE. WITH A SOLUTION
TO THE EARTHQUAKE PROBLEM, THE ENGINEERS ARE NOW READY
TO BEGIN ONE OF THE MOST AUDACIOUS PARTS
OF THE BUILD... ...MANEUVERING
THE HALF-CONSTRUCTED PIERS INTO THE GULF. ENGINEERS CONTINUED TO BUILD UP
THE MASSIVE STRUCTURES WHILE THEY WERE STILL FLOATING. EACH LAYER OF HEAVY CONCRETE
THAT WAS ADDED SUNK THE PIER FURTHER DOWN, PUSHING IT CLOSER
TO ITS FINAL RESTING PLACE 200 FEET BELOW ON THE SEAFLOOR. THE END RESULT WAS FOUR ENORMOUS
HOLLOW FOUNDATION PIERS. THEY'RE THE FIRST
OF THEIR KIND -- A SERIES OF MASSIVE
CONCRETE UNDERWATER CAVERNS. THE PIER FOOTINGS
FOR THE RION-ANTIRION CAN SURVIVE AN EARTHQUAKE, BUT WHAT ABOUT ITS NEARLY
2-MILE LONG SUSPENDED DECK? THE BUILDERS OF THIS MASSIVE
STRUCTURE WILL NEED TO PRODUCE EVEN MORE
IMPOSSIBLE ENGINEERING. Narrator: THE RION-ANTIRION
BRIDGE IN GREECE IS A MODERN ENGINEERING MARVEL. OVER 11 MILLION CUBIC FEET
OF CONCRETE, MORE THAN 100,000 TONS OF STEEL,
AND 39 MILES OF CABLING MAKE UP THE LONGEST FULLY
SUSPENDED CABLE-STAYED BRIDGE ON THE PLANET. PANAYOTIS PAPANIKOLAS
AND HIS FELLOW ENGINEERS HAD TO OVERCOME
A LONG LIST OF OBSTACLES BEFORE THEIR DREAM OF A BRIDGE SPANNING
THE GULF OF CORINTH COULD BE REALIZED. THE GULF OF CORINTH IS ONE OF THE BUSIEST
TRADE ROUTES IN EUROPE. ITS SHIPPING LANES
CANNOT BE DISRUPTED. TO DESIGN A BRIDGE
CAPABLE OF SPANNING THIS GAP WITHOUT INTERFERING
WITH SHIPPING, ENGINEERS WOULD NEED TO TURN TO THE GREAT INNOVATORS
OF THE PAST FOR INSPIRATION. IT WAS THE ROMANS WHO FIRST
ENGINEERED SOLID BRIDGES USING STONE AND A SIMPLE BUT
REVOLUTIONARY SHAPE -- THE ARCH. HOWEVER, THE WIDER THE GAP, THE MORE ARCHES WERE NEEDED AND
THE HEAVIER THE BRIDGE BECAME. FOR HUNDREDS OF YEARS, INCA
COMMUNITIES IN THE HIGH ANDES CROSSED GORGES USING
SUSPENDED WOODEN WALKWAYS. IT'S SAID THAT 16th-CENTURY
SPANISH CONQUISTADORS ARRIVING IN PERU
LOOKED IN AMAZEMENT AND FEAR AT THE SWAYING BRIDGES
THAT COULD BREAK AT ANY MOMENT. IT WASN'T UNTIL 1826
THAT A BRILLIANT ENGINEER UTILIZED NEW BUILDING MATERIALS
AND A NEW APPROACH TO CHANGE THE BRIDGE GAME
FOREVER. THE MENAI SUSPENSION BRIDGE IS THE ULTIMATE ACHIEVEMENT
OF THOMAS TELFORD -- ONE OF BRITAIN'S FINEST
CIVIL ENGINEERS. TELFORD WAS
AN ACCOMPLISHED ENGINEER. OF COURSE, AT THIS STAGE, HE HAD DESIGNED CANALS
AND ROADS AND BRIDGES. HE HAD NEVER BUILT ANYTHING
ON THIS SCALE BEFORE, AND SO, THIS BRIDGE WAS TO BE
REALLY HIS GREATEST CHALLENGE. Narrator: THE MENAI STRAIT
SEPARATES MAINLAND WALES FROM THE ISLAND OF ANGLESEY. CENTURIES AGO, BRIDGING IT
WOULD HAVE BEEN IMPOSSIBLE. A TRADITIONAL ROMAN ARCH DESIGN
WOULD NOT ONLY BE ENORMOUS, IT WOULD BLOCK THE PASSAGE OF
TALL SHIPS ALONG THE WATERWAY. Dr. Bisby: IMAGINE THIS
AS BEING THE STRAIT HERE, AND THESE ARE THE VALLEY WALLS
ON EITHER SIDE OF THE STRAIT. BASICALLY,
YOU CUT YOUR BITS INTO SHAPE, AND YOU THEN HAVE TO GRADUALLY
BUILD YOUR ARCH, ADDING THE BITS OF THE ARCH
AS YOU GO. AND IF YOU IMAGINE THAT AS NOW
BEING THE COMPLETED ARCH -- AND WE HAVE OUR LOAD
COMING ALONG HERE -- YOU CAN SEE THAT THE COMPRESSION
FORCES THAT COME FROM THAT CAR FLOW DOWN THROUGH THE VARIOUS
SECTIONS OF THE ARCH AND INTO THE ABUTMENTS
ON EITHER SIDE OF THE VALLEY. NOW, THE PROBLEM
THAT TELFORD FACED WAS THAT
AS YOU'RE BUILDING AN ARCH, YOU WOULD HAVE TO HAVE
SOME SUPPORTS DOWN HERE UNDERNEATH THE MIDDLE
OF THE ARCH SO THAT AS YOU'RE BUILDING IT, THE BLOCKS DON'T FALL
INTO THE STRAIT. AND THAT WOULD REQUIRE
SOME SCAFFOLDING. AND THIS WAS JUST NOT ACCEPTABLE
TO THE ADMIRALTY AT THE TIME BECAUSE THIS IS A VERY BUSY
SHIPPING CHANNEL AND THEY REQUIRED
100 FEET OF CLEARANCE ABOVE THE HIGH-WATER MARK. AND THAT LED TELFORD
TO HAVE TO CONSIDER SOMETHING THAT COULD GIVE HIM
A VERY LONG CLEAR-SPAN WITH NO SUPPORTS IN THE WATER
EVEN DURING CONSTRUCTION. Narrator: TELFORD'S SOLUTION WAS THE WORLD'S FIRST MAJOR
LONG-SPAN SUSPENSION BRIDGE. FOR A SUSPENSION BRIDGE, WE NEED
TWO VERY STRONG ABUTMENTS, AND THEN YOU NEED TWO TOWERS. AND THEN WHAT YOU DO IS,
ONCE YOU'VE BUILT YOUR TOWERS, YOU TAKE A CABLE
LIKE THESE GUYS, AND YOU STRING THESE
UP AND OVER THE TOWERS. AND THEN YOU DROP HANGER CABLES
DOWN FROM THE MAIN CABLES AND THEN PUT YOUR BRIDGE DECK
IN PLACE. AND THEN ONCE YOUR BRIDGE
IS COMPLETED, IF YOU HAVE A LOAD THAT COMES
ALONG -- SAY OUR CAR HERE -- IT COMES ALONG, AND NOW WHEN THE LOAD GETS OUT
NEAR THE MIDDLE OF THE SPAN, THE LOAD FROM THE CAR
THEN GETS TRANSFERRED UP THROUGH THE HANGER CABLES INTO THE MAIN CABLE
UP OVER THE TOWER. THE TENSION IN THAT CABLE GETS ANCHORED
IN THESE STRONG ABUTMENTS, AND THE COMPRESSION FORCE HERE GOES DOWN INTO THE FOUNDATIONS
IN THE BEDROCK. THAT'S ESSENTIALLY HOW
A SUSPENSION BRIDGE WORKS LIKE THIS BEAUTIFUL BRIDGE
WE HAVE HERE. Narrator:
TELFORD'S SUSPENDED DECK WAS A STROKE
OF ENGINEERING GENIUS. THE KEY ADVANTAGES
OF A SUSPENSION BRIDGE ARE THAT YOU CAN SPAN
LONG DISTANCES WITH NO SUPPORTS
BELOW THE BRIDGE DECKS. SO YOU CAN GET VERY LONG,
CLEAR, UNSUPPORTED SPANS BECAUSE ALL OF THE SUPPORT IS COMING
FROM THE SUSPENDING CABLES AND THE MAIN CABLES
UP ABOVE YOU. SO BELOW THE BRIDGE DECK, THERE'S ABSOLUTELY
NO OBSTRUCTIONS, WHICH IN A STRAIT IS OBVIOUSLY
A VERY IMPORTANT THING. Narrator: A SUSPENDED BRIDGE
WAS THE OBVIOUS SOLUTION FOR PAPANIKOLAS
AND HIS FELLOW ENGINEERS IN THE GULF OF CORINTH, BUT THEY WOULD HAVE TO DO IT
ON A MUCH LARGER SCALE. THE RION-ANTIRION
WOULD NEED TO BE AN INCREDIBLE SEVEN TIMES LONGER THAN THE MENAI
SUSPENSION BRIDGE. UNLIKE THE MAIN ANCHORED CABLES
OF TELFORD'S SUSPENSION BRIDGE, THIS CABLE-STAYED DESIGN
WOULD USE INDIVIDUAL CABLES RADIATING FROM 4 HUGE PYLONS
SPACED 1,600 FEET APART. EACH CABLE SET WOULD SUPPORT
A 40-FOOT SECTION OF THE BRIDGE'S DECK. IN 2003, DECK BUILDING BEGINS. EACH SECTION IS FLOATED OUT
INTO THE GULF OF CORINTH AND ATTACHED TO EITHER SIDE
OF A PYLON UNTIL THE DECKS MEET. THIS MASSIVE OPERATION TOOK
MORE THAN A YEAR TO COMPLETE. JUST AS THEY HAD TO DO
FOR THE BRIDGE'S PIER FOOTINGS, DESIGNERS HAD TO ENSURE THE DECK
COULD SURVIVE AN EARTHQUAKE IN ONE OF THE MOST ACTIVE
SEISMIC ZONES IN THE WORLD. EXPANSION JOINTS
ALLOW THE DECK TO STRETCH AS THE TWO LAND MASSES ON EITHER
SIDE SLOWLY DRIFT APART. BUT PROTECTING IT
AGAINST A MASSIVE EARTHQUAKE WILL REQUIRE
A GROUNDBREAKING NEW APPROACH. INSTEAD OF RESTING
ON THE FOUNDATION PIERS, THE DECK HANGS JUST ABOVE CREATING A SINGLE
1-1/2 MILE LONG, FULLY SUSPENDED FLOATING DECK. WHEN AN EARTHQUAKE STRIKES, FLEXIBILITY WILL BE KEY
TO THE BRIDGE DECK'S SURVIVAL. THE PIERS CAN MOVE
ON THEIR FOUNDATIONS. AND IF THE DECK WAS ATTACHED
WHEN THIS HAPPENED, IT WOULD BUCKLE AND BREAK. BUT IT'S ALSO IMPORTANT
THAT THE DECK DOESN'T SWAY DURING THE FREQUENT HIGH WINDS EXPERIENCED
IN THE GULF OF CORINTH. ENGINEERS HAD TO ENSURE RIGIDITY
IN NORMAL CONDITIONS BUT FLEXIBILITY IN THE EVENT
OF AN EARTHQUAKE. THEIR SOLUTION -- THE WORLD'S
BIGGEST SHOCK ABSORBER. IF THE BRIDGE
BEGINS MOVING ERRATICALLY, A FUSE BREAKS, SENDING THE
MASSIVE DAMPERS INTO ACTION. THIS QUAKE-BUSTING DESIGN
PROVED ITS WORTH FOUR YEARS AFTER THE BRIDGE
OPENED WHEN A 6.4-SCALE EARTHQUAKE
HIT THE RION-ANTIRION IN 2008. THE INNOVATIVE DAMPING SYSTEM
KICKED INTO ACTION SAVING THE BRIDGE FROM DISASTER. BUT EARTHQUAKES
AREN'T THE ONLY NATURAL FORCES THAT ENGINEERS
WILL NEED TO OVERCOME. TO ENSURE
THE RION-ANTIRION'S SURVIVAL, THEY WILL NEED
TO TAKE A LOOK BACK OF SOME OF HISTORY'S GREAT
ENGINEERING CATASTROPHES. Narrator: DESIGNERS
OF THE ALMOST 2-MILE LONG RION-ANTIRION BRIDGE FACED
HUGE ENVIRONMENTAL CHALLENGES. IN ONE OF THE MOST SEISMICALLY
ACTIVE REGIONS IN EUROPE, CUTTING-EDGE TECHNOLOGY
WAS DEVELOPED TO PROTECT THE BRIDGE
FROM EARTHQUAKES. BUT THE BRIDGE FACES ANOTHER EQUALLY DESTRUCTIVE
ENVIRONMENTAL THREAT THAT ITS ENGINEERS
MUST OVERCOME. TO PROTECT THIS MASSIVE
STRUCTURE FROM WIND, ENGINEERS WILL NEED TO TAKE
A LESSON FROM THE HISTORY BOOKS. WHEN THE TACOMA NARROW
SUSPENSION BRIDGE OPENED NEAR SEATTLE IN JULY 1940, IT WAS THOUGHT TO BE AT
THE FOREFRONT OF BRIDGE DESIGN. BUT IT WASN'T LONG
BEFORE THE BRIDGE GOT THE NICKNAME
"GALLOPING GERTIE." THERE WAS CLEARLY
A VERY BIG PROBLEM. JUST FOUR MONTHS AFTER OPENING, THE BRIDGE'S TWISTING MOTION
BECAME SO VIOLENT, IT SUFFERED
A CATASTROPHIC FAILURE... ...CRASHING ALMOST 200 FEET
INTO THE WATER BELOW. AN INVESTIGATION FOUND THAT THE RELATIVELY LIGHT
40-MILE-PER-HOUR WIND WAS HITTING THE SOLID EDGES
OF THE DECK, CREATING AN UNSTABLE OSCILLATION
THAT FED OFF ITSELF, AMPLIFYING TO THE POINT
OF DISASTER. THE WIND CONDITIONS ARE FAR MORE
SEVERE IN THE GULF OF CORINTH. THE MOUNTAINOUS LANDSCAPE
CREATES A FUNNEL, WHERE WINDS OF 70 MILES PER HOUR
ARE COMMON. THE AERODYNAMICS OF THE BRIDGE
DECK ARE A CRUCIAL ELEMENT. THE FAIRINGS SAFEGUARD THE DECK FROM GUSTS
OF OVER 150 MILES PER HOUR, BUT THE MASSIVE CABLES
HOLDING UP THE DECK ALSO NEED TO BE STRONG ENOUGH
TO SURVIVE EXTREME WIND GUSTS. THE DESIGNERS
OF THE RION-ANTIRION LOOKED TO AN ENGINEERING MARVEL
CREATED YEARS AGO FOR THE SOLUTION -- ONE THAT CONQUERED A CHALLENGE
ONCE THOUGHT TO BE IMPOSSIBLE. IN THE SECOND HALF
OF THE 19th CENTURY, THE GROWTH OF NEW YORK CITY WAS BEING STUNTED BY THE LIMITS
OF THE EAST RIVER. AT THAT TIME,
THE ONLY WAY FOR PEOPLE TO CROSS FROM BROOKLYN
TO MANHATTAN WAS BY FERRY. YOU SEE HERE MANHATTAN TO MY
LEFT AND BROOKLYN TO MY RIGHT. AT THE TIME, YOU COULD IMAGINE
JUST A RIVER TEEMING WITH BOATS. Narrator: BUT IN 1867,
BOAT TRAFFIC GROUND TO A HALT. Brugger: A COLD SPELL ACTUALLY
FROZE THE EAST RIVER OVER AND ESSENTIALLY HALTED COMMERCE BECAUSE YOU COULD WALK ACROSS
THE EAST RIVER AT THE TIME ON THE ICE,
BUT YOU COULDN'T ACTUALLY TRADE. SO IT WAS AT THAT POINT WHEN
VOICES REALLY KIND OF MOUNTED DEMANDING A PERMANENT KIND OF
STRUCTURAL CONNECTION BETWEEN THE TWO CITIES
WITH A BRIDGE TO HAVE THIS LASTING CONNECTION SO THAT YOU COULD HAVE RELIABLE
TRANSPORTATION AND TRADE. Narrator:
THE MAN GIVEN THE JOB WAS GERMAN-BORN ENGINEER
JOHN AUGUSTUS ROEBLING, AND WHAT HE DESIGNED STILL
INSPIRES ENGINEERS TODAY -- THE BROOKLYN BRIDGE. Brugger: JUST THE CONCEPT
OF ACTUALLY SPANNING OVER SUCH A LONG DISTANCE
AT SUCH A HEIGHT WAS EARTH-SHATTERING. NO BRIDGE HAD BEEN BUILT
EVEN CLOSE TO THIS SPAN. Narrator: THE BROOKLYN BRIDGE
SPANS OVER A MILE. IT WAS MADE POSSIBLE
BY ROEBLING'S USE OF A REVOLUTIONARY
NEW MATERIAL...STEEL. Brugger: JUST THINKING
OF ACTUALLY BUILDING A BRIDGE NOT OF MASONRY AS WE'D FIND IN KIND OF
TRADITIONAL EUROPEAN STYLE, BUT SAYING, "WE HAVE THIS NEW
MATERIAL -- STEEL -- WE WILL BUILD THE ENTIRE DECK
AND THE CABLES OF STEEL." THIS IS AN ABSOLUTE
ENGINEERING MARVEL. Narrator:
STEEL IS STRONGER, LIGHTER, AND MORE FLEXIBLE THAN IRON. ROEBLING USED THIS NEW MATERIAL FOR THE BRIDGE'S FOUR
MASSIVE SUSPENSION CABLES. HE BUNDLED HUNDREDS OF PARALLEL
STEEL WIRES TOGETHER, CREATING SUPER-STRONG
AND SUPER-SAFE CABLES. ENGINEER ADRIAN BRUGGER DEMONSTRATES JUST HOW MUCH SAFER
ROEBLING'S DESIGN IS AT COLUMBIA UNIVERSITY'S
ENGINEERING TESTING LAB. Brugger: THIS CABLE IS MADE UP
OF ACTUALLY INDEPENDENT AND SMALL 5-MILLIMETER
CIRCULAR WIRES. IN THIS CASE,
THERE'S 9,000 WIRES. THOSE WIRES ARE THEN GROUPED
INTO WHAT WE CALL STRANDS. YOU ACTUALLY TAKE THOSE AND YOU
COMPACT THOSE INTO THE CABLE. THIS IS KIND OF A HUGE LEAP FROM
THE TECHNOLOGY WE HAD BEFORE. BECAUSE BEFORE WHAT WE HAD WAS MORE OR LESS
SERIALIZED SYSTEMS, SUCH AS CHAINS
OR THESE LARGE I-BARS. WHERE IF ONE
OF THESE I-BARS FAILED, THEN GENERALLY THAT MEANT THAT
THE ENTIRE BRIDGE FAILED. IF ONE OF THESE WIRES HAPPENS
TO BE BAD OR HAS A CRACK IN IT, THEN THE ENTIRE CABLE STILL
HAS 8,999 OTHER INTACT WIRES. Narrator:
ADRIAN COMPARES THE SYSTEM
USED ON THE BROOKLYN BRIDGE TO THOSE THAT CAME BEFORE IT
USING A GIANT UNIVERSAL TESTER. AND MORE OR LESS,
A UNIVERSAL TESTING MACHINE JUST MEANS THAT IT'S A MACHINE
THAT IS BUILT TO CRUSH THINGS AND RIP THEM APART. Narrator: FIRST TO BE TESTED --
A SOLID STEEL BAR. Brugger:
THIS WOULD BE VERY SIMILAR TO WHAT YOU WOULD HAVE
ON AN OLD BRIDGE -- PRE-BROOKLYN BRIDGE FOR EXAMPLE. Narrator: THE STEEL BAR HAS BEEN
WEAKENED AT A SPECIFIC POINT AND WILL BE STRETCHED
UNDER MASSIVE TENSION TO SIMULATE A BRIDGE FAILURE. SO, WE EXPECT THIS BAR TO FAIL
AT AROUND A GOOD 200 TONS. RIGHT NOW, YOU CAN SEE
THAT THE NECKING IS STARTING AT ABOUT A QUARTER
UP FROM THE REDUCED SECTION, SO EXACTLY
WHERE WE WANTED IT. AND IT'LL BECOME MORE
AND MORE PRONOUNCED KIND OF AS WE SEE IT NOW. THE ENERGY RELEASE WAS MASSIVE, AND NOW THE SPECIMEN HAS
JUST CATASTROPHICALLY FAILED. IT'S BROKEN. Narrator: SUCH AN EXPLOSIVE
FAILURE COULD RESULT IN THE COLLAPSE
OF A WHOLE BRIDGE AS TRAGICALLY HAPPENED
WITH SILVER BRIDGE IN OHIO, CAUSING THE LOSS
OF DOZENS OF LIVES. NEXT, ADRIAN TESTS
ROEBLING'S STEEL CABLE DESIGN. AS IT'S STRETCHED,
HE SUBJECTS IT TO EXTREME HEAT TO WEAKEN IT SIMULATING A FAIL. SO, WE ARE SEEING THIS CASCADING
FAILURE RIGHT NOW. YOU CAN SEE EACH WIRE IS ACTUALLY BREAKING ONE
AFTER ANOTHER. IT'S NOT JUST THIS ONE
CATASTROPHIC FAILURE BUT RATHER THIS CASCADE. Narrator:
WHEN THE CABLE STARTS TO FAIL, THE REMAINING WIRES
TAKE UP THE LOAD. EVEN IF ALL THE WIRES FAIL, THE ENERGY RELEASED IS GRADUAL
RATHER THAN ONE HUGE EXPLOSION. SO, WHAT YOU SAW THERE WAS,
YOU KNOW, EXACTLY WHY THE SUSPENSION BRIDGE WIRES
ARE SUCH A GREAT SOLUTION. BUT YOU CAN SEE
THAT YOU DIDN'T HAVE THIS ONE CATASTROPHIC EXPLOSION
AND JUST FAILURE OF THE MEMBER BUT RATHER EACH ONE
OF THESE WIRES ACTUALLY BROKE. Narrator: STEEL TECHNOLOGY
ENABLED JOHN ROEBLING TO DESIGN WHAT WAS AT THE TIME
THE WORLD'S LONGEST AND STRONGEST BRIDGE
AND AN ENGINEERING MASTERPIECE. Brugger:
THIS BRIDGE WOULD ECLIPSE EVERY OTHER STRUCTURE
IN THE ENTIRE AMERICAS. IT WOULD BE THE TALLEST
STRUCTURE ANYWHERE. SO JUST A PERSON ACTUALLY
STANDING ON THE TOWER WOULD BE ON ESSENTIALLY THE FIRST SKYSCRAPER
IN THE UNITED STATES. Narrator: THE DESIGNERS
OF THE RION-ANTIRION BRIDGE WILL NEED TO SUPER-SIZE
THE REVOLUTIONARY IDEAS OF JOHN ROEBLING
AND THE BROOKLYN BRIDGE... THIS TYPE OF OSCILLATION WOULD BE VERY WORRYING
TO THE DESIGNERS. THE STRUCTURE COULD COLLAPSE DUE
TO OSCILLATIONS SUCH AS THIS. Narrator: ...AND CREATE EVEN
MORE IMPOSSIBLE ENGINEERING. Narrator: 180 FEET
ABOVE THE GULF OF CORINTH, CUTTING-EDGE SUSPENSION
TECHNOLOGY INSPIRED BY BROOKLYN-BRIDGE
DESIGNER JOHN ROEBLING KEEPS THE ULTRA-MODERN
RION-ANTIRION BRIDGE FROM CRASHING INTO THE WATER. BUT UNLIKE NEW YORK CITY,
NEAR-HURRICANE FORCE WINDS ARE COMMON
IN THE GULF OF CORINTH, PUTTING A GREAT DEAL OF STRESS
ON THE CABLES. AT A WIND-TUNNEL FACILITY,
PROFESSOR LUKE BISBY DEMONSTRATES JUST HOW
DESTRUCTIVE WIND CAN BE. ALL RIGHT, SO,
WE'RE GONNA START IT UP, AND WE'LL SEE WHAT HAPPENS. IF THIS WAS A CABLE
IN A REAL BRIDGE, THIS TYPE OF OSCILLATION WOULD BE VERY WORRYING
TO THE DESIGNERS BECAUSE WHAT THIS WOULD MEAN IS THAT THE METAL
THAT FORMS THE CABLE WOULD BE BEING STRESSED
REPEATEDLY BACK AND FORTH. AND EVENTUALLY IN A METAL CABLE,
THAT CAN LEAD TO FATIGUE, WHICH CAN CAUSE CRACKING AND, HENCE, POTENTIALLY FAILURE
OF THE STRUCTURE. SO THE STRUCTURE COULD COLLAPSE DUE TO OSCILLATIONS
SUCH AS THIS. Narrator: WHEN WIND STRIKES
A CYLINDRICAL STRUCTURE LIKE A CABLE,
IT SEPARATES, THEN REJOINS ON THE OTHER SIDE, CAUSING THE STRUCTURE
TO OSCILLATE -- A PHENOMENON
KNOWN AS VORTEX SHEDDING. VORTEX SHEDDING HAS BEEN
RESPONSIBLE FOR THE COLLAPSE OF SEVERAL CHIMNEYS AND TOWERS
OVER THE YEARS. IN 1957, BRITISH SCIENTIST
CHRISTOPHER KIT SCRUTON DISCOVERED THAT ADDING A SIMPLE
FIN TO A CYLINDRICAL STRUCTURE WOULD BREAK UP THE WIND VORTICES REDUCING THE VIBRATIONS
THAT COULD LEAD TO A COLLAPSE. HE CALLED THE FIN
A HELICAL STRAKE. JUST SEEING A LITTLE BIT OF
VIBRATION HERE -- NOT TOO MUCH. THIS IS REALLY INCREDIBLE
THAT THIS SIMPLE SPIRAL CAN COMPLETELY PREVENT
THE MOTION OF THIS SIMULATED BRIDGE CABLE. WITH THE HELICAL STRAKE, WE GET THIS DISRUPTION
OF THE FLOW PATTERN, WE INTRODUCE SOME TURBULENCE, AND BOTH THE FORMATION
OF THE VORTICES AND THE VIBRATION OF THE CABLE
BOTH STOP. THE HELICAL STRAKE
SEEMS TO BE WORKING. SINCE KIT SCRUTON
INVENTED THE HELICAL STRAKE BACK IN THE '50s AND '60s, IT'S BEEN APPLIED TO TENS
OF THOUSANDS OF STRUCTURES AND CHIMNEYS AND BRIDGES
AROUND THE WORLD AND HAS REALLY SAVED THEM FROM
POTENTIAL CATASTROPHIC COLLAPSE DUE TO WIND EFFECTS. Narrator: HELICAL STRAKES
ARE INTEGRATED INTO ALL OF THE NEARLY 40 MILES
OF CABLING ON THE RION-ANTIRION BRIDGE. THIS, COMBINED WITH
SPOILER-LIKE DECK FAIRINGS, MAKES THIS BRIDGE
ONE OF THE SAFEST ON EARTH. BUT A BRIDGE
CAN'T JUST BE FUNCTIONAL -- IT HAS TO BE BEAUTIFUL. SO ONCE AGAIN, ENGINEERS WILL LOOK TO THE INNOVATIONS
OF THE PAST FOR INSPIRATION. Narrator: THE RION-ANTIRION
BRIDGE IN GREECE IS A WONDER
OF THE ENGINEERING WORLD. ITS DESIGNERS
NOT ONLY HAD TO ENSURE IT COULD SURVIVE EARTHQUAKES
AND HIGH WINDS, BUT THEY WERE ALSO FORCED
TO CONSTRUCT IT IN EXTREMELY DEEP WATER
ON UNSTABLE SOIL. UNDERWATER, THE BRIDGE MAY BE
AN ENORMOUS MASS OF CONCRETE, BUT ABOVE WATER,
IT HAS TO BE ELEGANT AND ADD TO THE GREEK LANDSCAPE
AROUND IT -- NOT SCAR IT. FINDING THE RIGHT BALANCE
BETWEEN STRENGTH AND BEAUTY WAS QUITE A CHALLENGE
FOR THE ENGINEERING TEAM -- A CHALLENGE THAT
MAY HAVE BEEN INSURMOUNTABLE HAD IT NOT BEEN FOR THE GREAT
INNOVATORS OF THE PAST. IN 1928, RENOWNED SWISS
CIVIL ENGINEER ROBERT MAILLART WON A COMPETITION
TO DESIGN A BRIDGE THAT WOULD LINK
TWO REMOTE TOWNS 300 FEET ABOVE THE SALGINA
VALLEY IN SWITZERLAND. THE RESULT --
THE SALGINATOBEL BRIDGE. DESIGNATED AN INTERNATIONAL
ENGINEERING LANDMARK, MAILLART'S BRIDGE
PROVED TO THE WORLD THAT CONCRETE COULD BE BOTH
PRACTICAL AND BEAUTIFUL. ENGINEER URS MEYER
HAS BEEN A LIFELONG FAN OF THE ICONIC STRUCTURE, BUT HE'S ABOUT TO SEE IT FROM
AN ENTIRELY NEW PERSPECTIVE. BUILDING A BRIDGE IN THIS REMOTE
PART OF EASTERN SWITZERLAND REQUIRED GREAT INGENUITY. CONCRETE IS STRONG
IN COMPRESSION, BUT REINFORCING IT
WITH STEEL BARS ALSO GIVES IT STRENGTH
IN TENSION, ALLOWING IT TO BE MANIPULATED
INTO ALMOST ANY SHAPE. MAILLART DESIGNED AN ELEGANT
THREE-PINNED HOLLOW BOX ARCH SUPPORTED BY REINFORCED
CONCRETE COLUMNS. THIS MADE THE CONCRETE
STRONG ENOUGH TO TRANSMIT THE BRIDGE LOADS
TO THE FOUNDATIONS BUT FLEXIBLE ENOUGH
TO ABSORB ANY GROUND MOVEMENT THAT COULD CAUSE DANGEROUS
CRACKS TO FORM. MAILLART'S SLEEK DESIGN ALSO
USED LESS REINFORCED CONCRETE, MAKING IT CHEAPER TO BUILD. BUT THERE WERE SOME SKEPTICS. WHEN THE SALGINATOBEL BRIDGE
OPENED IN AUGUST 1930, IT WAS HAILED AN ENGINEERING
AND ARTISTIC TRIUMPH, PROVING TO THE WORLD
THAT CONCRETE BRIDGES COULD BE BOTH FUNCTIONAL
AND BEAUTIFUL. 1,000 MILES AWAY IN GREECE,
MAILLART'S INFLUENCE CAN BE SEEN ALL OVER
THE RION-ANTIRION BRIDGE. THE FOUR REINFORCED
CONCRETE PYLONS EMBODY COST-SAVING MINIMALISM,
FLEXIBLE STRENGTH, AND ELEGANT DESIGN. 780,000 TONS OF REINFORCED
CONCRETE ENSURE THIS BRIDGE COULD SURVIVE AN EARTHQUAKE
OF 7 ON THE RICHTER SCALE. THE RION-ANTIRION BRIDGE
HAS REDRAWN THE MAP OF GREECE, AND ITS DESIGNERS
HAVE REWRITTEN THE RULES OF BRIDGE ENGINEERING FOREVER. BY MODERNIZING INNOVATIONS
OF THE PAST AND MAKING GROUNDBREAKING
DISCOVERIES OF THEIR OWN, THE ENGINEERS AND DESIGNERS
OF THIS INCREDIBLE STRUCTURE HAVE SUCCEEDED IN MAKING
THE IMPOSSIBLE POSSIBLE.
