Case Study3 - Golden Gate Bridge

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Civil Engineering, National Taiwan University, Case Study.

Transcript of Case Study3 - Golden Gate Bridge

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Golden Gate Bridge

olden Gate Bridge is on the San Francisco Bay and connects

the Golden Gate Bay on the Pacific Ocean. The bridge was

finished in 1937 and was the longest suspension bridge in the world

when finished. It is now the landmark symbol of San Francisco in

the state of California. Golden Gate Bridge connects the north of

San Francisco Peninsula to the south of Marin County, both

California State Route 1 and U.S. Route 101 pass through this bridge.

It is an important traffic route to the cities on either sides of the San

Francisco Bay.

Before Golden Gate Bridge was built, San Francisco and Marin

County mainly depended on ferries to cross the San Francisco Bay.

Many people wanted to build a bridge that crossed the ocean to

connect to San Francisco and Marin County; however, experts at that

time indicated that a bridge could not cross the 6,700 feet (2,042

G

Photo 1. Golden Gate Bridge adopted suspension design, crossing

the 2,042 meters wide San Francisco Bay.

1、 Introduction

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meters) wide strait. The weather condition of the San Francisco

Bay also hindered the building of a bridge that awaited to be

conquered: dense fogs that constantly blanketed San Francisco Bay;

gusty winds with speed reached over 60 miles per hour; forceful

swirl in the bay and the ocean passage with water depth over 150 feet

(around 500 meters) which made it difficult to cross. If were to

build a bridge, namely the Golden Gate Bridge; to cross the ocean, it

would inevitably have to overcome these natural obstacles. To the

engineering experts at that time, this was a bridge that could never be

built. According to the initial assessment by the engineers at the

San Francisco area, to build a bridge across ocean with so many

natural obstacles, it would take at least 1,000 million US dollars.

As for the estimated completion date, it would be a dream that was

impossible to come true.

Joseph Strauss was the Chief

Engineer of the Golden Gate Bridge.

When he was a student, he designed a

55 miles long (89 kilometers) railroad

bridge across the Bering Strait as his

graduate thesis. He also designed

over 400 bridges inland. Strauss has

rich experience in bridge design but he

himself never designed a “suspension

bridge”. He drew a simple

conceptual bridge design sketch in

which he installed giant steel

Photo 2

Golden Gate Bridge crosses the San

Francisco Bay, connecting San

Francisco and Marin County.

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suspended arms on each side of the strait, and used a suspended

bridge in the middle to connect to the suspended arms. Strauss

promised the local authority that he could finish such a bridge with

1.7 million US dollars. Through the advancement in metallurgy,

such a cantilever bridge was gradually accepted as a feasible concept.

Strauss spent more than 10 years to persuade the residents of the

northern California into accepting this bridge construction project.

He also recruited Charles Alton Ellis, Leon Moisseiff, and Irving

Morrow to join the Golden Gate Bridge design. Ellis and Moisseiff

together elaborated their professional engineering technique, giving

Golden Gate Bridge the precise mathematical calculation and stable

structure design. They put wind resisting technology into the

structure design, making it a suspension bridge across the strait by

ways of the modern engineering technology, successfully

counteracted the natural factors that was unfavorable to bridge

building. Irving Morrow’s design, on the other hand, made the

appearance of the Golden Gate Bridge beautiful. H coordinated the

Golden Gate Bridge with its surroundings to reflect a harmonious

beauty, whether the street lamps in the dense fog, the shape of the

bridge towers, and even the color of the Golden Gate Bridge – the

international standard orange.; these all came out of Irving Morrow’s

inspiration. The international standard orange is able to bring out

the bridge in the dense fog; this design attends to both traffic safety

and the bridge beautification. Strauss himself was not an expert to

suspension bridge, but the team he led was able to combine the

mature engineering technology and the innovative designing

perspective to create the legend of the Golden Gate Bridge. After

over 70 years of testing by the harsh weather condition, Golden Gate

Bridge is still the landmark building of San Francisco, standing firm

on the San Francisco Bay, shouldering the task of connecting the

traffic on either ends.

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2、 Structure

Many inevitable natural obstacles shall need to be overcome in

order to build such a challenging suspension bridge. How to make

this bridge firmly suspended between two distant cities across the

strait? The bridge span was itself a huge challenge to the engineering

technology of the time. Engineering team must go through

conscientious mathematical calculations to ensure the bridge structure

would not disintegrate in the strong winds, they must try different

measures to overcome the natural obstacles that lay in the bridge

construction. Golden Gate Bridge mainly depends on two stable

piers to support the bridge towers, steel cables of the bridge towers

hoist the bridge so that the bridge would not swing too much with the

constant strong winds, and can firmly take on the traffic

communication for both two islands on either side of the Golden Gate

Bridge. In the following, we will describe in detail the two most

important structures of the Golden Gate Bridge: the piers and the

Photo 3. Spectacular night view of the Golden Gate Bridge in San

Francisco.

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bridge towers.

2.1 Piers

Golden Gate Bridge began

construction in 1933 from the

pier on the Marin County end.

Originally the engineering team

planned to seek hard rock above

the water level to set up the piers;

however, geologists thought such

piers would not withstand

earthquakes. Finally Chief

Engineer Strauss agreed to

deepen the north side bridge

foundation to 100 feet below the

surface, and penetrating 35 feet

into the rock layer under the

bottom of the ocean. Pier is the

vital structure foundation of the

whole bridge, it determines

whether the Golden Gate Bridge

is capable of resisting the strong

current in the bay. Rooting the pier into the rock layer in the

bottom of the ocean is a necessary procedure as well as a crucial

engineering technology. The pier on the south side of the Golden

Gate Bridge was the most difficult construction of the whole process.

It has to be installed at the point which was 1,200 feet away from the

shore and in the depth of 100 feet below the water. Engineering

study report indicated that under such depth, the visibility underwater

was close to zero. Tidal waves, swirls and ledges et al natural

factors made the construction work exceptionally difficult. From

Photo 4. Piers were the most

difficult part in constructing the

Golden Gate Bridge; they must

withstand the impact of

earthquakes and currents.

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the overall assessment, we could understand that this would be a

tough mission. How to build the pier on the south side became a

huge test of the construction. Engineers finally made a concrete

frame with the total height at 750 feet, of which 15 feet was above

the water level, and extracted the sea water within. Construction

engineers then installed the steel bars of the pier inside the concrete

frame. Once the steel bars structure of the pier was finished,

engineers then installed pipes to inject the sea water into the frame,

allowing the sea water to run inside of the pier to offset the impact of

the waves on the pier. This would achieve a better

earthquake-proof effect.

Photo 5. Steel bars of the pier structure were built within the concrete

frame to offset the impact of waves.

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2.2 Bridge Towers

Golden Gate Bridge has two bridge towers, each at 342 meters

high, of which 227.4 meters is above the water. The height equals

to a 70 stories building and is the fourth tallest bridge tower in the

world. Two steel wires, 92.7 mm in diameter weigh 24.5 thousand

tones, are connected on top of the tower. Thousands of steel bars

connect the steel wires with the bridge. Each of these wires is 750

feet long. The main cable of the Golden Gate Bridge is 7.650 feet

long and 3 feet in diameter. Each cable is intertwined by steel wires

that is 27.252 feet long and is as thick as a pencil. Stretching all the

way from Marin County to San Francisco, this main cable holds the

bridge firmly and is also the reason why the Golden Gate Bridge

stands firm for over 7 decades. Golden Gate Bridge is able to

withstand swings at 21 feet in horizontal and 10 feet in vertical range.

This resisting range enables the bridge to stand firm in the strong

winds; it also prevents the bridge from disintegrate due to over

swinging in earthquakes. Since opening for traffic on May 27th

1937, the Golden Gate Bridge has been constantly taking the full 6

Photo 6. Golden Gate Bridge tower and connecting cables, they are the

vital structure that bear the weight of the bridge and vehicles.

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lanes load of vehicles of all sizes and pedestrians crowding the side

walks on the bridge. It went through several strong earthquakes and

remained standing in the strong winds and high tides, serving as the

major communication route for over 70 years. It proves to be a

bridge across that ocean that stands the test of time.

Photo 7. Golden Gate Bridge has two bridge towers, each at the

height of a 70 stories building.

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3.1 Joseph Strauss

Strauss was the Chief Engineer

of the Golden Gate Bridge. He was

born in Cincinnati, Ohio. His father

was a painter and writer, mother a

pianist. Strauss was a productive

engineer who designed over 400

small bridges; however, he never had

any experience in building suspension

bridges. He was not very precise

about the Golden Gate Bridge conceptual drawing and he lacked the

engineering theory concept to suspension bridge constructions. His

design sketch was not a possible concept and he needed a strong

engineering team to help him accomplish the task. He hired two

engineering mathematical experts, one was Charles Ellis and other

one was Leon Moisseiff. Ellis and Moisseiff together tailored a

precise bridge construction ratio and wind resisting structure design.

They made Golden Gate Bridge an idea that no longer existed on

papers but a practical construction plan.

Strauss later recruited Irving Morrow to help design additional

function to the bridge as well as increase the artistic level of the

bridge façade. Though Strauss was not green to suspension bridge,

as a Chief Engineer, he still needed to face problems big and small in

the construction process. Due to limited funding, he was forced to

raise money from citizens and the US troops. In addition, Strauss

respected construction safety greatly. According to the statistics,

one out of 100 workers would die during the construction. Strauss

3、 Construction Team

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considered the human lives were highly valuable and thus he

installed several safety nets in the construction sites to protect the

safety of the workers. Unfortunately, there were still 11 people

frozen to death by the sea water due to the collapsing of the steel

scaffold that went into the ocean during construction. They were

unable to be rescued by the safety nets installed by Strauss.

Strauss’s value to the construction safety also extended to the bridge

safety. “Safety” is a very important designing concept that is easily

neglected. Strauss’s team valued the bridge safety as much as he

did. From structural design to the street lamps on the bridge, the

safety of the pedestrians and the traffic were put into concern. Till

this day, the initial idea that Strauss had and his persistence on the

overall construction are still the main reasons why the Golden Gate

Bridge is recognized by the world.

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Photo 8. Golden Gate Bridge under construction: the bridge

towers.

Photo 9. Bridge towers of the Golden Gate Bridge; steel cables

connected between bridge towers.

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Photo 10. Detail structure of the Golden Gate Bridge.

3.2 Charles Alton Ellis

Ellis was a professor, structural engineer, and mathematician; he

was in charge of the Golden Gate Bridge structure. His career

background included professor at University of Michigan, Illinois, and

Purdue. He was hired as a team member to Strauss’s team mainly in

charge of the sophisticated calculation to the bridge structure. During

the process, he and Moisseiff elaborated their individual expertise to

come up with the sturdy ratio and structure for the Golden Gate Bridge.

The bridge remains standing after several earthquakes all because of

Ellis’ work. He contributed greatly to the primary public technology

and survey that he was in charge of. Strauss was afraid of the aura

was taken away by Ellis for his becoming popular, after a technical

and regulation delay, he ordered for Ellis to take a leave of absence

and handed Ellis’ work to a subordinate staff. Ellis was in concern

with the construction process and hoped to participate the building of

the bridge towers; however, before the end of his vacation, Ellis

received a telegram from Strauss, hoping him to never to return for

work. Ellis was shocked, after all, he had spent three years of his life

focusing on the building of the Golden Gate Bridge. Now he was

asked to step aside before the bridge was accomplished. This great

contributor behind the curtain was missing from the list when the

bridge was completed. However, in recent years, people gradually

noticed Ellis’ contribution to the Golden Gate Bridge, and restored him

the honor he deserved.

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3.3 Leon Moisseiff

Moisseiff graduated from University of

Columbia and received his master degree in

Civil Engineering in 1895. He promoted

all steel bridge to replace the concrete and

rock buildings of the 20th century.

Moisseiff proposed “deflection theory” that

would enable the Golden Gate Bridge to

resist the shaking of the strong winds. The

first bridge construction he ever conducted

was the Tacoma Narrow Bridge. Soon after the Tacoma Bridge was

finished, it was found to twist and distort from in the wind; four months

later, this bridge collapsed from the wind blow. Moisseiff’s reputation

was questioned and people began to doubt if the Golden Gate Bridge

would suffer the same fate as that of the Tacoma Narrow Bridge.

However, when Ellis and Moisseiff were working together, they did

consider the strong winds environment of the Golden Gate Bridge, and

putting great regards to the ratio of bridge span and width. Ellis

thought the ratio and structure design of the Golden Gate Bridge would

exempt it from the threat of collapsing like the Tacoma Narrow Bridge.

When people stand on the bridge during normal days, they would feel

the slight shaking of the bridge. This shaking is under the safe range,

unlike Tacoma Bridge that twisted severely in the wind due to

resonance. Time proves that Golden Gate Bridge indeed is capable of

withstanding the test of strong winds at the Golden Gate Bay. Though

Moisseiff contributed greatly to the Golden Gate Bridge, the failure of

the Tacoma Bridge overshadowed his contribution to other

constructions. However, it was also because of the example of a

failure bridge that people realized the importance of the bridge structure

stability and safety.

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Photo 11. Upward view of the Golden Gate Bridge Tower, the

orange color goes well with the blue sky.

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3.4 Irving Morrow

Morrow was recruited into the

Golden Gate Bridge design team by

Strauss in 1930.. Unlike Ellis and

Moisseiff that were in charge of the

bridge structure design, Morrow was

in charge of the smaller functions of

the bridge such as street lamps, rails

and pedestrians overpass, etc. What

remains the most important part of his

design work is the color of the Golden

Gate Bridge, the international

standard orange. The bridge authority at the time did not think

there was any type of red paint that could resist the high saline

weather; some people even suggested to paint the bridge with dark

grey color or the highly visible yellow or black stripes. Morrow did

not take in those suggestions. To be persistent with his idea, he

found a type of paint which made the bridge authority give in and

decided to paint the Golden Gate Bridge in the international standard

orange color. After painted international standard orange, the

Golden Gate Bridge stood out of the fog. The color served the

traffic safety purpose on one hand, and on the other hand, it made the

bridge coordinated harmoniously with its surroundings. This is

Morrow’s main contribution to the Golden Gate Bridge, his design

engraved the image of the bridge deeply in people’s mind.

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4、 Construction Obstacles

The most difficult part in building the Golden Gate Bridge,

besides the exceptional long span, was the ever changing weather in

San Francisco Bay. Overcame the natural weather factors that were

disadvantageous to bridge building was the major break through in

the Golden Gate Bridge construction history. In the following, we

will describe the obstacles during the construction of the Golden

Gate Bridge and some of the challenges that the bridge would face in

the future.

4.1 Persistently Foggy Weather

Fog often rises in San Francisco Bay, and it often comes

unexpectedly with the density that the one cannot see what is in front.

Even after the completion of the Golden Gate Bridge, because of the

Photo 12. Irving chose international standard orange that enabled

the Golden Gate Bridge to standout in the fog.

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fog, the full view of the bridge was hard to be seen. The weather in

San Francisco Bay changes to rapidly that sometimes it is covered in

dense fog and the next minute, it is sunny and clear. The fog

brought along obstacles to the building of the Golden Gate Bridge,

for example the corrosion of the steel. Fog normally carries high

saline and moisture so materials used in building the Golden Gate

Bridge had to be corrosion resisting materials; but what type of

materials were corrosion resisting at that time? Since there were no

materials that were corrosion resisting and fit for bridge building, the

strategy was to paint the bridge with corrosion resisting paints.

Morrow decided to paint the Golden Gate Bridge with international

standard orange for he wanted to use the paint to resist the steel

corrosion, and at the same time to increase the visibility of the bridge

in the fog for safety protection effects.

Photo 13. Dense fog often covers the entire Golden Gate Bridge

and brings difficulty to constructions.

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4.2 Strong Winds

The wind speed in San Francisco Bay is extremely strong that

sometimes it can reach 60 miles per hour. Even after the

completion of the bridge, one can feel the bridge slightly shaken by

the wind when standing on the bridge. How would the wind speed

affect the bridge? What are the challenges to overcome when

building bridge where the strong winds blow? In addition to

making people and vehicles on the bridge feel safe and sturdy, there

also need to prevent the bridge from disintegrate in the strong winds.

The ration of the bridge therefore has to be correctly generated

before the construction. Thanks to Ellis and Moisseiff, the

mathematical and bridge structure experts, who used sophisticated

calculations to help the bridge resist the strong winds, making the

Golden Gate Bridge to deflect slightly during the strong winds

instead of shaking violently and collapse. From completion till this

Photo 14. Golden Gate Bridge painted in international standard

orange can still be seen clearly in the midst of thick fog.

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day, the Golden Gate Bridge only shut down for three times due to

wind speed. For a ocean crossing bridge that is going to celebrate

its 70 years anniversary, the Golden Gate Bridge proves that it stands

the test of winds.

4.3. Strong Ocean Currents

The ocean current under the Golden Gate Bridge is strong and

the water is freezing cold. During the construction period, there

were 11 workers fell into the safety net that were supposed to help

them survive the fall; however, as the water was icy cold, the

workers were unfortunately frozen to death from the water. With

the current being so strong, it was also not very easy for the divers at

that time to see the conditions under the ocean. The process of the

construction thus became very dangerous, and the difficulty of the

construction also was highly elevated. In recent years, the

Managing Council of the San Francisco City has been drafting

research project to utilize the currents under the Golden Gate Bridge

current as power source for electricity, hoping to use the natural

currents to provide powers for the San Francisco residents.

However, such concept requires considering the ecological aspects of

the environment. As indicated by the energy expert of the San

Francisco Environment Department Peter O’Donnel “when fish runs

into those turning turbine blades, it would be as if inflicting hanging

on themselves; just like slices of sushi on the plate.” Therefore,

such a concept currently requires further considerations in order to be

put into practice in the future.

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5、 Challenges after Completion

5.1 Earthquakes

“Safety” has always been the primary concern when building bridges.

A strong bridge must able to withstand the test of different natural

catastrophes. “Earthquake” is a type of natural catastrophes that

directly endangers the safety of the bridges, and earthquakes happen

quite frequently in San Francisco area. Golden Gate Bridge spans

over thousand meters and the vibration during the earthquake could

easily collapse the bridge. Ellis and Moisseiff did target the bridge

width and span and perform sophisticated ration calculation; the

piers were also grounded into the rock bed at the bottom of the ocean.

In terms of earthquake proof design, since there were comprehensive

considerations during the construction, Golden Gate Bridge’s design

was far more careful than that of the nearby Bay Bridge. In 1989, a

Photo 15. The tidal

waves and currents

beneath the Golden

Gate Bridge are

very strong, making

the construction

very dangerous.

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Richter scale magnitude 7.1 Loma Prieta earthquake struck San

Francisco. Many houses and roads collapsed in the earthquake,

even the other bridge on San Francisco Bay – the Bay Bridge – was

not exempt from the earthquake and suffered from the breakage on

the bridge surface. Miraculously, the Golden Gay Bridge was

unharmed in this catastrophe. To prevent the Golden Gate Bridge

from collapsing from the strong quakes, the basic main structure of

the bridge must be maintained constantly. Several supporting

structures that could help resist the strong quakes were also added to

the bottom of the bridge. The structure ratio of the Golden Gate

Bridge itself is also a key element for resisting earthquakes.

Although Golden Gate Bridge survived several earthquakes, there is

no guarantee that the bridge will survive other even stronger quakes.

In the future, more advanced technologies should be developed for

collapse-free constructions. A good construction still requires even

more technologies after completion to extend its life span.

Photo 16. Golden Gate Bridge stood through many strong

earthquakes owing to the constant maintenance.

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5.2 Steel Corrosion

Golden Gate Bridge suspends on the San Francisco Bay; mist,

moist and strong winds are corrosive to the steel structure, causing

the paint to come off and the steel to rust that weaken the structural

support. Paint is a type of protection for the Golden Gate Bridge to

resist corrosion. The international standard orange paint is mainly

for resisting corrosion and ensuring the traffic safety in the mist; as

well as to create a harmonious beauty with the surrounding

environment. “International standard orange” is composed of red,

yellow and black colors. This color has already been the signature

color of Golden Gate Bridge and it makes the bridge remain

exceptionally beautiful in the dense fog. After the completion, the

maintenance work of the Golden Gate Bridge is also a painstaking

task. Workers must examine and replace the corroded steel or rivets

periodically, and then coating the steel with corrosion resisting paints

to extend the life of Golden Gate Bridge. Since completion, some

steel components have already been replaced with new ones but the

basic structure and the main cables of the Golden Gate Bridge have

not yet been replaced. Here we learned that the advancement of

engineering does not stop at the development of new technologies

and innovative functions; sometimes it is also for preventing from

deterioration. Only with the unceasing advancement of the

engineering technology can the construction masterpieces from many

years ago to be preserved to this day, and move on to the future

generations.

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5.3 Suicide

The purpose for building the Golden Gate Bridge was for

communicating the traffic on both sides; however; since the

completion of the bridge until this day, a problem has been bothering

the local authority - “suicides”. Each year, many people chose to

end their lives at the Golden Gate Bridge. Golden Gate Bridge has

become a popular site for suicide. According to the official

statistics, by 1993, over 1000 people committed suicide at the

Golden Gate Bridge. The Golden Gate Bridge Board of Directors

decided to invest 2 million US dollars to study the feasibility of

installing protective rails in preventing suicide attempts. Though

the number of suicides decreased, there still cannot prevent people

from leaping out of the Golden Gate Bridge to end their lives.

When Strauss was building this bridge, he highly valued the safety of

the workers during construction. In order to prevent the workers

from falling into the ocean, he even installed safety nets. This

showed that he respected human lives very much. Little did he

know that within 72 years of completion of this epic bridge, there

were over 1,300 lives that decided to end here.

Photo 17

Since completion, Golden Gate

Bridge has been the popular

suicide spot. Up till this day,

over 1300 people chose to end

their lives here.

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The latest statistic published by the Marin County

Coroner’s Office in California indicated that, there were

31 people ended their lives by jumping off the Golden

Gate Bridge, which was 3 lives less than the previous

year. Coroner Holmes said that there were 34 people

committed suicide by jumping off the bridge in 2008.

In the past 72 years, there were over 1,300 people

committed suicide there. The Golden Gate Bridge

District is seeking 50 million US dollar funding to install

stainless steel protective net underneath the

pedestrians walk on either side of the bridge to

intercept the jumpers. Relevant departments are still

making environmental assessment study for installing

the protective nets. Out of the 31 suicides, 20 bodies

were found by the US Coast Guard. 9 bodies were

either found in other counties or missing. Their

suicides were witnessed or caught on surveillance

cameras. Two suicides cases were found with suicide

notes. Holmes said that the statistic figure actually

was quite reserved, as many suicides did not leave any

trace behind which made it hard to calculate. There is

no knowing exactly how many committed suicide at the

bridge. Golden Gate Bridge is one of the most famous

suicide spots in the world. In the past 5 years, there

was average one person every two weeks that jumped

from the bridge. Four seconds after leaping off the 67

meters high bridge, the suicide will hit the ocean

surface at 120 miles per hour. Until 2003, there were

26 attempted suicides.

- Epochtimes, USA. http://www.dajiyuan.com

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Why would someone choose such a bridge to end his/her life?

The distance from the bridge to the ocean surface is about 60 meters,

there is great impact on the ocean surface after leaping off the bridge.

It is almost impossible to survive the strong current. Besides

Golden Gate Bridge, there are other famous suicide spots: Empire

State Building of New York City, Saint Peter’s Basilica (The Papal

Basilica of Saint Peter) in Vatican, Milan Cathedral (Duomo di

Milano), Mihara Volcanic Peak in Japan, and Eiffel Tower of Paris,

etc. Statistically speaking, however, Golden Gate Bridge remains

on the top of the suicides’ list. This fact makes one wonder, what is

the special meaning of committing suicide from the Golden Gate

Bridge? Why Golden Gate Bridge and not other places? There is

a Bay Bridge that is not far from the Golden Gate Bridge but the

number of jumpers were nowhere near the number as that of the

Golden Gate Bridge, why? Many experts who study suicides have

proposed their hypothesis. A column in the News of the World

wrote “Richard Seiden, the honorary professor to the School of

Public Health in UC Berkeley, has been studying suicides of the

Golden Gate Bridge for years. His research showed that many

suicides preferred to romanticize their death, thinking that leaping off

the Golden Gate Bridge to be something beautiful; whereas jumping

off the Bay Bridge was ‘lame’. Golden Gate Bridge is the world

first bridge across the ocean, crossing north and side sides of the San

Francisco Bay. The bridge is majestic and the view is spectacular.

When the dense fog blankets the bridge, only the top of the bridge

towers appear to be floating in mid air, and this makes people sigh

with owe, claiming it the ‘bridge in heaven’. 10 million tourists

visit here each year. Some claim that after a few minutes standing

on the bridge, they feel the urge to commit suicide. There is also an

urban legend saying that the Golden Gate Bridge ‘talks’, and it

whispers to urge you make the leap.”

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Whatever reasons people have in choosing the Golden Gate

Bridge as the terminal of their lives, the fundamental issue still lies in

the social care. Local newspaper once did a pole and found that

54% of the local San Francisco people were against installing safety

rails on the Golden Gate Bridge. They thought that even if the

suicides did not jump from the Golden Gate Bridge, they would still

find other places to do commit suicide. Installing the safety rails

perhaps would reduce the suicide rate, the rails would not help the

suicidal people get through the difficulties in life. Though no safety

rails were installed on the Golden Gate Bridge, there were

surveillance cameras and telephones for seeking assistance. This

could help those with suicide attempts or passer-bys to contact with

the Bridge control tower, notifying the management about the

possible suicide attempts and location. Here we learned that

obstacles reside not only in the process of construction. There are

other management, maintenance and safety issues after the

completion.

Photo 18. Dense fog makes people feel like being in heaven.

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Photo 19. Golden

Gate Bridge in the

dense fog is also

known as the

“Bridge in Heaven”.

The romantic

atmosphere may

well be the reason

why suicides choose

here to end their

lives.

Photo 20

Golden Gate Bridge

overcame many

challenges and

remained intact for

over 70 years since

completion. It’s

sturdiness and

beauty are deeply

recognized by

people.

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Char

t 1

Ch

alle

ng

es o

f S

an F

ranci

sco G

old

en G

ate

Bri

dge

Duri

ng a

nd A

fter

Const

ruct

ion

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6、 General Discussion

Building a ocean crossing large scale bridge may not be a

difficult task for the modern technology of today; however, before

the ages when the computers were not invented, to resist the

disadvantageous natural environment and at the same time fulfilling

the need of human being were huge construction challenges.

Golden Gate Bay is a place that is foggy, windy with strong currents

and constant earthquakes. Building a suspension bridge with

exceptionally long span to connect two places in order to promote

economy and transportation was not an easy job. Chief Engineer

Strauss himself was not an expert of suspension bridges; however,

through the unyielding effort of his persistence to the idea, and

assembling an elite team of different expertise, the Golden Gate

Bridge was finally completed in 1937. The case of Golden Gate

Bridge made us understand the importance of team work. Some

ideas may not be achieved by our own capability, it may well be

achieved by the support of teammates with abilities that we lack.

As new generation engineers, we should not be bound by our

insufficient professional ability and be afraid of taking the first step

towards our ideas. Many successful cases were realized gradually

with the courage in pursuing ideas and the attitude in humble

learning.

In addition to being human’s challenge against the nature,

Golden Gate Bridge also brings about the construction safety issues.

Under normal circumstances, construction work tends to focus on

user safety and reinforce the structural safety during the construction;

however, it tends to neglect the “builders’” safety. How to achieve

0 casualty during construction was one of the goals to which Strauss

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paid great respect; it should also be highly regarded by the future

construction process.

Photo 21. Teamwork and construction safety are what we should

learn from the Golden Gate Bridge.

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Practice

Part I : Use Your Brain

1. Do you think building an ocean crossing bridge on San Francisco

Bay was a good decision? Why? Would you be able to come

up with other transportation tools to promote the communication

and economic development of San Francisco County and Marin

County?

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2. If you were Strauss, what methods would you have adopted in

reducing the construction personnel casualty during the bridge

building process? (Use the natural environment of San Francisco

Bay for the overall consideration.)

第二部份 動動手

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3. Try think of some facilities that can be added to the San

Francisco Golden Gate Bridge to elevate the driving safety of

vehicles in the dense fog.

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4. If you were the designer of the Golden Gate Bridge, what color

would you have painted the bridge? Why? Elaborate your

ideas.

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5. San Francisco Golden Gate Bridge is a famous suicide spot.

Some people think that even if these people do not commit

suicide at the Golden Gate Bridge, they would still choose other

spots to end their lives. Do you agree with this? Think of

other ways to reduce the suicide rate of the Golden Gate Bridge.

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6. San Francisco Golden Gate Bridge must charge for the bridge

crossing to support the bridge maintenance expenses; however,

the income remains negative after all these years. Draft a

proposal to increase the Golden Gate Bridge operation income,

think of the negative effects that might come with the proposal,

and how to solve these negative effects.

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7. What are the issues to consider when designing a bridge that

connects to two places? Why?

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8. If you are the managing authority of the San Francisco Golden

Gate Bridge, and you receive a huge amount of subsidizing fund

for repairing the Golden Gate Bridge, what are the facilities you

want to add the most? Explain why.

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Part II : Use Your Hands

1. Elaborate your imagination and design a bridge to connect

Taiwan and Pen-Hu. What type of bridge you would design and

what are the facilities and function on the bridge? Draw

conceptual sketches.

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2. Find a bridge in life, take photos and paste the photos in the box

below. Try and analyze the advantages and disadvantages of the

bridge, and propose the improvement suggestion in the future.

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