Koyna Dam

Impounds Koyna River

LocaleKoyna Nagar, Maharashtra

 India

Length 807.2 m (2,648 ft)

Height 103.2 m (339 ft)

Opening date 1967

Dam owner(s) Government of Maharashtra

Reservoir information

Creates Shivaji Lake

Capacity2,797,400,000 m3 (9.8789×1010 cu ft)

Surface area 89,178 km2 (34,432 sq mi)

Power generation information

Turbines 18

Installed capacity 1,920 MW

Official website

The Koyna Dam is one of the largest dams in Maharashtra, India. It is located in Koyna Nagar, nestled in the Western Ghats on the state highway between Chiplun and Karad, Maharashtra.

The dam supplies water to western Maharashtra as well as cheap hydroelectric power to the neighbouring areas with a capacity of 1,920 MW. The Koyna project is actually composed of four dams, with the Koyna Dam having the largest catchment area.

The catchment area dams the Koyna River and forms the Shivaji Lake which is approximately 50 km (31 mi) in length. Completed in 1963, it is one of the largest civil engineering projects commissioned after Indian independence. The Koyna electricity project is run by the Maharashtra State Electricity Board. Most of the generators are located in excavated caves a kilometre deep, inside the heart of the surrounding hills.

The dam has contributed to earthquakes in the recent past, including the devastating 1967 Koynanagar earthquake that almost razed the dam, resulting in the dam developing major cracks.

Date

Built in: 1962 - 1963

Height of dam: 103 metres

Water storage: 2,797.400 km³

Volume of dam: 1,555.000 m³

Width of dam: 808 m

Slope at water side: 24:1

Length of lake: 60 km

• Storage:

o Gross storage: 98.78 TMC

o Live: 93.65 TMC

o Dead: 5.125 TMC

• Length: 1807.22 m

• Height: 85.35 m

• Year of completion: 1963

Jayakwadi DamFrom Wikipedia, the free encyclopedia

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Jayakwadi Dam

Jayakwadi Dam on Godavari River.

Jayakwadi project is one of the largest irrigation projects in Maharashtra. It is a multipurpose project. Its water is used mainly to irrigate agricultural land in the drought prone Marathwada region of Maharashtra state. It also provides water for drinking and industrial usage to nearby towns and villages and to the municipalities and industrial areas of Aurangabad and Jalna. The surrounding area of the dam has a beautiful garden and a bird sanctuary.

Location

It is located on Godavari river at the site of Jayakwadi village in Paithan taluka of Aurangabad district in Maharashtra state, India.

Foundation

Foundation was laid by late Prime minister Lal Bahadur Shastri on 18 October 1965.

Inauguration

Inaugurated by late Prime minister Indira Gandhi on 24 February 1976.

Purpose

Multipurpose project. Mainly To irrigate land for agriculture in the drought prone of Marathwada region of Maharashtra state. Also to provide water for drinking and industrial usage to nearby towns and villages and to the municipalities and industrial areas of Aurangabad and Jalna.

Statistics

Built in: 1965–1976

Height of dam:

40 m approx

Water storage: 2.909 km3

Width of dam:9998 m (10 km approx)

Area of Reservoir :

350 km2

About the dam

Jayakwadi project is one of the largest irrigation projects in Aurangabad Maharashtra. o It is a multipurpose project.o Jayakwadi is one of the largest earthen dams in Asia.o Its cachement area is 21,750 km².o Total submergence area due to the reservoir is approx 35,000 ha.o Its height is approx 41.30 m and length of 9998 m (10 km approx)o Nath Sagar is the name of the reservoir formed due to Jayakwadi Dam.o Total area of reservoir is approx 350 km2.o Its total storage capicity is approx 2.909 km³ & effective live storage capacity is

2.17 km³.o The length of left bank canal is 208 km & the length of right bank canal is

132 km.

o It irrigates culturable area of 237,452 ha in the districts of Aurangabad, Jalna,

Beed and Parbhani. While its total command area is 263,858 ha.o Its installed power generating capacity is 12 megawatts.o It is also used to supply drinking water to Aurangabad city & surrounding areas.o Unfortunately siltation has taken a heavy toll on the project. It is estimated that

appprox 30% of the dam is filled with silt, reducing its life as well as storage capacity.

In the year 2009 it has entered in 35th year of its life. It has in its lifetime overflowed only 17 times. On 10 August 2006 highest discharge of 250000 ft³/s was recorded.

Migratory birds at Jayakwadi Dam, Aurangabad

Dnyneshwar Udyan

Dnyaneshwar Udyan is one of the largest gardens in Maharashtra resembling the Vrindavan Gardens of Mysore. It is spread over 125 hectares and is situated on the banks of Nathsagar Lake formed due to Jayakwadi Dam. It is located near the town of Paithan which is 40 km south of Aurangabad and nearly about 22 km east to hatgaon which is femous in all over india

Itaipu Dam

Official name

Central Hidroeléctrica Itaipú

Binacional

Usina Hidrelétrica Itaipu Binacional

Impounds Paraná River

LocaleFoz do Iguaçu

Ciudad del Este

Length 7,700 m (25,300 ft)

Height 196 m (643 ft)

Hydraulic head 118 m (387 ft)

Construction began January 1970

Opening date 5 May 1984

Construction cost US$19.6 billion

Maintained by Itaipu Binacional

Reservoir information

Creates Itaipu Reservoir

Capacity 29,000,000,000 m3 (1.0×1012 cu ft)

Catchment area 1,350 km2 (520 sq mi)

Power generation information

Turbines 20 × 700 MW

Installed capacity 14,000 MW

Annual generation 91.6 TWh (2009)

Conventional Yes

Websitewww.itaipu.gov.br

www.itaipu.gov.py

The Itaipu Dam (Guarani: Itaipu, Portuguese: Itaipu, Spanish: Itaipú; Portuguese

pronunciation: Spanish pronunciation: is a hydroelectric dam on the Paraná River located on the

border between Brazil and Paraguay. The name "Itaipu" was taken from an isle that existed near

the construction site. In the Guarani language, Itaipu means "the sound of a stone". The

American composer Philip Glass has also written a symphonic cantata named Itaipu, in honour

of the structure.

The dam is the largest operating hydroelectric facility in terms of annual generating capacity,

generating 94.7 TWh in 2008 and 91.6 TWh in 2009, while the annual generating capacity of the

Three Gorges Dam was 80.8 TWh in 2008 and 79.4 TWh in 2009.[1] It is a binational undertaking

run by Brazil and Paraguay at the Paraná River on the border section between the two countries,

15 km (9.3 mi) north of the Friendship Bridge. The project ranges from Foz do Iguaçu, in Brazil,

and Ciudad del Este in Paraguay, in the south to Guaíra and Salto del Guaíra in the north. The

installed generation capacity of the plant is 14 GW, with 20 generating units providing 700 MW

each with a hydraulic design head of 118 m. In 2008 the plant generated a record 94.68 billion

kWh, supplying 90% of the energy consumed by Paraguay and 19% of that consumed by Brazil.[2]

Of the twenty generator units currently installed, ten generate at 50 Hz for Paraguay and ten

generate at 60 Hz for Brazil. Two 600 kV HVDC lines, each approximately 800 km long, carry

both Brazilian and Paraguayan energy to São Paulo where the terminal equipment converts the

power to 60 Hz.

History

Negotiations between Brazil and Paraguay

The concept behind Itaipu Power Plant was the result of heavy negotiations between the two

countries during the 1960s. The "Ata do Iguaçu" (Iguaçu Act) was signed on July 22, 1966, by

the Brazilian and Paraguayan Ministers of Foreign Affairs, Juracy Magalhães and Sapena Pastor,

respectively. This was a joint declaration of the mutual interest in studying the exploitation of the

hydric resources that the two countries shared in the section of the Paraná River starting from,

and including, the Salto de Sete Quedas, to the Iguaçu River's watershed. The Treaty that gave

origin to the power plant was signed in 1973.

The terms of the treaty, which expires in 2023, have been the subject of widespread discontent in

Paraguay. The government of President Lugo vowed to renegotiate the terms of the treaty with

Brazil, which long remained hostile to any renegotiation.[3]

In 2009, Brazil agreed to a fairer payment of electricity to Paraguay and also allowed Paraguay

to sell excess power directly to Brazilian companies instead of solely through the Brazilian

electricity monopoly.[4][5]

Construction starts

The dam undergoes expansion work.

In 1970, the consortium formed by the companies IECO (from the United States of America) and

ELC Electroconsult S.p.A. (from Italy) won the international competition for the realization of

the viability studies and for the elaboration of the construction project. Work began in February

1971. On April 26, 1973, Brazil and Paraguay signed the Itaipu Treaty, the legal instrument for

the hydroelectric exploitation of the Paraná River by the two countries. On May 17, 1974, the

Itaipu Binacional entity was created to administer the plant's construction. The works began in

January of the following year.

Paraná River rerouted

On October 14, 1978, the Paraná River had its route changed, which allowed a section of the

riverbed to dry so the dam could be built there.

Agreement by Brazil, Paraguay, and Argentina

An important diplomatic settlement was reached with the signing of the Acordo Tripartite by

Brazil, Paraguay and Argentina, on October 19, 1979. This agreement established the allowed

river levels and how much they could change as a result of the various hydroelectrical

undertakings in the watershed that was shared by the three countries. At that time, the three

countries were ruled by military dictatorships. Argentina was concerned that, in the event of a

conflict, Brazil could open the floodgates, raising the water level in the River Plate and

consequently flood the capital city of Buenos Aires.

Formation of the lake

The plant's reservoir began its formation on October 13, 1982, when the dam works were

completed and the side canal's gates were closed. Throughout this period, heavy rains and

flooding accelerated the filling of the reservoir as the water rose 100 meters (330 ft) and reached

the gates of the spillway at 10 a.m. on October 27.

Start of operations

On May 5, 1984, the first generation unit started running in Itaipu. The first 18 units were

installed at the rate of two to three a year; the last two of these started running in the year 1991.

Capacity expansion in 2007

The last two of the 20 electric generation units started operations in September 2006 and in

March 2007, thus raising the installed capacity to 14 GW and completing the power plant. This

increase in capacity will allow for 18 generation units to remain running all of the time while two

stay down for maintenance. Due to a clause in the treaty signed between Brazil, Paraguay and

Argentina, the maximum number of generating units allowed to operate simultaneously cannot

exceed 18 (see the agreement section for more information).

The rated nominal power of each generating unit (turbine and generator) is 700 MW. However,

because the head (difference between reservoir level and the river level at the foot of the dam)

that actually occurs is higher than the designed head (118 m), the power available exceeds 750

MW half of the time for each generator.

Each turbine generates around 700 MW; by comparison, all the water from the Iguaçu Falls

would have the capacity to feed only two generators.

November 2009 power failure

On November 10, 2009, transmission from the plant was totally disrupted, possibly due to a

storm damaging up to three high-voltage distribution lines.[6] Itaipu itself was not damaged. This

caused massive power outages in Brazil and Paraguay, blacking out the entire country of

Paraguay for 15 minutes, and plunging Rio de Janeiro and São Paulo into darkness for more than

2 hours. 50 million people were reportedly affected.[7] The blackout hit at 10:13 p.m. local time.

It affected the southeast of Brazil most severely, leaving São Paulo, Rio de Janeiro and Espírito

Santo completely without electricity. Blackouts also swept through the interior of Rio Grande do

Sul, Santa Catarina, Mato Grosso do Sul, Mato Grosso, the interior of Bahia and parts of

Pernambuco, energy officials said.[8] By 12:30 a.m. power had been restored to most areas.

Wonder of the Modern World

In 1994, the American Society of Civil Engineers elected the Itaipu Dam as one of the seven

modern Wonders of the World. In 1995, the American magazine Popular Mechanics published

the results.[9]

Social and environmental impacts

When construction of the dam began, approximately 10,000 families living beside the Paraná

River were displaced.[10]

The world's largest waterfall by volume, the Guaíra Falls were drowned by the newly formed

Itaipu reservoir. The Brazilian government liquidated the Guaíra Falls National Park, and

dynamited the submerged rock face where the falls had been, facilitating safer navigation, but

eliminating the possibility of restoring the falls in the future. A few months before the reservoir

was filled, 80 people died when an overcrowded bridge overlooking the falls collapsed, as

tourists sought a last glimpse of the falls.[11]

Statistics

Spillways in action.

Construction

The course of the seventh biggest river in the world was shifted, as were 50 million tons

of earth and rock.

The amount of concrete used to build the Itaipu Power Plant would be enough to build

210 football stadiums the size of the Estádio do Maracanã.

The iron and steel used would allow for the construction of 380 Eiffel Towers.

The volume of excavation of earth and rock in Itaipu is 8.5 times greater than that of the

Channel Tunnel and the volume of concrete is 15 times greater.

Around forty thousand people worked in the construction.[citation needed]

The cost of constructing Itaipu makes it one of the most expensive objects ever built.

Generating station and dam

The total length of the dam is 7235 m. The crest elevation is 225 m. Itaipu is actually four

dams joined together — from the far left, an earth fill dam, a rock fill dam, a concrete

main dam, and a concrete wing dam to the right.

The spillway has a length of 483 m.

The maximum flow of Itaipu's fourteen segmented spillways is 62.2 thousand cubic

metres per second, into three skislope formed canals. It is equivalent to 40 times the

average flow of the nearby natural Iguaçu Falls.

The flow of two generators (700 m3·s−1 each) is roughly equivalent to the average flow of

the Iguaçu Falls (1500 m3·s−1).

If Brazil were to use Thermal Power Generation to produce the electric power of Itaipu,

434,000 barrels (69,000 m3) of petroleum would have to be burned every day.

The dam is 196 metres high, equivalent to a 65-story building.[12]

Though it is the seventh largest reservoir in size in Brazil, the Itaipu's reservoir has the

best relation between electricity production and flooded area. For the 14,000 MW

installed power, 1350 square kilometres were flooded. The reservoirs for the

hydroelectric power plants of Sobradinho Dam, Tucuruí Dam, Porto Primavera Dam,

Balbina Dam, Serra da Mesa Dam and Furnas Dam are all larger than the one for Itaipu,

but have a smaller installed generating capacity. The one with the largest hydroelectric

production, Tucuruí, has an installed capacity of 8,000 MW, while flooding 2,430 km2

(938 sq mi) of land.

Hoover Dam, Facts, Statistics and Project Construction

Hoover Dam

Hoover dam is America's most famous landmark, completed in 1935. It was the most colossal

structure in the world at that time. This great American icon was to be the largest and heaviest

dam, producing the largest amount of Hydro electric power in the world.

The Hoover sketch details

21000 men took part in its construction and of them 112 laid their lives to complete this

megastructure. Though its not the superior dam today but still most famous, iconic and greatest

dam ever built. Situated in Mojave desert, 30 Km south-east of Las Vegas. Built on Colorado

River at Black Canyon, the construction site was extremely difficult. The risks involved were

huge and the consequences could have been catastrophic, if the dam failed.

Hoover Dam is 221m high, 201 meters thick and 3.4 million cubic meters of concrete has been

used in it.

Background for Hoover Construction

Colorado, worlds one of the most powerful and unpredictable rivers, would break its banks in

every spring and flood the area. The Government instructed the Bureau of Reclamation to come

up with a solution and they decided to build world's largest dam. The site chosen for the

megastructure Hoover Dam was Black Canyon. It is an 800 ft high deep gorge through which the

river flowed. The spot, Black canyon is in the middle of the desert, so there was no

infrastructure, no labors, no transportation and the weather too was harsh.

Frank Crow, was the Chief Engineer of Hoover Dam and was assigned the job to get it

completed in the span from 1931 – 1935. The construction of Hoover took 7 years at a cost of $

125 million. Nowadays this amount is about 788 million pounds. If the dam was not completed

in the given time it would have cost the contractors $ 3000 / day in financial penalties.

Stage 1 of construction

Hoover Tunnels

Hoover Tunnels. Tunnels Used to divert water from dam site

In April 1931 blasting for construction of plain dry area, upon which dam would be built, began.

To divert the Colorado river 4 tunnels were to be excavated on each side of the Canyon,

measuring 4000 ft long and the diameter of the tunnel was 56 ft, these were acting as diversion

channels. Two tunnels would be constructed on the Nevada side, and another two were to be

constructed on the Arizona side. 2 small cofferdams were built to force water into the tunnels. In

may 1931 the drilling continued. The digging, blasting, and debris removal continued for 13

months, with men working 3 shifts 24 hours a day, 7 days a week. Holidays were observed only

at Christmas, 4rth July and Labor Day. The workers had to face harsh conditions but were paid

only 40% extra. No proper ventilation was provides, work was extremely physically demanding.

Men had to swing 100's of feet down the canyon walls to remove dangerous loose rocks, using

jacks and dynamites. Due to lack of safety measure men required nerves of steel. The most

common cause of death was, being hit by falling rocks.

Coffer dams, to build Hoover Dam

Because no roads led into the canyon, men (as well as equipment) arrived at the work site by

boat. Workers used 500 pneumatic drills, hoses, and compressors to make holes in the canyon

rock where explosives could be placed. Once holes were drilled, workers used dynamite to blast

into the rock and break it into smaller pieces that could be hauled away by dump trucks. A ton

(0.9 metric tons) of dynamite was required for every 14 feet (4.3 meters) of tunnel that workers

dug into the canyon wall. Special team then visited the inside of the tunnels to ensure it would

remain same for workers to work inside it. The tunnels were then lined with concrete and By

sliding sticks of dynamite into holes bored into the canyon wall, workers were able to blast and

excavate large diversion tunnels. These tunnels, each about the size of a 4-lane highway, were

lined with 3 feet of concrete, allowing river water to be transported away from the

construction site at a rate of 1.5 million gallons per second.

Till November, 14, 1932 four 4 tunnels were completed and the water was allowed to flow

through it.

Coffer Dams

Workers made the cofferdams by using 100 trucks to dump dirt, rock, and debris into the water

at a rate of one truckload every 15 seconds. This amazing pace of dredging and dumping went on

for five months. The largest flow ever recorded at Black Canyon 200,000 cubic feet per second,

was used by the Engineers to design the coffer dams.

Stage 2 of construction

In this stage building the dam itself was the task. The work was too huge, there were many

problems in design which needed to be solved.

Design of the Hoover Dam

Hoover is a Gravity dam, stabilized by its huge mass

Hoover is an arch gravity dam, incorporating two principles.

According to the first principle, the weight of the dam forces it into the ground due to its weight,

thus helping it to remain stable.

In another principle, the arch shape of the dam deflects the force of the water into the canyon

walls through the compression of dam's concrete walls, using the compressive strength of

concrete (concrete is very strong in compression).

 

Major problem was the pouring of 3.4 million cubic meters of concrete. Plants were installed at

the construction site to produce concrete locally. But the dam was too big to be made into a

single concrete mount. If the concrete in the dam was poured in only one go, the concrete would

not have settled even today.

It is because when ingredients of concrete – cement, sand, coarse aggregate combine in the

presence of water, they start a chemical reaction, resulting in the generation of internal heat, thus

slowing down the curing process. The large the pour, the larger the cure. If heat is not dispersed,

cracks would form, weakening the structure.

Heat of hydration in Hoover dam

The cooling of Blocks to avoid shrinkage due to heat evolution

To counteract the problem of heat generation, Hoover dam was built in series of inter locking

blocks. This idea was conceived by a previous dam called Lower Crystal Spring dams. But

Hoover was even 20 times massive than gigantic Lower Crystals Spring Dam. Each block was 5

ft high and was inter locked with the neighboring one and water was forced between them. To

accelerate the setting of concrete, cool water pipes were passed through each block. Concrete

mix was cooled and cured faster. To speed up pouring of concrete in the mega structure, an

elaborate overhead network of cables and pulleys was designed, carrying vast buckets of

concrete. Labors stayed on the site to spread, place and compact the poured in concrete. Due to

this new method, a record breaking volume – 8000 cubic meters of concrete was poured in a

single day.

Akashi Kaikyō Bridge

Akashi Kaikyō Bridge

Akashi Kaikyō Ō-hashi (明石海峡大橋?)

Akashi Kaikyō Bridge from the air.

Other name(s) Pearl bridge

Carries 6 lanes of roadway

Crosses Akashi Strait[1]

Locale Awaji Island and Kobe[1]

Maintained by Honshū-Shikoku Bridge Authority

Design Suspension bridge[1]

Total length 3,911 meters (12,831 ft)

Height 282.8 metres (928 ft) (pylons)[1]

Longest span 1,991 meters (6,532 ft)[1]

Clearance

below65.72 meters

Beginning date

of construction1988[1]

Completion

date1998[1]

Opened April 5, 1998

Toll ¥2,300

Coordinates

34°36′59″N 135°01′13″E /

34.61639°N

135.02028°E Coordinates:

34°36′59″N 135°01′13″E /

34.61639°N 135.02028°E

The Akashi-Kaikyō Bridge also known as the Pearl Bridge, has the longest central span of any

suspension bridge, at 1,991 metres (6,532 ft). It is located in Japan and was completed in 1998[1].

The bridge links the city of Kobe on the mainland of Honshū to Iwaya on Awaji Island by

crossing the busy Akashi Strait. It carries part of the Honshū-Shikoku Highway.

The bridge is one of the key links of the Honshū-Shikoku Bridge Project, which created three

routes across the Inland Sea.

History

Before the Akashi Kaikyō Bridge was built, ferries carried passengers across the Akashi Strait in

Japan. This dangerous waterway often experiences severe storms, and in 1955, two ferries sank

in the strait during a storm, killing 168 children. The ensuing shock and public outrage

convinced the Japanese government to develop plans for a suspension bridge to cross the strait.

The original plan called for a mixed railway-road bridge, but when construction on the bridge

began in April 1986, the construction was restricted to road only, with six lanes. Actual

construction did not begin until May 1986, and the bridge was opened for traffic on April 5,

1998. The Akashi Strait is an international waterway that necessitated the provision of a 1,500-

metre (4,921 ft)-wide shipping lane.

Architecture

The bridge has three spans. The central span is 1,991 m (6,532 ft)[1], and the two other sections

are each 960 m (3,150 ft). The bridge is 3,911 m (12,831 ft) long overall. The central span was

originally only 1,990 m (6,529 ft), but the Kobe earthquake on January 17, 1995, moved the two

towers sufficiently (only the towers had been erected at the time) so that it had to be increased by

1 m (3.3 ft).[1]

The bridge was designed with a two-hinged stiffening girder system, allowing the structure to

withstand winds of 286 kilometres per hour (178 mph), earthquakes measuring to 8.5 on the

Richter scale, and harsh sea currents. The bridge also contains pendulums that are designed to

operate at the resonance frequency of the bridge to damp forces. The two main supporting towers

rise 298 m (978 ft) above sea level, and the bridge can expand because of heating up to 2 metres

(7 ft) over the course of a day. Each anchorage required 350,000 tonnes (340,000 LT; 390,000

ST) of concrete. The steel cables have 300,000 kilometres (190,000 mi) of wire: each cable is

112 centimetres (44 in) in diameter and contains 36,830 strands of wire.[2][3]

The Akashi-Kaikyo bridge has a total of 1737 illumination lights: 1084 for the main cables, 116

for the main towers, 405 for the girders and 132 for the anchorages. On the main cables three

high light discharged tubes are mounted in the colors red, green and blue. The RGB model and

computer technology make for a variety of combinations. Currently, 28 patterns are used for

occasions as national or regional holidays, memorial days or festivities.[citation needed]

Use

The total cost is estimated at ¥500 billion, and is expected to be defrayed by charging commuters

a toll to cross the bridge. The toll is ¥2,300 and the bridge is used by approximately 23,000

cars/day.[4]

Nearby attractions

Two parks in proximity of the bridge have been built for tourists, one in Maiko (including a

small museum) and one in Asagiri. Both are accessible by the coastal train line.

Golden Gate Bridge

Golden Gate Bridge

Carries6 lanes of US 101 / SR 1 ,

pedestrians and bicycles

Crosses Golden Gate

LocaleSan Francisco, California and Marin

County, California

Maintained byGolden Gate Bridge, Highway and

Transportation District[1]

DesignerJoseph Strauss, Irving Morrow, and

Charles Ellis

DesignSuspension, truss arch & truss

causeways

Total length1.7 mi (2.7 km) or 8,981 ft (2,737.4

m)[2]

Width 90 ft (27.4 m)

Height 746 ft (227.4 m)

Longest span 4,200 ft (1,280.2 m)[3]

Vertical

clearance

14 ft (4.3 m) at toll gates, higher

truck loads possible

Clearance

below220 ft (67.1 m) at mean high water

Opened May 27, 1937

Toll Cars (southbound only)

$6.00 (cash), $5.00 (FasTrak), $3.00

(carpools during peak hours, FasTrak

only)

Daily traffic 118,000[4]

Connects:

San Francisco

Peninsula with

Marin County

Coordinates

37°49′11″N 122°28′43″W /

37.81972°N

122.47861°W Coordinates:

37°49′11″N 122°28′43″W /

37.81972°N 122.47861°W

The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the opening of the

San Francisco Bay into the Pacific Ocean. As part of both U.S. Route 101 and California State

Route 1, it connects the city of San Francisco on the northern tip of the San Francisco Peninsula

to Marin County. The Golden Gate Bridge was the longest suspension bridge span in the world

when it was completed during the year 1937, and has become one of the most internationally

recognized symbols of San Francisco, California, and of the United States. Despite its span

length being surpassed by eight other bridges since its completion, it still has the second longest

suspension bridge main span in the United States, after the Verrazano-Narrows Bridge in New

York City. It has been declared one of the modern Wonders of the World by the American

Society of Civil Engineers. The Frommers travel guide considers the Golden Gate Bridge the

"possibly the most beautiful, certainly the most photographed, bridge in the world" [5] (although

Frommers also bestows the most photographed honor on Tower Bridge in London, England).[6]

History

Golden Gate with Fort Point in foreground, circa 1891

Before the bridge was built, the only practical short route between San Francisco and what is

now Marin County was by boat across a section of San Francisco Bay. Ferry service began as

early as 1820, with regularly scheduled service beginning in the 1840s for purposes of

transporting water to San Francisco.[7] The Sausalito Land and Ferry Company service, launched

in 1867, eventually became the Golden Gate Ferry Company, a Southern Pacific Railroad

subsidiary, the largest ferry operation in the world by the late 1920s.[7][8] Once for railroad

passengers and customers only, Southern Pacific's automobile ferries became very profitable and

important to the regional economy.[9] The ferry crossing between the Hyde Street Pier in San

Francisco and Sausalito in Marin County took approximately 20 minutes and cost US$1.00 per

vehicle, a price later reduced to compete with the new bridge. [10] The trip from the San Francisco

Ferry Building took 27 minutes.

Many wanted to build a bridge to connect San Francisco to Marin County. San Francisco was the

largest American city still served primarily by ferry boats. Because it did not have a permanent

link with communities around the bay, the city's growth rate was below the national average. [11]

Many experts said that a bridge couldn’t be built across the 6,700 ft (2,042 m) strait. It had

strong, swirling tides and currents, with water 500 ft (150 m) in depth at the center of the

channel, and frequent strong winds. Experts said that ferocious winds and blinding fogs would

prevent construction and operation.[11]

Conception

Although the idea of a bridge spanning the Golden Gate was not new, the proposal that

eventually took place was made in a 1916 San Francisco Bulletin article by former engineering

student James Wilkins.[12] San Francisco's City Engineer estimated the cost at $100 million,

impractical for the time, and fielded the question to bridge engineers of whether it could be built

for less.[7] One who responded, Joseph Strauss, was an ambitious but dreamy engineer and poet

who had, for his graduate thesis, designed a 55-mile (89 km) long railroad bridge across the

Bering Strait.[13] At the time, Strauss had completed some 400 drawbridges—most of which were

inland—and nothing on the scale of the new project.[3] Strauss's initial drawings[12] were for a

massive cantilever on each side of the strait, connected by a central suspension segment, which

Strauss promised could be built for $17 million.[7]

Local authorities agreed to proceed only on the assurance that Strauss alter the design and accept

input from several consulting project experts.[citation needed] A suspension-bridge design was

considered the most practical, because of recent advances in metallurgy.[7]

Strauss spent more than a decade drumming up support in Northern California. [14] The bridge

faced opposition, including litigation, from many sources. The Department of War was

concerned that the bridge would interfere with ship traffic; the navy feared that a ship collision or

sabotage to the bridge could block the entrance to one of its main harbors. Unions demanded

guarantees that local workers would be favored for construction jobs. Southern Pacific Railroad,

one of the most powerful business interests in California, opposed the bridge as competition to

its ferry fleet and filed a lawsuit against the project, leading to a mass boycott of the ferry

service.[7] In May 1924, Colonel Herbert Deakyne held the second hearing on the Bridge on

behalf of the Secretary of War in a request to use Federal land for construction. Deakyne, on

behalf of the Secretary of War, approved the transfer of land needed for the bridge structure and

leading roads to the "Bridging the Golden Gate Association" and both San Francisco County and

Marin County, pending further bridge plans by Strauss.[15] Another ally was the fledgling

automobile industry, which supported the development of roads and bridges to increase demand

for automobiles.[10]

The bridge's name was first used when the project was initially discussed in 1917 by M.M.

O'Shaughnessy, city engineer of San Francisco, and Strauss. The name became official with the

passage of the Golden Gate Bridge and Highway District Act by the state legislature in 1923.[16]

Design

South tower seen from walkway

Strauss was chief engineer in charge of overall design and construction of the bridge project. [11]

However, because he had little understanding or experience with cable-suspension designs,[17]

responsibility for much of the engineering and architecture fell on other experts.

Irving Morrow, a relatively unknown residential architect, designed the overall shape of the

bridge towers, the lighting scheme, and Art Deco elements such as the streetlights, railing, and

walkways. The famous International Orange color was originally used as a sealant for the bridge.

Many locals persuaded Morrow to paint the bridge in the vibrant orange color instead of the

standard silver or gray, and the color has been kept ever since.[18]

Senior engineer Charles Alton Ellis, collaborating remotely with famed bridge designer Leon

Moisseiff, was the principal engineer of the project.[19] Moisseiff produced the basic structural

design, introducing his "deflection theory" by which a thin, flexible roadway would flex in the

wind, greatly reducing stress by transmitting forces via suspension cables to the bridge towers. [19]

Although the Golden Gate Bridge design has proved sound, a later Moisseiff design, the original

Tacoma Narrows Bridge, collapsed in a strong windstorm soon after it was completed, because

of an unexpected aeroelastic flutter.[20]

Ellis was a Greek scholar and mathematician who at one time was a University of Illinois

professor of engineering despite having no engineering degree (he eventually earned a degree in

civil engineering from University of Illinois prior to designing the Golden Gate Bridge and spent

the last twelve years of his career as a professor at Purdue University). He became an expert in

structural design, writing the standard textbook of the time.[21] Ellis did much of the technical and

theoretical work that built the bridge, but he received none of the credit in his lifetime. In

November 1931, Strauss fired Ellis and replaced him with a former subordinate, Clifford Paine,

ostensibly for wasting too much money sending telegrams back and forth to Moisseiff. [21] Ellis,

obsessed with the project and unable to find work elsewhere during the Depression, continued

working 70 hours per week on an unpaid basis, eventually turning in ten volumes of hand

calculations.[21]

With an eye toward self-promotion and posterity, Strauss downplayed the contributions of his

collaborators who, despite receiving little recognition or compensation,[17] are largely responsible

for the final form of the bridge. He succeeded in having himself credited as the person most

responsible for the design and vision of the bridge.[21] Only much later were the contributions of

the others on the design team properly appreciated.[21] In May 2007, the Golden Gate Bridge

District issued a formal report on 70 years of stewardship of the famous bridge and decided to

give Ellis major credit for the design of the bridge.

Finance

The Golden Gate Bridge and Highway District, authorized by an act of the California

Legislature, was incorporated in 1928 as the official entity to design, construct, and finance the

Golden Gate Bridge.[11] However, after the Wall Street Crash of 1929, the District was unable to

raise the construction funds, so it lobbied for a $30 million bond measure. The bonds were

approved in November 1930,[13] by votes in the counties affected by the bridge.[22] The

construction budget at the time of approval was $27 million. However, the District was unable to

sell the bonds until 1932, when Amadeo Giannini, the founder of San Francisco–based Bank of

America, agreed on behalf of his bank to buy the entire issue in order to help the local economy.[7]

Construction

Construction began on January 5, 1933.[7] The project cost more than $35 million.[23]

Strauss remained head of the project, overseeing day-to-day construction and making some

groundbreaking contributions. A graduate of the University of Cincinnati, he placed a brick from

his alma mater's demolished McMicken Hall in the south anchorage before the concrete was

poured. He innovated the use of movable safety netting beneath the construction site, which

saved the lives of many otherwise-unprotected steelworkers. Of eleven men killed from falls

during construction, ten were killed (when the bridge was near completion) when the net failed

under the stress of a scaffold that had fallen.[24] Nineteen others who were saved by the net over

the course of construction became proud members of the (informal) Halfway to Hell Club.[25]

The project was finished by April 1937, $1.3 million under budget.[7]

Opening festivities

Opening of the Golden Gate Bridge

The bridge-opening celebration began on May 27, 1937 and lasted for one week. The day before

vehicle traffic was allowed, 200,000 people crossed by foot and roller skate. [7] On opening day,

Mayor Angelo Rossi and other officials rode the ferry to Marin, then crossed the bridge in a

motorcade past three ceremonial "barriers", the last a blockade of beauty queens who required

Joseph Strauss to present the bridge to the Highway District before allowing him to pass. An

official song, "There's a Silver Moon on the Golden Gate", was chosen to commemorate the

event. Strauss wrote a poem that is now on the Golden Gate Bridge entitled "The Mighty Task is

Done." The next day, President Roosevelt pushed a button in Washington, D.C. signaling the

official start of vehicle traffic over the Bridge at noon. When the celebration got out of hand, the

SFPD had a small riot in the uptown Polk Gulch area. Weeks of civil and cultural activities

called "the Fiesta" followed. A statue of Strauss was moved in 1955 to a site near the bridge.[12]

Description

Specifications

A photograph of the bridge from a boat

Fog at the Golden Gate Bridge, San Francisco

The center span was the longest among suspension bridges until 1964 when the Verrazano-

Narrows Bridge was erected between the boroughs of Staten Island and Brooklyn in New York

City, surpassing the Golden Gate Bridge by 60 feet (18 m).The Golden Gate Bridge also had the

world's tallest suspension towers at the time of construction and retained that record until more

recently. In 1957, Michigan's Mackinac Bridge surpassed the Golden Gate Bridge's total length

to become the world's longest two-tower suspension bridge in total length between anchorages,

but the Mackinac Bridge has a shorter suspended span (between towers) compared to the Golden

Gate Bridge.

Structure

The weight of the roadway is hung from two cables that pass through the two main towers and

are fixed in concrete at each end. Each cable is made of 27,572 strands of wire. There are 80,000

miles (129,000 km) of wire in the main cables.[26] The bridge has approximately 1,200,000 total

rivets.

Traffic

As the only road to exit San Francisco to the north, the bridge is part of both U.S. Route 101 and

California Route 1. The median markers between the lanes are moved to conform to traffic

patterns. On weekday mornings, traffic flows mostly southbound into the city, so four of the six

lanes run southbound. Conversely, on weekday afternoons, four lanes run northbound. Although

there has been discussion concerning the installation of a movable barrier since the 1980s, the

Bridge Board of Directors, in March 2005, committed to finding funding to complete the $2

million study required prior to the installation of a movable median barrier. The eastern walkway

is for pedestrians and bicycles during the weekdays and during daylight hours only (6:30 am to

3:30 pm), and the western walkway is open to bicyclists on weekday afternoons (after 3:30 pm),

weekends, and holidays (3:30 pm to 6:30 am).

The speed limit on the Golden Gate Bridge was reduced from 55 mph (89 km/h) to 45 mph (72

km/h) on 1 October 1996.

Aesthetics

The Golden Gate Bridge by night, with part of downtown San Francisco visible in the

background at far left

Despite its red appearance, the color of the bridge is officially an orange vermillion called

international orange.[27] The color was selected by consulting architect Irving Morrow because it

complements the natural surroundings and enhances the bridge's visibility in fog. Aesthetics was

the foremost reason why the first design of Joseph Strauss was rejected. Upon re-submission of

his bridge construction plan, he added details, such as lighting, to outline the bridge's cables and

towers.[28] In 1999, it was ranked fifth on the List of America's Favorite Architecture by the

American Institute of Architects.

Paintwork

The bridge was originally painted with red lead primer and a lead-based topcoat, which was

touched up as required. In the mid-1960s, a program was started to improve corrosion protection

by stripping the original paint and repainting the bridge with zinc silicate primer and vinyl

topcoats.[29][30] Since 1990 Acrylic topcoats have been used instead for air-quality reasons. The

program was completed in 1995 and it is now maintained by 38 painters who touch up the

paintwork where it becomes seriously eroded.[31]

Current issues

Economics

The last of the construction bonds were retired in 1971, with $35 million in principal and nearly

$39 million in interest raised entirely from bridge tolls.[32]

In November 2006, the Golden Gate Bridge, Highway and Transportation District recommended

a corporate sponsorship program for the bridge to address its operating deficit, projected at $80

million over five years. The District promised that the proposal, which it called a "partnership

program", would not include changing the name of the bridge or placing advertising on the

bridge itself. In October 2007, the Board unanimously voted to discontinue the proposal and seek

additional revenue through other means, most likely a toll increase.[33][34]

On 2 September 2008, the auto cash toll for all southbound motor vehicles was raised from $5 to

$6, and the FasTrak toll was increased from $4 to $5. Bicycle, pedestrian, and northbound motor

vehicle traffic remain toll free.[35] For vehicles with more than two axles, the toll rate is $2.50 per

axle.[36][37]

Congestion pricing

Further information: San Francisco congestion pricing

In March 2008, the Golden Gate Bridge District board approved a resolution to implement

congestion pricing at the Golden Gate Bridge, charging higher tolls during peak hours, but rising

and falling depending on traffic levels. This decision allowed the Bay Area to meet the federal

requirement to receive $158 million in federal transportation funds from USDOT Urban

Partnership grant.[38] As a condition of the grant, the congestion toll must be in place by

September 2009.[39][40]

The first results of the study, called the Mobility, Access and Pricing Study (MAPS), showed

that a congestion pricing program is feasible.[41] The different pricing scenarios considered were

presented in public meetings in December 2008 and the final study results are expected for late

2009.[42]

Suicides

As a suicide prevention initiative, this sign promotes a special telephone available on the bridge

that connects to a crisis hotline.

The Golden Gate Bridge is not only the most popular place to commit suicide in the United

States but also the most popular in the entire world.[43] The deck is approximately 245 feet (75 m)

above the water.[44] After a fall of approximately four seconds, jumpers hit the water at some

76 miles per hour (122 km/h). At such a speed, water has been determined to take on properties

similar to concrete. Because of this, most jumpers die on their immediate contact with the water.

The few who survive the initial impact generally drown or die of hypothermia in the cold water.

An official suicide count was kept, sorted according to which of the bridge's 128 lamp posts the

jumper was nearest when he or she jumped. By 2005, this count exceeded 1,200 and new

suicides were averaging one every two weeks.[45] For comparison, the reported second-most-

popular place to commit suicide in the world, Aokigahara Forest in Japan, has a record of 78

bodies, found within the forest in 2002, with an average of 30 a year. [46] There were 34 bridge-

jump suicides in 2006 whose bodies were recovered, in addition to four jumps that were

witnessed but whose bodies were never recovered, and several bodies recovered suspected to be

from bridge jumps. The California Highway Patrol removed 70 apparently suicidal people from

the bridge that year.[47]

There is no accurate figure on the number of suicides or successful jumps since 1937, because

many were not witnessed. People have been known to travel to San Francisco specifically to

jump off the bridge, and may take a bus or cab to the site; police sometimes find abandoned

rental cars in the parking lot. Currents beneath the bridge are very strong, and some jumpers have

undoubtedly been washed out to sea without ever being seen. The water may be as cold as 47 °F

(8 °C).

The fatality rate of jumping is roughly 98%. As of 2006, only 26 people are known to have

survived the jump.[45] Those who do survive strike the water feet-first and at a slight angle,

although individuals may still sustain broken bones or internal injuries. One young man survived

a jump in 1979, swam to shore, and drove himself to a hospital. The impact cracked several of

his vertebrae.[48]

Engineering professor Natalie Jeremijenko, as part of her Bureau of Inverse Technology art

collective, created a "Despondency Index" by correlating the Dow Jones Industrial Average with

the number of jumpers detected by "Suicide Boxes" containing motion-detecting cameras, which

she claimed to have set up under the bridge.[49] The boxes purportedly recorded 17 jumps in three

months, far greater than the official count. The Whitney Museum, although questioning whether

Jeremijenko's suicide-detection technology actually existed, nevertheless included her project in

its prestigious Whitney Biennial.[50]

Various methods have been proposed and implemented to reduce the number of suicides. The

bridge is fitted with suicide hotline telephones, and staff patrol the bridge in carts, looking for

people who appear to be planning to jump. Iron workers on the bridge also volunteer their time

to prevent suicides by talking or wrestling down suicidal people.[51] The bridge is now closed to

pedestrians at night. Cyclists are still permitted across at night, but must be buzzed in and out

through the remotely controlled security gates.[52] Attempts to introduce a suicide barrier had

been thwarted by engineering difficulties, high costs, and public opposition. [53] One recurring

proposal had been to build a barrier to replace or augment the low railing, a component of the

bridge's original architectural design. New barriers have eliminated suicides at other landmarks

around the world, but were opposed for the Golden Gate Bridge for reasons of cost, aesthetics,

and safety (the load from a poorly designed barrier could significantly affect the bridge's

structural integrity during a strong windstorm).

Strong appeals for a suicide barrier, fence, or other preventive measures were raised once again

by a well-organized vocal minority of psychiatry professionals, suicide barrier consultants, and

families of jumpers after the release of the controversial 2006 documentary film The Bridge, in

which filmmaker Eric Steel and his production crew spent one year (2004) filming the bridge

from several vantage points, in order to film actual suicide jumps. The film caught 23 jumps,

most notably that of Gene Sprague as well as a handful of thwarted attempts. The film also

contained interviews with surviving family members of those who jumped; interviews with

witnesses; and, in one segment, an interview with Kevin Hines who, as a 19-year-old in 2000,

survived a suicide plunge from the span and is now a vocal advocate for some type of bridge

barrier or net to prevent such incidents from occurring.

On October 10, 2008, the Golden Gate Bridge Board of Directors voted 14 to 1 to install a

plastic-covered stainless-steel net below the bridge as a suicide deterrent. The net will extend

20 feet (6 m) on either side of the bridge and is expected to cost $40–50 million to complete. [54]

[55] However, lack of funding could delay the net's construction.[56]

Wind

Air show over Golden Gate Bridge

Since its completion, the Golden Gate Bridge has been closed due to weather conditions only

three times: on 1 December 1951, because of gusts of 69 mph (111 km/h); on 23 December

1982, because of winds of 70 mph (113 km/h); and on 3 December 1983, because of wind gusts

of 75 mph (121 km/h).[57]

Seismic retrofit

Modern knowledge of the effect of earthquakes on structures led to a program to retrofit the

Golden Gate to better resist seismic events. The proximity of the bridge to the San Andreas Fault

places it at risk for a significant earthquake. Once thought to have been able to withstand any

magnitude of foreseeable earthquake, the bridge was actually vulnerable to complete structural

failure (i.e., collapse) triggered by the failure of supports on the 320-foot (98 m) arch over Fort

Point.[58] A $392 million program was initiated to improve the structure's ability to withstand

such an event with only minimal (repairable) damage. The retrofit's planned completion date is

2012.[59][60]

Doyle Drive replacement project

The elevated approach to the Golden Gate Bridge through the San Francisco Presidio is

popularly known as Doyle Drive. Doyle Drive, dating back to 1933, was named after Frank P.

Doyle, director of the California State Automobile Association.[61] The highway carries

approximately 91,000 vehicles each weekday between downtown San Francisco and suburban

Marin County.[62] However, the road has been deemed "vulnerable to earthquake damage", has a

problematic 4-lane design, and lacks shoulders. For these reasons, a San Francisco County

Transportation Authority study recommended that the current outdated structure be replaced with

a more modern, efficient, and multimodal transportation structure. Construction on the $1

billion[63] replacement, known as the Presidio Parkway, began in December 2009 [64] and is

expected to be completed in 2013.

Øresund Bridge

Official name Øresundsbroen, Öresundsbron

CarriesFour lanes of European route E20

Double track Oresund Railway Line

Crosses Oresund strait (The Sound)

LocaleCopenhagen, Denmark and Malmö,

Sweden

Designer Georg Rotne

Design Cable-stayed bridge

Total length 7,845 metres (25,738 ft)

Width 23.5 metres (77.1 ft)

Longest span 490 metres (1,608 ft)

Clearance

below57 metres (187 ft)

Opened July 2, 2000

Toll 285DKK[1] /375SEK[2] /39EUR[3]

Daily traffic ca. 17,000 road vehicles

Coordinates55°34′31″N 12°49′37″E /

55.57528°N 12.82694°E

The Øresund or Öresund Bridge (Danish: Øresundsbroen, Swedish: Öresundsbron, joint

hybrid name: Øresundsbron) is a combined twin-track railroad and four-lane highway bridge-

tunnel across the Öresund strait. The Øresund Bridge connects Sweden and Denmark, and it is

the longest highway and railroad bridge in Europe. The Øresund Bridge also connects two major

Metropolitan Areas: those of the Danish capital city of Copenhagen and the major Swedish city

of Malmö. Furthermore, the Øresund Bridge connects the highway network of Scandinavia with

those of Central and Western Europe

The international European route E20 crosses this bridge-tunnel via the roadway, and the

Öresund Railway Line uses the railroads. The construction of the Great Belt Fixed Link – which

connects Zealand to Funen and whence to the Jutland Peninsula – and the Øresund Bridge have

connected Western and Central Europe to Scandinavia. The Øresund Bridge was designed by the

Danish architectural practice Dissing+Weitling.

The purpose for the additional expenditure and complexity related to digging a tunnel for part of

the way – rather than simply raising that section of the bridge – was to avoid interfering with

airliners from the nearby Copenhagen International Airport, and also to provide a clear channel

for ships in good weather or bad, and to prevent ice floes from blocking the strait. The Øresund

Bridge crosses the border between Denmark and Sweden, but according to the Schengen

Agreement and the Nordic Passport Union, there are usually no passport inspections. There are

customs checks at the entrance toll booths for entering Sweden, but not for entering Denmark.

Name

In Sweden and Denmark the bridge is most often referred to as Öresundsbron and

Øresundsbroen, respectively. The bridge company itself insists on Øresundsbron, a compromise

between the two languages. This symbolises a common cultural identity for the region, with

some of the people considering themselves "Öresund citizens" once the Øresund Bridge was

completed. Since the crossing is actually composed of a bridge, one artificial island, and a

tunnel, it is sometimes called the "Öresund Link" or the "Öresund Connection" (Danish:

Øresundsforbindelsen, Swedish: Öresundsförbindelsen).

The phrase The Sound Bridge is occasionally heard, using the historic English name for the

strait.

History

The construction of the Øresund Bridge began in 1995. It was finished about August 14, 1999.

Crown Prince Frederik of Denmark and Crown Princess Victoria of Sweden met midway across

the bridge-tunnel to celebrate its completion. Its official dedication took place on July 1, 2000,

with Queen Margrethe II, and King Carl XVI Gustaf as the host and hostess of the ceremony.

The bridge-tunnel was opened for public traffic later that day. On 12 June 2000, two weeks

before the dedication, 79,871 runners competed in a half marathon (Broloppet, the Bridge Run)

from Amager, Denmark, to Skåne, Sweden.

In spite of two schedule setbacks – the discovery of 16 unexploded World War II bombs lying on

the seafloor and an inadvertently skewed tunnel segment – the bridge-tunnel was finished three

months ahead of schedule.

Initially, the crossing was not used as much as expected, probably because of the high tolls.

Since 2005, there has been a rapid increase in traffic. This may have been caused by Danes

buying homes in Sweden – to take advantage of lower housing prices in Malmö – and

commuting to work in Denmark. In 2008, to cross by car cost DKK 260, SEK 325, or € 36.30,

although discounts up to 75% are available for regular users. In 2007, almost 25 million people

traveled over the Øresund Bridge: 15.2 million by car and bus, and 9.6 million by train.

Link features

The bridge

Aerial Photo of Oresund Bridge.

At 7,845 m (25,738 ft), the bridge covers half the distance between Sweden and the Danish

island of Amager, the border between the two countries being located 5.3 km (3.3 mi) from the

Swedish end. The structure has a mass of 82,000 tonnes and supports two railroad tracks beneath

four road lanes in a horizontal girder extending along the entire length of the bridge. On both

approaches to the three cable-stayed bridge sections, the girder is supported every 140 m (459 ft)

by concrete piers. The two pairs of free-standing cable supporting towers are 204 m (669 ft) high

allowing shipping 57 m (187 ft) of head room under the main span. Even so, most ship's captains

prefer to pass through the unobstructed Drogden Strait above the Drogden Tunnel. Its 491 m

(1,611 ft) cable-stayed main span is the longest of this type in the world. A girder and cable-

stayed design was chosen to provide the rigidity necessary to carry heavy railroad traffic, and

also to resist large accumulations of ice..

Peberholm

The bridge joins the Drogden tunnel on the artificial island christened Peberholm (Pepper Islet).

With characteristic good humour, the Danes chose the name to complement the natural island of

Saltholm (salt islet) just to the north. They also made Peberholm a designated nature reserve.

Built from Swedish rock and the soil dredged up during the bridge and tunnel construction,

Peberholm is approximately 4 km (2.5 mi) long, with an average width of 500 m (1,640 ft).

Drogden Tunnel

Cross-section of the Oresund Tunnel

The connection between the artificial island of Peberholm and the artificial peninsula at Kastrup

on Amager island – the nearest populated part of Denmark – is through the Drogden Tunnel

(Drogdentunnelen). The 4,050 m (13,287 ft) long tunnel comprises a 3,510 m (11,516 ft)

undersea tube tunnel plus 270 m (886 ft) entry tunnels at each end. The tube tunnel is made from

20 prefabricated reinforced concrete segments – the most massive in the world at 55,000 tonnes

each – interconnected in a trench dug in the seabed. Two tubes in the tunnel carry railway tracks;

two more carry roads while a small fifth tube is provided for emergencies. The tubes are

arranged side by side.

Rail transport

Satellite image of the Oresund Bridge

The public transport rail system is operated jointly by the Swedish SJ and the Danish via

DSBFirst on a commission by Skånetrafiken and other county traffic companies (that also sell

tickets) and the Danish transport agency. A series of new dual-voltage trains were developed

which link the Copenhagen area with Malmö and southern Sweden as far as Gothenburg and

Kalmar on selected schedules. SJ operate the X2000 and InterCity trains over the bridge with

connections to Gothenburg and Stockholm. DSB operate trains to Ystad that connect directly to a

ferry to Bornholm. Copenhagen Airport at Kastrup is served by its own train station close to the

western bridgehead. Trains operate every 20 minutes over the crossing and once an hour during

the night in both directions. An additional couple of Øresundstrains are operated at rush hour,

and 1-2 per hour and direction SJ trains and DSB trains every other hour. Freight trains also use

the crossing.

The rail connection has become popular and is now experiencing congestion. The congestion is

mainly on land and not really on the bridge. The railway stations on both sides of the bridge,

especially the Malmö Central Station, are the main sources of congestion. People have to stand

onboard during rush hour since it is hard to run more trains. The new Malmö City Tunnel and its

stations will relieve the congestion on the Swedish side.

The rail section is double track standard gauge (1435 mm; 4 ft 81⁄2 in) and capable of high-speeds

up to 200 kilometres per hour (120 mph), but slower in Denmark, especially in the tunnel

section. There were challenges related to the difference in electrification and signaling between

the Danish and Swedish railway networks. The solution chosen is to switch the electrical system,

from Swedish 15 kV, 16.7 Hz to Danish 25 kV, 50 Hz AC right before the eastern bridgehead at

Lernacken in Sweden. The line is signaled according to the standard Swedish system across the

length of the bridge. On Peberholm, the line switches to Danish signaling which continues into

the tunnel. Sweden runs railways with left-hand traffic and Denmark with right-hand traffic. The

switch is made at the Malmö Central Station, which is also a terminus. For the new Malmö City

Tunnel connection a flyover will pass one track over to the other side.

Costs

In the tunnel

The cost for the entire Øresund Connection construction, including motorway and railway

connections on land, was calculated at DKK 30.1 billion according to the 2000 year price index,

with the cost of the bridge paid back by 2035. In 2006 Sweden began spending a further SEK

9.45 billion on the Malmö City Tunnel as a new rail connection to the bridge; it is due for

completion in 2010.

The connection will be entirely user financed. The owner company is owned half by the Danish

government and half by the Swedish government. This owner company has taken loans

guaranteed by the governments to finance the connection, and the user fees are the only incomes

for the company. After the increase in traffic these fees are enough to pay the interest and begin

paying back the loans, which is expected to take about 30 years.

The tax payers have not paid for the bridge and the tunnel. However, tax money has been used

for the land connections. Especially on the Danish side the land connection has domestic benefit,

mainly connecting the airport to the railway network. The Malmö City Tunnel has the benefit of

connecting the southern part of the inner city to the rail network and allowing many more trains

to and from Malmö.

Toll charge

In April 2009, the toll for driving the fixed link was as follows (one way trip without discount) in

Danish kroner (DKK), Swedish kronor (SEK) and euro (EUR):

Vehicle DKK[1] SEK[2] EUR[3]

Motorcycle 150 215 21

Standard car 275 380 39

Motorhome/car+caravan 550 790 75

Minibus (6-9 metres) 550 790 75

Bus (longer than 9 metres) 1145 1675 157

Lorry/truck (9-20 metres) 795 1170 109

Lorry/truck (over 20 metres) 1190 1755 163

Train ticket[4] 78 98 9

There has been criticism of the tolls which are much higher than what many consider reasonable

for a bridge. However they are comparable with the ferry charges that were levied before the

bridge was built and for the ferries still running between Helsingborg and Helsingør.

Radio masts and towersFrom Wikipedia, the free encyclopediaJump to: navigation, search

Masts of the Rugby VLF transmitter in England

A dismantled radio mast in sections

Radio masts and towers are, typically, tall structures designed to support antennas (also known as aerials) for telecommunications and broadcasting, including television. They are among the tallest man-made structures. Similar structures include electricity pylons and towers for wind turbines.

Masts are sometimes named after the broadcasting organisations that use them, or after a nearby city or town.

The Warsaw Radio Mast was the world's tallest supported structure on land, but it collapsed in 1991, leaving the KVLY/KTHI-TV mast as the tallest.

In the case of a mast radiator or radiating tower, the whole mast or tower is itself the transmitting antenna.

[edit] Mast or tower?

A radio mast base showing how virtually all support is provided by the guy-wires

The terms "mast" and "tower" are often used interchangeably. However, in structural engineering terms, a tower is a self-supporting or cantilevered structure, while a mast is held up by stays or guys. Masts tend to be cheaper to build but require an extended area surrounding them to accommodate the stay blocks. Towers are more commonly used in cities where land is in short supply.

There are a few borderline designs which are partly free-standing and partly guyed. For example:

The Gerbrandy tower consists of a self-supporting tower with a guyed mast on top. The few remaining Blaw-Knox towers do the opposite: they have a guyed lower section

surmounted by a freestanding part. Zendstation Smilde a tall tower with a guyed mast on top (guys go to ground) Torre de Collserola a guyed tower, with a guyed mast on top. (Tower portion is not free-

standing.)

[edit] Materials

[edit] Steel lattice

Steel lattice tower

The steel lattice is the most widespread form of construction. It provides great strength, low wind resistance and economy in the use of materials. Such structures are usually triangular or square in cross-section.

When built as a stayed mast, usually the whole mast is parallel-sided. One exception is the Blaw-Knox type.

When built as a tower, the structure may be parallel-sided or taper over part or all of its height. When constructed of several sections which taper exponentially with height, in the manner of the Eiffel Tower, the tower is said to be an Eiffelized one. The Crystal Palace tower in London is an example.

[edit] Tubular steel

Some masts are constructed out of steel tubes. In the UK, these were the subject of collapses at the Emley Moor and Waltham TV stations in the 1960s.

At several cities in Russia and Ukraine, guyed masts were built between 1960 and 1965 with crossbars running from the mast structure to the guys. All these masts are tubular structures, used exclusively for FM/TV transmission. Except for the mast in Vinnytsia, these masts have heights between 150 and 200 metres.

First modern TV Tower in Stuttgart

[edit] Reinforced concrete

Reinforced concrete towers are relatively expensive to build but provide a high degree of mechanical rigidity in strong winds. This can be important when antennas with narrow beamwidths are used, such as those used for microwave point-to-point links, and when the structure is to be occupied by people.

In the 1950s, AT&T built numerous concrete towers, more resembling silos than towers, for its first transcontinental microwave route. Many are still in use today.

In Germany and the Netherlands most towers constructed for point-to-point microwave links are built of reinforced concrete, while in the UK most are lattice towers.

Concrete towers can form prestigious landmarks, such as the CN Tower in Toronto. As well as accommodating technical staff, these buildings may have public areas such as observation decks or restaurants.

The Stuttgart TV tower was the first tower in the world to be built in reinforced concrete. It was designed in 1956 by the local civil engineer Fritz Leonhardt.

Tokyo Tower

[edit] Fibreglass

Fibreglass poles are occasionally used for low-power non-directional beacons or medium-wave broadcast transmitters.

[edit] Wood

There are fewer wooden towers now than in the past. Many were built in the UK during World War II because of a shortage of steel. In Germany before World War II wooden towers were used at nearly all medium-wave transmission sites, but all of these towers have since been demolished, except for the Gliwice Radio Tower.

Ferryside Relay is an example of a TV relay transmitter using a wooden pole.

[edit] Other types of antenna supports and structures

[edit] Poles

Shorter masts may consist of a self-supporting or guyed wooden pole, similar to a telegraph pole. Sometimes self-supporting tubular galvanized steel poles are used: these may be termed monopoles.

[edit] Buildings

In some cases, it is possible to install transmitting antennas on the roofs of tall buildings. In North America, for instance, there are transmitting antennas on the Empire State Building, the Sears Tower, and formerly on the World Trade Center towers. When the buildings collapsed, several local TV and radio stations were knocked off the air until backup transmitters could be put into service.[1] Such facilities also exist in Europe, particularly for portable radio services and low-power FM radio stations.

[edit] Disguised cell-sites

Completed in December 2009 at Epiphany Lutheran Church in Lake Worth, Florida, this 100' tall cross conceals equipment for T-Mobile.

Many people view bare cellphone towers as ugly and an intrusion into their neighbourhoods. Even though people increasingly depend upon cellular communications, they are opposed to the bare towers spoiling otherwise scenic views. Many companies offer to 'hide' cellphone towers in, or as, trees, church towers, flag poles, water tanks and other features.[2] There are many providers that offer these services as part of the normal tower installation and maintenance service. These are generally called "stealth towers" or "stealth installations".

The level of detail and realism achieved by disguised cellphone towers is remarkably high; for example, such towers disguised as trees are nearly indistinguishable from the real thing, even for local wildlife (who additionally benefit from the artificial flora).[3] Such towers can be placed unobtrusively in national parks and other such protected places, such as towers disguised as cacti in Coronado National Forest.[4]

Even when disguised, however, such towers can create controversy; a tower doubling as a flagpole attracted controversy in 2004 in relation to the U.S. Presidential campaign of that year, and highlighted the sentiment that such disguises serve more to allow the installation of such towers in subterfuge away from public scrutiny rather than to serve towards the beautification of the landscape.[original research?][5]

[edit] Mast radiators

Main article: Mast radiator

A mast radiator is a radio tower or mast in which the whole structure works as an antenna. It is used frequently as a transmitting antenna for long or medium wave broadcasting.

Structurally, the only difference is that a mast radiator may be supported on an insulator at its base. In the case of a tower, there will be one insulator supporting each leg.

[edit] Telescopic, pump-up and tiltover towers

Main article: Cell on wheels

A special form of the radio tower is the telescopic mast. These can be erected very quickly. Telescopic masts are used predominantly in setting up temporary radio links for reporting on major news events, and for temporary communications in emergencies. They are also used in tactical military networks. They can save money by needing to withstand high winds only when raised, and as such are widely used in amateur radio.

Telescopic masts consist of two or more concentric sections and come in two principal types:

Pump-up masts are often used on vehicles and are raised to their full height pneumatically or hydraulically. They are usually only strong enough to support fairly small antennas.

Telescopic lattice masts are raised by means of a winch, which may be powered by hand or an electric motor. These tend to cater for greater heights and loads than the pump-up type. When retracted, the whole assembly can sometimes be lowered to a horizontal position by means of a second tiltover winch. This enables antennas to be fitted and adjusted at ground level before winching the mast up.

[edit] Balloons and kites

A tethered balloon or a kite can serve as a temporary support. It can carry an antenna or a wire (for VLF, LW or MW) up to an appropriate height. Such an arrangement is used occasionally by military agencies or radio amateurs. The American broadcasters TV Martí broadcast a television program to Cuba by means of such a balloon.

[edit] Other special structures

For two VLF transmitters wire antennas spun across deep valleys are used. The wires are supported by small masts or towers or rock anchors. See List of spans: Antenna spans across valleys. The same technique was also used for the Criggion VLF transmitter.

For ELF transmitters ground dipole antennas are used. Such structures require no tall masts. They consist of two electrodes buried deep in the ground at least a few dozen kilometres apart. From the transmitter building to the electrodes, overhead feeder lines run. These lines look like power lines of the 10 kV level, and are installed on similar pylons.

[edit] Design features

[edit] Economic and aesthetic considerations

A radio amateur's do it yourself steel-lattice tower

Felsenegg-Girstel TV-tower

Uetliberg TV-tower

Communications tower, camouflaged as a slim tree The cost of a mast or tower is roughly proportional to the square of its height.[citation needed]

A guyed mast is cheaper to build than a self-supporting tower of equal height. A guyed mast needs additional land to accommodate the guys, and is thus best suited to

rural locations where land is relatively cheap. An unguyed tower will fit into a much smaller plot.

A steel lattice tower is cheaper to build than a concrete tower of equal height. Two small towers may be less intrusive, visually, than one big one, especially if they look

identical. Towers look less ugly if they and the antennas mounted on them appear symmetrical. Concrete towers can be built with aesthetic design - and they are, especially in

Continental Europe. They are sometimes built in prominent places and include observation decks or restaurants.

[edit] Masts for HF/shortwave antennas

For transmissions in the shortwave range, there is little to be gained by raising the antenna more than a few wavelengths above ground level. Shortwave transmitters rarely use masts taller than about 100 metres.

[edit] Access for riggers

Because masts, towers and the antennas mounted on them require maintenance, access to the whole of the structure is necessary. Small structures are typically accessed with a ladder. Larger structures, which tend to require more frequent maintenance, may have stairs and sometimes a lift, also called a service elevator.

[edit] Aircraft warning features

Tall structures in excess of certain legislated heights are often equipped with aircraft warning lamps, usually red, to warn pilots of the structure's existence. In the past, ruggedized and under-run filament lamps were used to maximize the bulb life. Alternatively, neon lamps were used. Nowadays such lamps tend to use LED arrays.

Height requirements vary across states and countries, and may include additional rules such as requiring a white flashing strobe in the daytime and pulsating red fixtures at night. Structures over a certain height may also be required to be painted with contrasting color schemes such as white and orange or white and red to make them more visible against the sky.

[edit] Light pollution and nuisance lighting

In some countries where light pollution is a concern, tower heights may be restricted so as to reduce or eliminate the need for aircraft warning lights. For example in the United States the 1996 Telecommunications Act allows local jurisdictions to set maximum heights for towers, such as limiting tower height to below 200 feet and therefore not requiring aircraft illumination under FCC rules. The limit is more commonly set to 190 or 180 feet to allow for masts extending above the tower.

[edit] Wind-induced oscillations

One problem with radio masts is the danger of wind-induced oscillations. This is particularly a concern with steel tube construction. One can reduce this by building cylindrical shock-mounts into the construction. One finds such shock-mounts, which look like cylinders thicker than the mast, for example, at the radio masts of DHO38 in Saterland. There are also constructions, which consist of a free-standing tower (usually from reinforced concrete), onto which a guyed radio mast is installed. The best known such construction is the Gerbrandy Tower in Lopik (the Netherlands). Further towers of this building method can be found near Smilde (the Netherlands) and Fernsehturm, Waldenburg, Baden-Württemberg, Germany).

[edit] Hazard to birds

Radio, television and cell towers have been documented to pose a hazard to birds. Reports have been issued documenting known bird fatalities and calling for research to find ways to minimize the hazard that communications towers can pose to birds.[6][7]

[edit] Catastrophic collapses

Main article: List of catastrophic collapses of radio masts and towers

[edit] Law

Since June 2010, Telecom operators in the USA can erect new telecom masts or towers as the government has lifted the moratorium, which was earlier placed on the issuance of permits for the construction of telecommunication towers.[8]