BGuthrie Photos: CA -- San Francisco -- Golden Gate Bridge (South Side) Visitor Center

CA -- San Francisco -- Golden Gate Bridge (South Side) Visitor Center:

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Specific picture descriptions: Photos above with "i" icons next to the bracketed sequence numbers (e.g. "[1] ") are described as follows:
1. GGBSVC_180715_002.JPG: Men of Vision
2. GGBSVC_180715_016.JPG: 1870 Joseph b. Strauss 1938 "The Man Who Built the Bridge" Here at the golden gate is the eternal rainbow that he conceived and set to form a promise indeed that the race of man shall endure unto the ages. Chief engineer of the Golden Gate Bridge 1929 - 1937
3. GGBSVC_180715_053.JPG: The Golden Gate Bridge
4. GGBSVC_180715_066.JPG: The Bridge
5. GGBSVC_180715_076.JPG: A Man Possessed
6. GGBSVC_180715_081.JPG: High Style
7. GGBSVC_180715_083.JPG: A Span Too Far
8. GGBSVC_180715_087.JPG: Spinning Cables
9. GGBSVC_180715_093.JPG: Heroic Efforts
10. GGBSVC_180715_097.JPG: Staggering Statistics
11. GGBSVC_180715_106.JPG: Test Tower
12. GGBSVC_180715_112.JPG: Mind the Gap
13. GGBSVC_180715_115.JPG: Save the Fort
14. GGBSVC_180715_124.JPG: 81 GGB
15. GGBSVC_180715_163.JPG: How the Bridge Vibrates Suspension bridges vibrate during earthquakes and strong winds. This 1:500 scale model of the Golden Gate Bridge displays vibration patterns (also known as vibration modes) inherent in suspension bridges. Chain is used to model the cables and segmented pieces are used to model the roadway deck, so the vibration patterns are exaggerated and more easily seen. Swaying in the wind On the model, push the CENTER SPAN area to one side and release. This is the fundamental transverse vibration mode. The Golden Gate Bridge takes about 20 seconds to complete one back-and-forth swing. The amount of time to complete one back-and-forth cycle is the period of vibration. Very large and heavy structures like the Golden Gate Bridge move slowly and therefore have long periods of vibration. The model is smaller and lighter than the actual Bridge, so it vibrates faster. When steady westerly winds blow across the Bridge deck, they push the deck to the east, usually bending or bowing a few feet, or about a meter. For very strong winds, the deck is designed to bow horizontally at the middle of the center span 27.7 feet (8.4 meters). Wind Flutter Twist and pull down on the CENTER SPAN area. Notice how the deck on either side twists in the opposite direction. Twist and pull down on the deck section labeled 1/4 SPAN. Notice how the deck on the opposite side twists in the other direction. This pattern of twisting, or torsional vibration mode, led to the collapse of the Tacoma Narrows Bridge in 1940. Vertical Vibration Press down on the CENTER SPAN and quickly release it. Notice the deck oscillates or vibrates up and down about 2 times per second. This is the fundamental vertical vibration mode of this model. The Golden Gate Bridge, 500 times larger, takes about 8 seconds to complete one cycle of this oscillation. Earthquake Shake the ANCHORAGE area back and forth. Notice how waves travel along the deck. Try shaking faster and slower. Which rate makes the bridge model move more? Bridges respond or resonate more intensely to earthquakes when the ground shaking motion matches the period of vibration of the bridge.
16. GGBSVC_180715_183.JPG: When It's Foggy... When it's foggy you can hear the sound from the south tower instantly by telephone, 415-202-3809. Then, wait about 2 seconds to hear the sound waves reach your ears through the air, traveling a little faster than a jet airliner. The south tower foghorn sounds a deep, loud note for 2 seconds, then it repeats in 18 seconds. Another foghorn at midspan between the towers sounds a pair of high-pitched notes. Fog is formed when the moist air over the ocean is cooled by cold water currents along Northern California's coast. The water vapor cools and condenses into tiny water droplets – fog. Fog is most common in the summer, when the air over the interior land heats up more than over the ocean. Warm air is less dense and exerts less pressure than cooler air, allowing the cooler ocean air to push its way in through the Golden Gate. Why does the fog come through the Golden Gate? It is the only sea-level gap in the coastal mountain range for hundreds of miles. It is a canyon cut through the mountains by an ancient river. Water stored as ice melted as the last Ice Age ended, raising the sea level. Today, the bottom of that canyon is over 300 feet (90 meters) below the waves.
17. GGBSVC_180715_186.JPG: Fort Point Arch The curve of an arch experiences pushing forces, or compression. At the south (San Francisco) end of the suspension bridge, a large steel arch carries the roadway deck over Fort Point, the brick fort below. Fort Point was completed in 1861, long before the Golden Gate Bridge was constructed in the 1930s. The chief engineer planning the new bridge, Joseph Strauss, preserved the historic fort by spanning over it with an arch bridge. A suspension bridge is the structural opposite of an arch. The curving cables of a suspension bridge are in tension, experiencing pulling forces. The opposite or upside down picture of those curves looks like an arch. The forces in the arch, compression forces, are the opposite of the tension forces that the suspension bridge cables experience. A tension force is a force that pulls. The curving cables pull on anchorages at the two ends of a suspension bridge. Those anchorages embedded in the earth must supply reaction forces, exerted outward, to withstand the tension in the cables that tries to pull the anchorages inward.
18. GGBSVC_180715_201.JPG: Making the impossible, possible; the story of the Golden Gate Bridge
19. GGBSVC_180715_205.JPG: Bridging the Gate - The Beginning San Francisco grew rapidly in the early 1900s, but the mile-wide Golden Gate Strait limited access and development to the north. Traveling north to Marin County and the Redwood Empire beyond required a lengthy trip by ferryboat. In 1923, popular support to build a bridge across the strait united behind the slogan "Bridge the Gate." Bridge supporters convinced the California state legislature to create a special district, the Golden Gate Bridge and Highway District, as the entity to finance, build, and operate such a bridge. In 1928, the District was incorporated and included the counties of San Francisco, Marin, Sonoma, Del Norte, and parts of Napa and Mendocino. A bridge over the Golden Gate Strait was the ambition of Joseph B. Strauss, who overcame many obstacles to secure official approvals and win public support. Strauss faced strong opposition from ferry operators, conservationists, and even some in the engineering community. He assembled and directed an outstanding team of engineers, architects, geologists, and construction workers to design and build a bridge that set a world record for longest span (the distance spanned between the towers) and united a growing metropolis.
20. GGBSVC_180715_210.JPG: Engineering the Design In 1921, engineer Joseph B. Strauss submitted a design for a bridge that would cross the Golden Gate Strait -- a hybrid bridge with a suspension span supported at each end by cantilever trusses. By 1929, consulting engineers Leon S. Moisseiff and O.H. Ammann had persuaded Strauss to accept the more graceful all-suspension bridge design that we see today. Strauss assigned engineer Charles A. Ellis to work in collaboration with Moisseiff to perform the calculations needed to complete the design, which was complex and challenging work done without modern computers. The most common "calculator" that structural engineers used in that era was a slide rule, and drafting was done with pencil and paper on drawing boards. The engineers relied on recent advances in suspension bridge design theory. They verified those calculations with tests on a steel tower model of 1:56 scale (56 times smaller than one of the actual towers). The tests confirmed that the tower calculations were sound. The geology of the south tower location was investigated before construction could begin. The south tower was planned for construction over 1,100 feet (335 meters) offshore on serpentine rock. Consulting geologist Andrew C. Lawson oversaw a load test performed by placing weight equivalent to a fully loaded railroad boxcar on an area of serpentine rock only 20 inches (508 millimeters) square. The rock was more than strong enough.
21. GGBSVC_180715_214.JPG: Working Under Water One of the greatest construction challenges took place underwater. The south tower was located more than 1,100 feet (335 meters) from the San Francisco shore. To build the south tower structures, divers played a critical role descending up to 110 feet (33 meters) into the tumultuous waters of the Golden Gate Strait. They placed dynamite charges and removed loose material down to bedrock with high-pressure hoses. Later, they descended to guide the positioning of the forms and funnels used to place the concrete for the south tower fender. Divers worked in water that was dark, murky and cold, and only when the tide changed and the usually strong currents lessened, which occurred four times in a day. Portable air tanks for diving had not yet been invented. A diver's life depended on the continuous pumping of air through a long hose to the surface.
22. GGBSVC_180715_219.JPG: A Bathtub for the South Tower To reach the site of the south tower foundation, workers constructed a temporary roadway on a timber access trestle, or wharf, from the San Francisco shore. The dangers of the exposed location soon became apparent in 1933, when a freighter collided with the trestle. Two months later, over half of the repaired structure collapsed in a storm. Undaunted, the engineers and workers restored the structure and continued their work. The plans called for a huge oval-shaped concrete barrier, or fender, to protect the base of the south tower from ship collisions during fog. To build the fender, workers placed the concrete through tubes underwater into wood forms, where it set. When the fender was built up above the water level and was visible, the workers called it a "giant bathtub." For the foundation pier, the base on which the tower would stand, workers placed concrete underwater to fill the bottom portion of the fender. After pumping out the remaining 9.4 million gallons (35.6 million liters) of seawater, workers inside the "bathtub" completed the placement of reinforcing steel and concrete. Once the concrete work was done, the erection of the steel for the south tower began in January 1935 and was completed in just six months.
23. GGBSVC_180715_226.JPG: World's Tallest Bridge Towers A long-span suspension bridge usually has tall towers. The height of the Bridge's towers directs the tensile (pulling) forces in the main cables upward, so that the cables can efficiently do their job of holding up the roadway deck. The 746-foot-tall (227-meter-tall) towers, the tallest bridge towers in the world when the Bridge was completed in 1937, were constructed by lifting prefabricated steel sections into place. A temporary support for cranes (climbing derrick) was built between the two legs of each tower, and cranes on the platform lifted sections of the tower into place at that level. Then the platform with its cranes was raised up the growing tower, and the process was repeated. The 44,000 tons (40,000 metric tons) of steel in each tower was manufactured at Bethlehem Steel plants in Pennsylvania. The steel was shipped through the Panama Canal to the San Francisco Bay. With the towers rising higher than a 60-story building – this was no place for a person with a fear of heights.
24. GGBSVC_180715_228.JPG: Spinning the Main Cables By mid-1935, the north and south towers stood ready to support the two main cables. Each of the cables measured a little over 3 feet (about 1 meter) in diameter and weighed 12,000 tons. They were far too heavy to carry across the Golden Gate Strait on barges and lift up to the tops of the towers. The cables were constructed high in the air using a process called cable spinning, which was invented by John A. Roebling in the 1800s. The company he founded made cables for the Golden Gate Bridge. To spin the cables, workers pulled a wire, about as thick as a pencil, from the concrete anchorage at one shore, up and over both towers, and on to the other anchorage. The wire was then secured and sent back. It took many back-and-forth trips to place the 27,572 wires that are in each cable. Individual wires were grouped into heavier strands and compacted together to form the finished cable. The spinning of the cables took just six months and nine days, setting records for speed and efficiency. The entire weight of the roadway deck crossing the Gate could then be suspended from the two cables – that's why it is called a suspension bridge.
25. GGBSVC_180715_232.JPG: Hanging the Roadway Deck The steel trusses on each side of the roadway deck structure along its length can be identified by their triangles. The trusses support beams holding up the roadway and stiffen the deck structure against wind. They span 50 feet (15 meters) between the vertical steel suspender ropes that support them. The vertical suspenders pull the weight of the deck, along with its traffic, up to the main cables. When installed, the 250 pairs of suspender ropes looked like strings on a giant harp. An advantage of a suspension bridge is that once the towers, anchorages, and main cables are installed, no temporary supports are needed under the bridge to build the roadway deck. The deck is built in sections, proceeding out from the towers in a balanced way, each section hung from the suspenders. The final piece of the overall structure, the roadway deck structure with its paving, was in place by April 19, 1937, about a month before the Bridge opened.
26. GGBSVC_180715_237.JPG: All In A Day's Work Bridge construction began in 1933, in the midst of the Great Depression. The unemployment rate was 25 percent, and jobs were much sought after. With the exception of highly specialized jobs, the Bridge was built by local labor. Besides the pay, the men working on the Bridge had a special incentive. They knew they were building more than just another bridge: this was going to be one of the greatest works of modern engineering. The weather was often cold, windy, and foggy. Work had to go on inside cramped spaces. Climbing up and walking high atop the Bridge was as dangerous as it was scary. Safety was a priority. Workers wore helmets, special wind goggles, and headlamps for the dark, enclosed areas - a first in bridge construction. The undercoat of paint, the primer, contained lead to prevent the steel from rusting. Workers wore respirators to protect them from lead fumes released during the installation of red-hot rivets. Today, the paints used on the Bridge contain no lead. Another first in bridge building was the installation of a safety net during construction. The 19 men who fell and were saved by the net called themselves the Halfway to Hell Club. The Bridge had only one fatality until February 1937. Then a heavy scaffold fell through the net, causing 10 men to fall through to their deaths. Although tragic, the number of lives lost was very low compared to the size of the project and the dangers involved.
27. GGBSVC_180715_241.JPG: A Lasting Monument When asked how long the Golden Gate Bridge would last, Chief Engineer Joseph Strauss replied, "Forever." The Bridge was designed to be strong and durable, but to make it a lasting monument requires continual maintenance and improvements. Since its opening in 1937, the Bridge has had many upgrades and retrofits: * bracing across the bottom of the deck, to make the deck twist less in high winds * a portion of the roadway deck was replaced with a lighter-weight structural layer * all of the 500 vertical lines you see on the bridge, the suspender ropes, were replaced one by one * seismic retrofits have been installed from one end of the Bridge to the other * some of the original riveted-together X-braced struts as seen in the arch portion of the Bridge over Fort Point have been replaced with higher-strength pieces of steel * prevention of rust goes on constantly; the signature International Orange color is always used for re-painting the historic structure to preserve its appearance * motion-measurement sensors have been installed throughout the Bridge, monitoring how it responds to wind, earthquakes, traffic loads, and temperature changes The staff needed to maintain the Bridge includes engineers, ironworkers, electricians, and painters, to name a few. The workforce of the Bridge take great pride in their role in maintaining not only an essential transportation route but also a famous and beloved landmark.
28. GGBSVC_180715_249.JPG: Battery Lancaster Defending the Golden Gate Battery Lancaster, the northernmost of Fort Winfield Scott's coastal defense batteries, was part of a chain of fortifications that spanned the Golden Gate. Battery Lancaster's mission was unique, among the many artillery installations on this bluff. From 1900 through World War I, Lancaster's three guns offered the only artillery coverage from the south for the narrowest part of the harbor entrance. In addition to the gun pit, and the two gun emplacements, Battery Lancaster featured several underground rooms and ammunition magazines. Most of these were buried or destroyed by construction of the Golden Gate Bridge in the early 1930s. However, portions survived and the battery saw service again during World War II. Following the attack on Pearl Harbor, soldiers were sent to defend the Bridge. The commanding officer selected flat ground near the toll plaza for the company's antiaircraft guns and set up his headquarters, and quarters for his soldiers, in what remained of Battery Lancaster. World War II Defenses Under the command of Captain Harry Freeman, World War II troops protected the Golden Gate Bridge with antiaircraft guns and lived in Battery Lancaster, in underground rooms beneath the Bridge toll plaza.
29. GGBSVC_180715_251.JPG: Resisting the Twisting Ever since the modern suspension bridge was invented in the early 1800s, one of the biggest challenges engineers have faced is preventing these flexible structures from moving too much in the wind. A storm on December 1, 1951, caused the Golden Gate Bridge to twist and vibrate enough to cause some minor damage, so the Bridge was retrofitted from 1953 to 1954. The retrofit added new bracing across the bottom, connecting the two steel trusses that support the roadway deck. This change increased the Bridge's twisting, or torsional, stiffness. Original Bridge Deck Shape This is a scale model of a 500-foot (152-meter) length of the original deck structure of the Golden Gate Bridge, without the roadway on top. The trusses on the sides, along with the framing on top that supports the roadway, form an upside-down U-shape. Retrofitted Bridge Deck Shape This model shows the Bridge deck today. The difference from the original design, shown above, is the addition of bottom bracing. The cross section is a closed shape.
30. GGBSVC_180715_257.JPG: Suspension Cable Tension vs. Tower Height Engineers had to balance the advantages and disadvantages of tower height and cable size in the final design of the Golden Gate Bridge. When completed in 1937, the Bridge had the tallest bridge towers in the world. Making them considerably taller to reduce the tension (pulling) force in the cables would have been a more difficult and expensive design alternative.
31. GGBSVC_180715_267.JPG: How the Bridge Spans the Golden Gate l. Deck Trusses Look at the trusses that extend along the length of the Bridge. The weight of the roadway and sidewalk structure, and of the cars, pedestrians, and bicyclists, is supported by the deck trusses. The diagonal struts outline the basic structural unit of a truss, the triangle, which is inherently strong and stiff. However, the deck trusses are not strong enough to span all the way across the Golden Gate. They are held up every 50 feet (15 meters) by vertical steel suspender ropes. 2. Suspender Ropes See the 500 vertical lines (steel suspender ropes) across the Bridge? They are the next step in the "load path", which is the term that describes how the weight of the Bridge, including the weight of traffic, is transferred ultimately to the ground. The deck trusses hand off their load to the ropes, which pull that weight up to the curving main cables. The weight of the deck is suspended from the main cables by these suspender ropes, hence their name. 3. Main Cables When you look at the tops of the two towers of the Bridge, you see where the two cables are supported. All the weight of the roadway and sidewalk deck structure, the traffic, the steel suspender ropes, and the self-weight of the curving main cables, is placed on the tops of the two towers by the cables. 4. Towers What holds up the two main cables? When you wear a backpack, the straps pull the weight up to your shoulders, and then that load must travel a path down your body all the way through your legs to the ground. The poles that hold up a tent, or a tightrope walker at the circus, or a clothesline, must also carry the weight to the ground. In the Bridge, the towers carry all the gravity loads of the entire suspension structure, from one end to the other, down to the ground. 5. Foundations The foundations are the final step in the load path. The forces carried down through the steel towers are resisted by the strength of the concrete foundations, which extend into bedrock. The pulling or tension forces in the cables are resisted by the massive concrete anchorages at both ends of the Bridge, and those anchorages are also embedded in bedrock. The loads of the Bridge flow through the foundations and reach the earth, completing the load path.
32. GGBSVC_180715_275.JPG: Art Deco on a Grand Scale The Golden Gate Bridge is one of the world's largest examples of the Art Deco style. Named for the Exposition Internationale des Arts D�coratifs et Industriels Modernes, held in Paris in 1925, the Art Deco style was used by architect Irving Morrow to add aesthetic touches throughout the Bridge. These include chevron or beveled shapes and an expression of verticality. The chevron design and the angular, stepped brackets on the horizontal struts of the Bridge are nonstructural, added for visual effect. Lights that point down are street lights for Highway 101 traffic crossing the Bridge. The round lights pointing up emphasize the height of the towers at night, an up-lighting technique often used on Art Deco skyscrapers of the 1930s, such as the Empire State Building. The concrete pylons at the ends of the arch portion of the Bridge have a chevron form in both plan and elevation. Their tops are another Art Deco feature: they do not meet the sky as a squared off shape like a flat roof but rather with staggered vertical forms. A hidden Art Deco gem at the Marin (north) side of the Bridge, viewed from Battery Spencer. The concrete at the base of the south tower also received an Art Deco treatment.
33. GGBSVC_180715_277.JPG: Steel, Fog, Salt, Rust, and Paint Only rarely must the Golden Gate Bridge withstand earthquakes or strong wind, but everyday it must fight another threat: corrosion of the steel which creates a byproduct called rust. Steel is an alloy comprised principally of iron along with small amounts of other elements such as carbon or nickel. When steel is exposed to the oxygen in air and to water, the iron changes through a chemical process called corrosion; this change creates rust which erodes the steel making it slightly smaller and weaker than before the corrosion took place. On the Bridge, fortunately, the steel sections were originally over-sized in anticipation of corrosion and other threats. Water vapor evaporating from the ocean is all around the Bridge and often cools and condenses to form fog. Corrosion is sped up by the presence of salt. The sea air around the Bridge not only supplies the water needed for rust -- it is also loaded with millions of tiny particles of salt. In the 1930s the original primer paint on the Bridge was two-thirds (by weight) lead. Lead is a good material for preventing rust, but is harmful to people and the environment. Today different areas of the Bridge are re-painted about every ten to twenty years. Due to environmental concerns, today's primer contains zinc instead of lead. The zinc protects the steel, because zinc corrodes more easily than steel. Zinc serves as a sacrificial metal, so the steel does not rust when zinc is present. On top of that zinc primer is a top coat of paint in the Golden Gate Bridge's signature color called International Orange. Besides International Orange, other color schemes were considered when the Bridge was built. One alternative that was proposed was a striped design to make it more visible to ships and airplanes.
34. GGBSVC_180715_285.JPG: Tall and Strong Tallest Bridge Towers The Golden Gate Bridge not only set the record for longest bridge span when completed in 1937, it also had the tallest towers. Honeycomb Legs – Strong But Light This innovation introduced by the Golden Gate Bridge provided the strength to withstand the tremendous weight transferred to the tops of the towers by the cables, and also to resist horizontal loads due to wind and earthquakes. Over a Million Rivets Each tower has over a million rivets. A red-hot rivet with a round head on one end was inserted through holes to join pieces of steel. Then while the round-headed end was held securely, a riveter with a power tool hammered ("bucked") the plain end into another mushroom-shaped head, clamping the pieces together.
35. GGBSVC_180715_290.JPG: Types of Bridges Suspension bridges are the longest-spanning bridges in the world. Prior to the record set by the Golden Gate Bridge in 1937, 4,200 ft (1,280 m), the longest-spanning bridge in the world was the George Washington Bridge, with a span of 3,500 ft (1,067 m). Today, the longest-spanning bridge in the world is the Akashi Kaikyo Bridge in Japan, with a span of 6,352 ft (1,991 m). Arches were often used in ancient times to form bridges. Arches carry load primarily in compression (resisting pushing forces.) They can be made out of masonry (stones or bricks) because those materials are strong in compression. Each stone or brick pushes on its neighbor. Masonry is also durable, and most locations have a natural supply of stone that can be cut into shapes or clay that can be hardened with fire into bricks. The Romans built many arch bridges, such as the multi-level Pont du Gard that can be visited in France. That bridge served as an aqueduct to carry water over a river valley. Water ran in a trough at the top level of the bridge. Cable-stayed bridges have straight cables extending from towers to hold up the roadway deck. As those cables (stays) pull up on the deck, they also pull toward the mast, and thus the roadway deck structure must be strong enough to resist a large compressive force. Crossing the Millau Viaduct in France, cars drive 1,132 ft (343 m) above the valley below. The straight members that make up a truss are struts or "sticks" of steel in modern bridges. The struts form triangles, which are inherently rigid. Truss bridges carry weight effi�ciently because each of their straight members is either pulled (in tension) or pushed (in compression). The tension or compression flows straight through the length of each member, without causing it to bend or flex. When the Firth of Forth Railroad Bridge was completed in Scotland in 1890, it was the longest-spanning bridge in the world (1,710 ft, 521 m) and one of the first to be made of steel rather than iron. Beam bridges were invented when people first placed logs over streams and walked across. Most short-span bridges crossing roads or highways are supported by steel or reinforced concrete beams. If the beam only rests on supports at both ends, it tends to sag as it bends or flexes. This stretches the material (makes it feel tension forces) along the length of the beam's lower edge. Concrete is good at resisting compression (pushing) but is weak in tension. A concrete beam resting on supports at both ends, as shown here, needs steel reinforcing bars or steel cables embedded along the beam's length near its lower edge to resist tension.
36. GGBSVC_180715_297.JPG: Facts & Figures About the Bridge Quick Facts on the Golden Gate Bridge Period of construction: Just over four years. Construction commenced on January 5, 1933 and the Bridge was open to vehicular traffic on May 29, 1937. Cost: $35 million dollars in the 1930's, approximately $1.5 billion in year 2016 dollars. The name Golden Gate does not refer to the Bridge's color, it is the name of the entrance to the San Francisco Bay from the Pacific Ocean, which is called the Golden Gate Strait. How big is the Golden Gate Bridge? When constructed in 1937, it set the world record for the longest bridge span, the distance between supports (4,200 ft, 1,280 m) and also the tallest towers. Height of tower above water: 746 ft = 227 m Height of tower above roadway: 500 ft = 152 m Length of suspension span including main span and side spans: 1.2 miles = 6,450 ft = 1,966 m Total length of Bridge including approaches from abutment to abutment: 1.7 miles = 8,981 ft = 2,737 m. The width of Bridge: 90 ft = 27 m The weight of the Bridge, not counting the concrete anchorages, is 840 million pounds (382 million kg) - heavier than the Empire State Building. How big is the main cable? The diameter of one main cable: 36 3/8 in. = 0.92 m Length of one main cable: 7,650 ft = 2,332 m Each cable is composed of 27,572 wires. If the wires were one continuous length, they could wrap around the earth over three times. Shown above is a diagram of how the 27,572 wires in a cable were grouped together and then tightly compressed into their final form by a hydraulic press. Why is it called the Golden Gate Bridge, Highway and Transportation District? Traffic jams are rare on the Bridge because the Bridge District added ferry (1970) and bus (1972) transit service. Annually, 40 million vehicles cross the Bridge; two-and-one-half million passengers are transported by the ferries; and over 6 million passengers ride the buses. For more interesting facts and figures about the Golden Gate Bridge: www.goldengatebridge.org/research
AAA "Gem": AAA considers this location to be a "must see" point of interest. To see pictures of other areas that AAA considers to be Gems, click here.
Bigger photos? To save server space, the full-sized versions of these images have either not been loaded to the server or have been removed from the server. (Only some pages are loaded with full-sized images and those usually get removed after three months.) I still have them though. If you want me to email them to you, please send an email to guthrie.bruce@gmail.com and I can email them to you, or, depending on the number of images, just repost the page again will the full-sized images.
2018 photos: Overnight trips this year: (February) Greenville, NC for a Civil War Trust conference,, (May/June) Newport News, VA for another CWT conference, (July) my 13th consecutive trip to San Diego Comic-Con (including sites in Reno, Sacramento, San Francisco, and Los Angeles), (August twice, October) three trips to New York City (including New York Comic-Con), and (September) Chicago, IL for my CWT swansong event. Equipment this year: I continued to use my Fuji XS-1 cameras but, depending on the event, I also used a Nikon D7000. Number of photos taken this year: about 535,000.
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Photo Contact: [Email Bruce Guthrie].