Development Of The Golden Gate Bridge Outdoor Exhibition

THE GOLDEN GATE BRIDGE AS AN INFORMAL SCIENCE EDUCATION RESOURCE

Copyright © 2016 Golden Gate Bridge, Highway and Transportation District

Funding for this project provided by the National Science Foundation, Division of Research on Learning in Formal and Informal Settings (award DRL-0840185), awarded to the Golden Gate Bridge, Highway and Transportation District.

Denis Mulligan, Principal Investigator of the Project; General Manager, Golden Gate Bridge, Highway and Transportation District

Robert Reitherman, Project Manager, Consortium of Universities for Research in Earthquake Engineering (CUREE)

Exhibit booklet research and layout: Reed Helgens and Darryl Wong, CUREE

Prepress production: George Mattingly Design

TABLE OF CONTENTS

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

PUBLIC WORKS FOR PUBLIC LEARNING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

EXHIBIT DEVELOPMENT OVERVIEW EVALUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

THE INTERNATIONAL CONFERENCE: PUBLIC WORKS FOR PUBLIC LEARNING (2012) . . . . . . . . . . 13

STUDENT INVOLVEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

ORIGINAL CONCEPT AND MODIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

AN UNEXPECTED VISITOR EXPERIENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

LIST OF EXHIBITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

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This project extends beyond the usual venue of the science center to provide Informal Science Education (ISE) experiences for the over 10 million visitors who are annually drawn to the Golden Gate Bridge. Visitors already have an exciting experience looking at the Bridge and its spectacular location at the juncture of the Pacific Ocean and San Francisco Bay. Through the development of outdoor exhibits, the project builds on this positive experience by enabling visitors to acquire Science, Technology, Engineering, and Mathematics (STEM) insights concerning the world’s most famous bridge. Exhibits are designed to surprise our visitors with how enjoyably they can explore STEM topics: They come as sightseers, they leave with a positive ISE experience that piques their curiosities.

A secondary audience of the project has been the operators of similar infrastructure facilities and informal science education professionals, who were invited to attend an international conference, Public Works for Public Learning, around the 75th Anniversary of the Bridge in 2012.

Introduction

Evaluation consultants were retained to measure usage of the exhibits, and resulting depth of understanding, which, given the large number of visitors, was accomplished on a stratified sampling basis.

The NSF award was made to the Golden Gate Bridge, Highway and Transportation District. Project management and lead design were performed by the Consortium of Universities for Research in Earthquake Engineering. Other exhibit designers were Princeton University, the Exploratorium, and West Wind Laboratory. EHDD Architects provided site planning services.

INTRODUCTION

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PUBLIC WORKS FOR PUBLIC LEARNING

The conference on “Public Works for Public Learning” held in San Francisco in June 2012, had as its keynote speaker, Dr. G. Wayne Clough, Secretary of the Smithsonian Institution.

Dr. Clough shared his unique perspective as a civil engineer, educator, and Secretary of the Smithsonian Institution. He gave his insight on the power of public works projects like the Golden Gate Bridge to teach important lessons about history, engineering, culture, and geology.

In his presentation titled “If you Build It, They Will Come,” he explained how public works projects are historic milestones representing some of humankind’s greatest achievements. Engineering marvels from Machu Picchu to the Panama Canal have benefited societies for centuries, informed architects, designers, and engineers alike, and enriched everyone’s understanding of the world.

Introduction

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OVERVIEW

Over thirty exhibits engage the visitors and explain the engineering and history of the Bridge. Approximately ten million visitors per year come to the Bridge to walk around it, on it, or view it from bicycles. Several design principles are relied upon to make the exhibits a fun learning experience. Illustrations, simple analogies, and hands-on interactive features, rather than just text and numbers, are used to present the many mathematical relationships involved in engineering a suspension bridge.

Visitors are enticed to learn through out-of-the-classroom, voluntary learning (informal learning). Informal learning is different than the instruction that occurs in the classroom (formal learning), as what is learned is experiential and self-directed. Informal learning invites a visitor to ponder an interesting question, and then learn about it. Because the Golden Gate Bridge itself is the “headliner” exhibit, it is important to connect the immediacy of the experience a person has at the site with the content of the exhibits.

Exhibit illustration by Aaron Neighbour, CUREE

How does one get across the interesting concept that as the wind speed doubles, the wind pressure a structure must resist more than doubles–it quadruples? Instead of just saying “wind pressure varies as the square of the velocity,” a one-foot-square plate with a handprint on it invites the visitor to push and see how much force is felt to make a speedometer read out higher and higher wind speeds.

EXHIBIT DEVELOPMENT

Exhibit Development : Overview

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Exhibition On The Web

QR (quick response) codes were added to each exhibit to provide the visitor with direct access to the Golden Gate Bridge’s website on the exhibition. Each exhibit’s text is translated into nine languages, plus English, with additional information on the individual exhibits provided at: http://goldengate.org/exhibits/.

Prior to designing some of the exhibits for the project, Exploratorium designers visited the lab of Stanford University civil engineering professor Sarah Billington to explore structural engineering principles with her instrumented scale-model of the Golden Gate Bridge.

Exhibit Development : Evaluation

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EVALUATION

Research was conducted, prototypes made and remade, drafts were discussed and critiqued, and only then were the final exhibits constructed.

Front-end evaluation was conducted by Inverness Research at the beginning of the project, when goals and initial design were being considered. Front-end evaluation collected input from potential visitors to find out what kind of information they already know, what visitors would like to know, and explored how exhibits could best present the interpretive information being provided.

Summative Evaluation was conducted by David Heil & Associates after final installation, when the exhibits could be evaluated and final adjustments could be made.

Placement of the exhibits throughout the south visitor area of the Golden Gate Bridge was another consideration, as some of the exhibits operated best in a windy location, or made the most impact within view of the Bridge. It was necessary to work within the restrictions set by the National Park Service, which regulates the land around the visitor area, for final placement of the exhibits.

[Shown right (top to bottom)] • An exhibit by The Exploratorium that demonstrates how the height of the tower impacts the amount of tension in the main cable is first sketched out. • A prototype is built and public feedback is gathered. A suggestion to make the posts resemble the Bridge towers is illustrated using paper templates. • The final design, with towers resembling the actual towers of the Bridge.

Exhibit Development : Evaluation

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To broaden the outreach of the exhibition, a tactile exhibit was developed to be accessible to visitors who are blind or have impaired vision. Designed with Braille lettering, it includes a raised relief of the layout of the bridge design and a model of a Bridge tower the visitor is able to touch to gain a concept of the overall shape of the Bridge and of one of the towers.

A nonprofit organization, The Lighthouse for the Blind and Visually Impaired, tested a plastic model for accuracy of the Braille text and effectiveness of the overall design. A suggestion that was incorporated was to be sure the model width did not extend past the average reach of a visitor so that both hands could reach and touch the entire depiction of the Bridge. The final model was cast in bronze.

Exhibit Development : Evaluation

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The area around each exhibit and the height of the tabletop displays were measured to be accessible to visitors in wheelchairs. Other details included the rounding of sharp corners, using a font large enough to be easily legible, and ensuring the base of each exhibit did not block wheelchairs.

A special section for teachers and students may be found on the exhibition website where additional content is posted and sorted into material appropriate for students in kindergarten to fifth grade, students in sixth through eighth grade, and students in high school and college level, using the categorization of the Next Generation Science Standards.

The website link is accessible on site by a QR code posted at each exhibit. Links to videos related to the construction and maintenance of the Bridge have also been added to the website.

Exhibit Development : Evaluation

Suggested display heights for viewing based on various heights of visitors.

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THE INTERNATIONAL CONFERENCE: PUBLIC WORKS FOR PUBLIC LEARNING (2012)

[Shown left] Students and speakers at the Conference, on the steps of the Hyatt Regency Hotel in San Francisco.

[Shown above] Photos from the Golden Gate Bridge International Conference.

A two-day conference titled Public Works for Public Learning was the forum to exchange innovative ideas about educational programs that positively impact visitors at a wide range of types and sizes of public works facilities. The nation’s infrastructure is a very underused informal learning resource, and bringing the extensive public works community within the fold of Informal Science Education can lead to greater opportunities to bring STEM concepts to a wider audience.

The conference brought together experts and individuals from both the arena of civil engineering works and the informal science education community to further a common goal—communicating through a variety of means, including exhibits, the importance of our public works, and exploiting the learning potential of these ubiquitous features of our environment.

Presenters included representatives of “celebrity” civil engineering facilities, who made presentations on their extensive and varied interactions with the public: Hoover Dam, Eiffel Tower, Los Angeles Department of Water and Power, Sydney Harbour Bridge, and the Panama Canal.

International Conference

12 | 14 | International Conference

The conference also featured small-scale public works like the Arizona Falls Waterworks facility, a small hydroelectric plant that was converted into a public gathering place and museum. To reach other public works departments throughout the United States, the American Public Works Association (APWA), was a partner in the project.

Conference planning began in early 2011, with invitations extended to the both the informal science education community and the APWA. The APWA is a not-for-profit, professional association of public works agencies with over 25,000 members across the United States. Project team members promoted the conference by speaking at APWA meetings and publishing articles about the project in the APWA’s monthly magazine The Reporter.

The APWA annually mounts an extensive public outreach effort centered on National Public Works Week. In 2012, the artwork used to represent National Public Works Week was a watercolor painting of the Golden Gate Bridge, a nod to the Bridge celebrating its 75th anniversary.

The conference provided APWA members who attended with ready-to-use practical guidance on how a local public works department or utility can develop effective exhibits to allow the public to understand the STEM principles underlying their infrastructure. APWA offered a course developed by the project to its membership on “How to Develop Effective Public Works Exhibits” through its ongoing training program that grants continuing education units (CEUs) to its members.

[Shown left] The Arizona Falls Waterworks Facility in Phoenix, AZ, a functioning hydroelectric plant with public areas for science shows and art festivals.

[Top to bottom] Special guest speakers included Nicolas Lefebvre (The Eiffel Tower), Javier Pinzon Pascal (Panama Canal Authority), and David Lawry and Larry Lux, part of the APWA panel discussion.

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Exhibitions are typically intended to entertain and arouse curiosity, thus promoting learning for the visitor. What is not commonly known is that there are also desirable effects on the people designing the exhibition, especially if those people are students. There are teaching opportunities that include the following: (1) considering constructibility aspects of structural design through model building; (2) communicating by drawing; (3) developing a clear vision by learning to simplify ideas into their most fundamental parts; and (4) once that clear vision is established, communicating ideas to the general public. The communication is made through models, descriptive panels, and a website explaining the theme of the exhibition in layman’s terms.

For students of structural engineering, these exhibition designs complemented their education by teaching them tools that are not taught in a typical engineering education, yet are fundamental to their careers. Five students involved with the project wrote their graduate theses based on their research conducted on their exhibits, a total of fifteen undergraduate and graduate students at Princeton University participated in the project.

Dr. Maria Garlock, Associate Professor at Princeton University in the Department of Civil and Environmental Engineering, teaches several courses related to structural engineering and does research related to improved design for the response of structures to earthquakes and large fires. In addition, she studies the best examples of structural designs of the present and past (i.e. “structural art”) and uses this to inspire her research and teaching.

Three of the Princeton University engineering students who worked on the project; left to right: Nathan Brown, Michelle Lau, and Stephanie Chen.

[Shown on opposite page] Sylvester Black (left), former Princeton civil engineering student and now a practicing structural engineer and designer of the project’s large (86-foot-long) scale model of the Bridge, shown with a prototype of some key connections. Jorge Lee (center), primary Bridge District engineer overseeing the exhibits, and Bridge District General Manager Denis Mulligan, observe Black’s explanation of the construction process.

Denis Mulligan, the NSF grant’s Principal Investigator and General Manager of the Bridge District in a design review meeting with Princeton University students William Plunkett (left) and Gavin Daly.

STUDENT INVOLVEMENT

Student Involvement

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16 | 18 | Original Concept and Modifications

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ORIGINAL CONCEPT AND MODIFICATIONS

[shown left] Conceptual view of the original plan for the exhibition gallery with the cut-through, looking north toward the Bridge.

The planned exhibition included a variety of models, displays, and interactive exhibits that would provide visitors ways to learn about the engineering, construction, maintenance, aesthetics, and history of the Golden Gate Bridge. These exhibits would be grouped within an outdoor gallery area that would include an eighty-foot-wide mural and feature a 1:80 scale model of the Bridge 86 feet long made out of stainless steel. The bridge model would serve as a “table of contents” for the surrounding exhibits, providing a point of reference, and would be mounted on columns on which the geological substrate of the bay bottom would be represented.

To create such a display, a remodel of the area known as Battery Lancaster was needed. Battery Lancaster was one of several man-made areas built up out of dirt and concrete in the 1890s to house and protect a group, or battery, of large cannons installed by the U.S. War department to protect the Golden Gate Strait. Never fired in time of war, the cannons were removed and only the open gun pit remains. The plan was to create a cut-through of the battery wall to provide both a view of the Bridge and a flow-through of foot traffic that would lead directly to the Bridge.

The land on which the Golden Gate Bridge, Highway and Transportation District toll plaza and administrative offices reside was originally owned by the U.S. War Department and was later transferred to the National Park Service. Any modification to the area requires a permit from the National Park Service. Permission for a permit was requested, denied, then modified and resubmitted multiple times. The permit is still pending.

During the approval process, some of the exhibits were installed on an interim basis in time for the 75th anniversary celebration of the Golden Gate Bridge. In preparation of the upcoming celebration, the Bridge’s south visitor area was simultaneously being remodeled by the Golden Gate National Parks Conservancy, a nonprofit organization that raised funds to improve the visitor’s experience at the Bridge’s south visitor area. A visitor pavilion was built, a new plaza was created, bike paths, hiking trails, signs, and benches were added. Space was at a premium and it was not possible to group the exhibits together.

Original Concept and Modifications

20 | Original Concept and Modifications

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The exhibits that were ready were installed in various locations around the remodeled visitor area. Placement of each exhibit had to take into consideration the wind and weather, foot traffic, and visual access to the Bridge. For example, exhibits which discussed the seismic retrofitting of the Bridge needed to be placed where the visitor could see the actual retrofits to make an immediate association. Remoteness of some areas became another consideration, as vandalism became an issue. Exhibits placed in outlying areas were subject to breakage and graffiti and needed to be replaced and relocated.

Instead of an eighty-foot mural on the history of the construction of the Golden Gate Bridge, a 10-ft by 34-ft banner of the Bridge was produced and hung inside the battery, accompanied by nine tabletop mounted panels that touch on key historical developments of the Bridge. Several planned exhibits were never produced due to lack of space for proper installation.

By the time the NSF project ended in August 2016, a National Park Service permit granting permission to modify the Lancaster Battery area to create the needed gallery space was not issued, and the original design of the exhibition was not realized.

Conceptual view of the original plan for the exhibition gallery looking south.

Original Concept and Modifications

Mural design incorporating illustrations, original construction drawing, and tabletop displays explaining the design and construction of the Bridge.

[Shown left] The history mural planned for permanent installation on a new retaining wall was modified into a temporary banner hung inside Battery Lancaster above nine tabletop displays. Because the National Park Service considered the 1890s concrete slab to be historic, tabletops could not be bolted down and had to be stabilized with weights.

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AN UNEXPECTED VISITOR EXPERIENCE

Besides being educational, several of the exhibits provided the unexpected benefit of being a photo opportunity. Designers of these exhibits were surprised to see how visitors chose to interact with the exhibits in ways not originally considered. The model designed to show how a suspension bridge deck moves is frequently featured in photos with guests entwined around the model posing for pictures with their arms and heads inserted into the model’s frame as if they’re embracing the Golden Gate Bridge. Some guests see the interactive exhibits as a test of personal strength, pulling and pushing on handles as hard as they possibly can, oblivious to the experience the exhibit originally was intended to display. Exhibits had to be designed to be rugged to withstand heavy use, or at the very least, easy to repair.

An animated mural created by LIFETILES uses a system of glass tiles embedded with layers of images to display different phases of the construction of the Golden Gate Bridge as a viewer moves past the mural. The visitor’s changing angle of view reveals a different layer of images. The visitor sees phases of the Bridge’s construction from an open Golden Gate Strait, to the appearance of the towers and the cables, and finally the addition of the deck, ending with the completed Bridge. Visitors frequently stop to have their photos taken, adjusting their camera angle to take a photo of every changing phase.

An Unexpected Visitor Experience

[Shown at left] Designed by Rufus Butler Seder, this LIFETILES animated mural shows the construction sequence of the Bridge. As a visitor walks past, one’s changing angle of view suddenly changes the image one sees. The numerous “photo op” snapshots visitors take become publicity for the exhibition as those photos are shared with friends.

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Facts & Figures About the Bridge

Answers some of the most frequently asked questions about the Golden Gate Bridge, such as: “If all the wires in the main cables were one continuous length, how far would they reach?” or “What is the span of the Bridge and its total length?”

Braille / Tactile Model of the Bridge

A bronze tactile-readable tabletop model of the Bridge with Braille captions and an 18-inch high replica of a tower depicts the structure and shows why the towers were placed so far apart. Putting them closer together would have meant building foundations in deep water, and underwater construction was one of the most difficult tasks in the project.

LOCATED NEAR THE GIFT STORE

LIFETILES: Animation of the Construction of the Bridge

Using the technology developed by Rufus Butler Seder, this glass tile mural animates as the visitor walks past it, displaying first the Golden Gate before the Bridge was built, then the stages of construction (foundations and towers, main cables, vertical suspender cables, deck).

Cross-section of a Main Cable: an original Golden Gate Bridge exhibit

This classic exhibit has been at the Bridge for decades, touched and photographed by millions of visitors. The cross-section shows how each cable is composed of 27,572 individual steel wires.

LIST OF EXHIBITS

LOCATED AT THE ENTRANCE TO THE BATTERY

List of Exhibits

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Tall and Strong - The Bridge Towers (includes “What is a Rivet?”)

The entire weight of the bridge deck, with vehicles, pedestrians, bikes, etc., is supported by the two towers. Many people assume the towers are solid steel; they are actually made up of connected cells and provide strength with a minimum of materials. This exhibit also explains how rivets were used to permanently clamp the pieces of steel together.

LOCATED AT THE ENTRANCE TO THE BATTERY (continued)

Fog, Steel, Salt, Rust, and Paint

The International Orange color of the Golden Gate Bridge is very much part of its landmark signature. The paint also plays a critical role in protecting the Bridge in the wet and salty environment of the California coastline. A painted and unpainted steel sample on this exhibit illustrate the effects of corrosion.

Art Deco on a Grand Scale

The Golden Gate Bridge is known for its architectural detailing, designed in the style of Art Deco. The design can be found in the shape of the towers, the deck lights, in the strut covers connecting the two tower legs, and in the chevron design used throughout the structure.

How the Bridge Spans the Golden Gate

An illustrated guide to the load path of the Bridge – how the weight of the road deck and its traffic is carried up to the main cables by suspender ropes, then transferred to the tops of the towers and down to the earth, with the ends of the main cables firmly anchored in concrete to resist the tension (pulling) forces.

There is also a flip door that graphically communicates these points in a cartoon illustration.

Types of Bridges

A visual description of the major kinds of bridges: suspension, arch, cable-stayed, truss, and beam. The longest-spanning bridges in the world, like the Golden Gate Bridge, are suspension bridges.

List of Exhibits

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Engineering the Design

A great deal of planning, testing, and calculations went into the final design of the Golden Gate Bridge.

Bridging the Gate - The Beginning

The idea of building the Bridge had been discussed for many years, and it took many more years to overcome much adversity to establish the Bridge District to oversee the building of the Bridge and to issue bonds to cover the cost of construction; Chief Engineer Joseph Strauss is credited with leading the effort to win official approval and public support.

A Bathtub for the South Tower

Visitors cannot see the massive concrete foundation that extends to the sea floor. A ring, or fender, was originally constructed to allow for the pouring of concrete for the tower base. The fender walls were left in place to protect the South Tower from impact by wayward ships.

Working Under Water

The south tower was located offshore in water almost 100 ft (30 m) deep. Workers with diving helmets and air hoses descended to the ocean floor to prepare the surface for the concrete foundation. The cold, murky water and strong currents made the work very difficult. The divers could only work when the current diminished as the tide slackened.

LOCATED IN THE BATTERY

THE HISTORY OF THE DESIGN AND CONSTRUCTION OF THE BRIDGE

List of Exhibits

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World’s Tallest Bridge Towers

To build the world’s tallest towers special machinery was required, such as climbing derricks, and workers without a fear of heights. Catwalks, made out of wood planks and rope, were used to travel to the construction work, hundreds of feet above the water.

Spinning the Main Cables

The two main cables were fabricated and installed by the company established by John A. Roebling in the 1800s, using a “spinning” process he invented. Each main cable is made up of thousands of individual wires about as thick as a pencil. Although each cable is made up of 27,572 wires, the work was completed in only six months.

Hanging the Roadway Deck

After the towers had been completed, and the main cables were in place, 250 pairs of steel suspender ropes were installed. From these suspender ropes were hung the sections of the roadway deck that were incrementally installed in order to balance the weight on the main cables during construction.

LOCATED IN THE BATTERY (continued)

All in a Day’s Work

In the depth of the Depression, construction jobs on the Bridge were highly sought after. Fog, wind, and cold temperatures made the work difficult. Safety measures were enforced; however, even though a safety net was installed during construction, 11 men fell to their deaths when a piece of scaffolding came loose and tore through the net.

A Lasting Monument

Continual maintenance to guard against rust is required to sustain the Bridge. To keep up with the increase of engineering knowledge that has occurred since the Bridge was finished in 1937, retrofits have been implemented to protect it from earthquakes and high winds.

List of Exhibits

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Resisting The Twisting

Completed in 1937, the design of the Golden Gate Bridge did not benefit from knowledge about the collapse of the Tacoma Narrows Bridge in 1940, which twisted itself to collapse in a moderate breeze. The Golden Gate Bridge was retrofitted in 1954 to make the deck more resistant to twisting, which is felt by the visitor with this hands-on exhibit of small models of pre- and post-retrofit bridge decks.

Suspension Cable Tension vs. Tower Height

Engineers must calculate trade-offs and consider multiple design factors. Taller towers would have reduced the tension force in the main cables. But taller towers also mean more structural and construction problems and more cost. Models of different height towers allow the visitor to experience the difference in cable tension.

Battery Lancaster

At one time large cannons were installed behind walls of concrete and earth to protect the Golden Gate strait. The large metal “doorknockers” in the concrete walled gun pit were used to maneuver the cannon in that area, using ropes or chains. Never fired in battle, the cannon was soon removed, but the rings and battery walls remain.

LOCATED IN THE BATTERY (continued)

List of Exhibits

Wind Speed and Wind Pressure

The Golden Gate is a very breezy place, because it is the only gap in the coast range for hundreds of miles. Cool, dense, high pressure air over the cold ocean pushes its way into the Bay. Wind force varies as the square of the velocity, a fact the visitor can intuitively sense by pushing on this exhibit.

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LOCATED UNDER THE BRIDGE ON WEST SIDE

Seismic Isolation

Approach spans to the suspension bridge have been retrofitted with seismic isolators. In an earthquake, the isolator deforms sideways in a “squishy” manner, resulting in the structure above the isolators experiencing a less violent level of shaking.

Seismic Retrofits & Historic Preservation

The original bracing members (struts) in the arch structure and adjacent approach spans were made of hundreds of small pieces of steel riveted together. A seismic retrofit has replaced many of these lattice truss struts with modern one-piece steel tubes—but with triangles carefully laser-cut out so the replacement struts look like the originals. The exhibit explains how U. C. Berkeley tested a replica strut in the laboratory to measure its strength.

Bridge Deck Aerodynamics

Wind blowing across (transversely to) the deck of a suspension bridge can make it begin to twist – a very undesirable type of structural response. This exhibit has two scale-model bridge decks next to each other. One model is aerodynamically more stable in a breeze; the other model noticeably twists. Excessive twisting can result in self-destruction as shown in photos of the Tacoma Narrows Bridge.

Plate Tectonics

Earth’s crust is divided into about a dozen large areas or plates, and at the boundaries of these plates, where they rub and push against each other, strain is built up that is released by earthquakes. Offshore of the Bridge to the west is the San Andreas Fault, the fault that slipped in 1906 and caused the San Francisco Earthquake. That fault is the dividing line between the North American Plate where the Bridge is sited and the Pacific Plate.

Ships of the Golden Gate

The Golden Gate is one of the best places in the world to watch ships. This exhibit illustrates some of the basic kinds of vessels one sees going in or out of the Bay.

List of Exhibits

Examples of Bridge Cross Sections

Tacoma Narrows Bridge

Modern aerodynamically designed bridge

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LOCATED ON GGBHTD FERRY BOATS

How the Bridge Vibrates

The Bridge has many modes of vibration, or ways in which it can move in response to wind or earthquakes. This mechanical hands-on exhibit lets visitors “excite” (shake) the model in varying ways to see how it responds.

When It’s Foggy

When it’s foggy, visitors may not be able to see the Bridge, but they get to hear the foghorns. The speed of sound is experienced by the visitor by comparing arrival times of foghorn sounds through the air versus calling a phone installed near the foghorn on the Bridge to hear the sound almost instantly.

Fort Point Arch

To preserve a historic brick building called Fort Point, an arch was built to span over it. Inverting an arch makes it look like the sagging main cables. An arch is in compression while the suspension bridge cables are in tension.

What Suspends a Suspension Bridge?

A single suspender rope is strong enough to hold up one of the Bridge District’s ferry vessels (one-half million pounds).

Bridge Deck Deflection

Suspension bridges are flexible structures. The Bridge was designed to accommodate swaying in strong winds. This exhibit shows the visitor how far the roadway deck is designed to move sideways.

27ft 8 in. (8.4 m)

27ft 8 in. (8.4 m)

LOCATED ON UPPER LEVEL NEAR THE FLAGPOLE

List of Exhibits

ACKNOWLEDGEMENTSEXHIBITS PROJECT TEAM

• Consortium of Universities for Research in Earthquake Engineering (CUREE), Richmond, California. - Bob Reitherman, lead designer and project manager- Reed Helgens, project administrator and historical research- Darryl Wong, web content and graphic design

• Professor Maria Garlock, Princeton University• Rufus Butler Seder, Eye Think, Inc., (LIFETILES)• The Exploratorium, San Francisco, California: David Fleming, Steve Gennrich, Shawn Lani• Jon Raggett, West Wind Laboratory, Inc., Monterey California• Inverness Research, Inverness, California, and David Heil & Associates, Portland, Oregon

The contributions of recommendations of the Advisors to the project are gratefully acknowledged. • Professor Thalia Anagnos, San Jose State University• Jill Andrews, Education and Outreach Consultant • Cathy Frankel, Director of Exhibitions, National Building Museum • Alan Friedman, The Museum Group • Chris Gallagher, Manager, San Francisco Bay Model Visitor Center • Roy Griffiths, Vice-President, Exhibits and Planning, North Carolina Museum of Life & Science • Howard Levitt, Director of Communications and Partnerships, Golden Gate National Recreation Area, National Park Service • Lawrence Lux, The American Public Works Association • Joyce Ma, The Exploratorium • Professor Henry Petroski, Duke University • Professor Stephen Ressler, U.S. Military Academy • Carol Willis, Director, The Skyscraper Museum

Special acknowledgment for the contributions of Denis Mulligan, Jorge Lee and the Golden Gate Bridge, Highway and Transportation District staff for their valuable assistance in the development and installation of these exhibits.

DisclaimerThis material is based upon work supported by the National Science Foundation under award number DRL 0840185. Any opinions, findings, conclusions or recommendations expressed in the materials provided are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

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