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THE GOLDEN GATE BRIDGE AS A PUBLIC LEARNING RESOURCE

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The Golden Gate Bridge, Highway and Transportation District is the recipient of a $3 million grant from the National Science Foundation to establish a permanent outdoor exhibition in the south visitor area at the San Francisco end of the Bridge. The Consortium of Universities for Research in Earthquake Engineering, CUREE, which has developed engineering exhibits for the public in the past, serves as the lead exhibit designer and overall project manager. The exhibits explain the engineering, construction, and history of the Bridge, providing the public opportunities to learn about science, technology, engineering, and mathematics. Denis Mulligan, the General Manager of the Bridge District, is the Project’s Principal Investigator.

This material is based upon work supported by the National Science Foundation (NSF) under Grant No. 0840185 through the Division of Research on Learning in Formal and Informal Settings (DRL). Any opinions, findings, and conclusions or recommendations expressed

in this material are those of the authors and do not necessarily reflect the views of the NSF.

CUREE

Produced by the Consortium of Universities for Research in Earthquake Engineering (CUREE), Richmond, California, for the Golden Gate Bridge, Highway and Transportation District.

© Golden Gate Bridge, Highway and Transportation District 2013

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“The Golden Gate Bridge project, through a number of innovative strategies, clearly is advancing the public’s

awareness and understanding of science and engineering.

The Bridge is an international icon, visited by millions, and now with NSF funding, the south side visitor area has come

alive with interactive educational exhibits.

With continued development, the project is wonderfully positioned to be a model for similar efforts around

the country that seek to use public works facilities as environments for education.”

- Al DeSena, Ph.D.Program Director

Advancing Informal STEM Learning(Science Technology Engineering Mathematics)

NSF Division of Research on Learning in Formal and Informal Settings

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OUTDOOR EXHIBITION SITING

An innovative remodeling of a prime location near the visitor parking lot is being evaluated to create a large, permanent outdoor gallery for the exhibits. In that space, the centerpiece of the various exhibits will be a 1:80 precise model of the Bridge, over 80 feet long, fabricated out of stainless steel. Professor Maria Garlock of the Princeton University Department of Civil and Environmental Engineering has designed the model, along with several of her students who have written undergraduate and master’s theses on their design work to make a realistically scaled model that is a beautiful structure in its own right. Sylvester Black, who began work as a Princeton student and is now a practicing structural engineer with Robert Silman Associates in New York City, is the chief designer of the model.

Figure 1 - One of the concepts under consideration for the ultimate exhibition area looking north toward the Bridge.

5EHDD Architecture, San Francisco, conducted the site planning for the Outdoor Exhibition.

Keyed to the parts of that large model are satellite exhibits around it explaining individual features of the Golden Gate Bridge. The large model and individual kiosk-size exhibits will be in view at the same time the visitor gazes at the beautiful scene of the actual Bridge. The remodeling is pending a permit from the federal regulatory agency of the area, the National Park Service. Currently, many of the smaller exhibits are installed in interim locations in the visitor area.

Figure 2 - Planned exhibition area looking south.

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THE EXHIBITS

Over twenty exhibits engage the visitors and explain the engineering and history of the Bridge. Approximately nine 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. For example, 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.

Visitors are enticed to learn about science, technology, engineering, and mathematics -- what the National Science Foundation calls STEM -- 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.

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Other considerations that had to be taken into account in the design of the Golden Gate Bridge exhibits centered around the characteristics of the visitors. Because of the large number of foreign visitors, and because smart phones have become so ubiquitous, the need to translate display text and make it web-accessible was necessary. Accessibility for people with any of several disabilities was a basic requirement, as was durability to withstand the rigors of an environment with salty air from the nearby ocean, and to withstand the even more rigorous treatment of rough usage and vandalism.

Each of the exhibits is described in the following pages with a brief listing of the learning goal for each.

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TACTILE EXHIBIT WITH BRAILLE

Not everyone can see: blind people need exhibits too. Through the sense of touch, this exhibit, cast in bronze, explains to both the visually impaired and sighted visitor the reason the towers were placed so far apart, creating the need for the longest span bridge in the world. Through touch the visitor can appreciate how the seafloor of the Golden Gate gets much steeper and deeper farther from the shores, leading to a better understanding of the associated design and construction challenges.

Tower design by Tara Weigand, Princeton University and LightHouse for the Blind; fabrication by Cinnabar California

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BRIDGE TOWERS

The towers of a suspension bridge carry all of the weight of the deck and the traffic carried by the deck. Millions of rivets were used to join pieces of steel together. A red-hot rivet, was inserted through holes in the pieces of steel to be connected, then the straight end was pounded into a round head -- like a blacksmith forging and shaping hot metal by hammering it. As the metal rivet cooled, it contracted, pulling the plates of steel tightly together.

Design by Bob Reitherman, CUREE; fabrication by Robert Cerney

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WIND SPEED AND WIND FORCE

The Bridge has to push back against the force of the wind to remain stable. As wind speed increases, its force greatly increases: double the wind speed from 30 to 60 mph and the force needed by a structure (or a person standing up) to push back against that wind quadruples.

Design by Aaron Neighbour, CUREE; fabrication by Monterey Industries

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LIFETILESA unique technique using glass tiles creates murals that animate without any moving parts or electricity. As a visitor walks by the LIFETILES mural, the scene of the Golden Gate changes from 1933, prior to construction of the Bridge, through several construction phases to its completion in 1937.

Design and fabrication by Rufus Butler Seder, Eye Think, Inc.

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AESTHETICS OF THE BRIDGE

Carefully designed architectural embellishments in the then contemporary style of Art Deco add to the aesthetics of the Bridge. Once one knows what to look for, these features can be found in many places on the Bridge.

Design by Bob Reitherman, CUREE

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HOW THE BRIDGE SPANS THE GOLDEN GATE

The weight of the Bridge is handed off from one part of it to another to form a load path that transfers all that weight down to the foundations and into the ground. The weight of the deck and its traffic is carried up vertical steel suspender ropes to the curving main cables; those cables go over the tops of the towers, and then the towers must carry all that weight down to their foundations. Huge concrete anchorages at both ends of the Bridge resist the tension forces in the cables. A flip panel provides a cartoon graphic that illustrates this concept for a younger audience.

Design by Bob Reitherman, CUREE

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FOGHORNS

San Francisco is known for its fog, and the Golden Gate is the foggiest part of the region. Why? In the summer, the air over the land heats up, the molecules move faster and spread out, and that hot, light interior air rises. The denser (heavier) sea air pushes in through the only sea level gap in California’s coast range of mountains for hundreds of miles, bringing fog with it. The exhibit shows the phone number one can call when it’s foggy and the foghorn on the bridge is operating. One hears via the phone the foghorn sound almost instantly, but there is a distinct delay before the sound waves travel through the air to reach ones ears.

Design by Bob Reitherman, CUREE and Steve Gennrich, the Exploratorium

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TORSIONAL STIFFNESS OF THE DECK

Suspension bridges are flexible and move in the wind. After several high winds caused the Golden Gate Bridge to move excessively, the deck was retrofitted in 1953-1954 to increase its torsional stiffness. Hold out your arm horizontally like a bridge deck and twist it back and forth and that’s the kind of torsional motion a suspension bridge can experience. The Bridge’s stiffness to resist that twisting was greatly increased by adding bracing across the bottom of the deck structure. The models let the visitor feel that difference in torsional stiffness.

Design and fabrication by Elizabeth Deir and Professor Maria Garlock, Princeton University

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TOWER HEIGHT/CABLE TENSION RELATIONSHIP

A clothesline cannot be perfectly horizontal and still hold up the weight of the laundry -- it has to sag. The pulling force (tension) in a cable has to have an upward shape if it is to pull weight upward. One can feel how much more tension is required to lift the same bridge deck model if the sag is less (tower is shorter) than if the tower is taller with more cable sag. By pulling on the handles attached to the cables on the different tower heights, the visitor can feel and compare the amount of force needed to lift the decks.

Design and fabrication by Dave Fleming, Steve Gennrich, and Shawn Lani, the Exploratorium

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THE HISTORY OF THE BRIDGE

This set of nine panels and a large mural let the visitor imagine what it was like before there was a bridge across the Golden Gate. The panels highlight the issues involved in financing the project and obtaining approvals, the engineering required to design it, the stages of construction needed to build it, and the continuous work required to maintain the Bridge.

Design by Reed Helgens and Darryl Wong, CUREE

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VIBRATION OF THE BRIDGE

A suspension bridge is very flexible, and its shape changes slightly as it vibrates in the wind or during an earthquake. Each of these ways it can vibrate -- swaying back and forth like a swing, with an up-an-down wave motion, etc. -- is a different mode of vibration that this exhibit can visibly display as the visitor interacts with it.

Design and fabrication by Dave Fleming, Steve Gennrich, and Shawn Lani, the Exploratorium

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THE PAINTING OF THE BRIDGE

Steel rusts, and in a moist, salty environment like the Golden Gate, rust is a major challenge. The distinctive reddish-orange color of the Golden Gate Bridge was part of its aesthetic design, but the paint also protects the steel from rusting. Painted and unpainted pieces of steel let the visitor see the difference in durability over time.

Design by Bob Reitherman, CUREE

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SEISMIC ISOLATION

Approach spans leading to the Golden Gate Bridge from both the north and south are mounted on seismic isolators. These steel and rubber “sandwiches” reduce the severity of the shaking transmitted up into the structure. An actual isolator of the size and type seen nearby at the Bridge is shown in a cutaway view.

Design by Bob Reitherman, CUREE; fabrication by DIS; on loan from University of California Berkeley-PEER

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SEISMIC STRUT RETROFIT TESTING

This piece of a strut, made of small pieces of steel riveted together to form a lattice pattern, is a replica of a portion of the Bridge and was tested in compression until it buckled. Engineers use physical testing to validate and refine their calculations. Where original pieces of the Bridge need to be replaced as part of seismic upgrades, new large pieces of steel have holes laser-cut in them to make them look like the originals.

Test specimen courtesy of Professor A. Astaneh-Asl, University of California Berkeley Department of Civil and Environmental Engineering

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BRIDGE DECK AERODYNAMICS

The collapse of the original Tacoma Narrows Bridge in 1940 is a well-known bridge disaster. Like an airplane wing, the shape of the deck that the wind hits has much to do with whether the bridge deck begins to move excessively or remain stable. The scale models of the Tacoma Narrows Bridge deck and a modern aerodynamically designed one both move in the breeze -- the former quite noticeably, but the latter hardly at all.

Design and fabrication by Jon Raggett, West Wind Laboratory

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WEBSITE

Another element of the project has been the development of a website for the exhibition, providing information on each of the exhibits in nine languages in addition to English. The website can be accessed prior to or after a person’s visit to the Bridge, or while a visitor is there (using a smart phone to read a QR code that links to the website http://goldengate.org/exhibits). Links to relevant information about the Bridge that already exists on the Golden Gate Bridge, Highway and Transportation District website will be crossed-referenced within the exhibition webpage.

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EVALUATION

Evaluation of exhibits and other out-of-the-classroom learning projects includes front-end (baseline, or pre-project information collection, useful for pre- and post-project studies); formative evaluation (providing reviews of preliminary designs and prototypes to improve them); and summative or summary evaluation (done at the end of the project). On the Golden Gate Bridge project, two evaluation consulting firms were used: Inverness Research and David Heil and Associates.

Becky Carroll of Inverness Research trying out a prototype of an exhibit at the Golden Gate Bridge, providing input that subsequently refined the design.

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ACCESSIBILITY

A number of important accessibility design factors were taken into account: the wide age range of visitors, with implications for factors such as reading level and individuals’ heights; the need for multilingual exhibit information, especially important because the Bridge is a major international tourist destination; consideration of the needs of people who are blind or visually impaired, including graphic and typographic design; and mobility issues.

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BROADER IMPACT

Involvement of Engineering Students A dozen university students were able to get first-hand experience in a novel kind of engineering education – not only how to do engineering, but how to communicate engineering to the general public.

American Public Works AssociationA continuing education on-line course has been developed and delivered on the theme of Leveraging Public Works for Outreach & Education. Extensive communications have been sent to the 25,000 members of the American Public Works Association.

Bridge District General Manager Denis Mulligan reviewing scale alternatives for the large model of the Bridge with Princeton University civil engineering students William Plunket (left) and Gavin Daly.

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OUTREACH CONFERENCE: PUBLIC WORKS FOR PUBLIC LEARNING

From June 20 through 22, 2012, the project held an international conference in San Francisco, “Public Works for Public Learning.” The keynote speaker was Dr. G. Wayne Clough, the head of the Smithsonian Institution. The goal was to not only present the process and results of the Golden Gate Bridge project, but to showcase other examples where infrastructure has been capitalized upon to provide learning opportunities for the public. Speakers from the Eiffel Tower, Sydney Harbour Bridge, Hoover Dam, and Panama Canal, presented at the conference on their engineering landmarks that draw millions of visitors every year. Smaller public works were also included that demonstrated imaginative outreach programs for the general public, thereby showing that facility size and location were not a limiting factor in creating interesting public programs.

Conference attendees viewing many of the exhibit designs and prototypes. Dr. G. Wayne Clough, head of the Smithsonian Institution (shown far right) with Sylvester Black, the chief designer of the large model of the Bridge.

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Exhibition Project Team • Golden Gate Bridge, Highway and Transportation District: Denis Mulligan, General Manager and Principal Investigator of the project; Karen Collins, Mary Currie, John Eberle, Pete Guthlein, Kellee Hopper, Amorette Ko, Jeffrey Lee, Jorge Lee, and a number of ironworkers and painters involved in exhibit fabrication

• CUREE: Bob Reitherman, Reed Helgens, Darryl Wong

• Princeton University: Professor Maria Garlock, Sylvester Black; and a number of Princeton undergraduate and graduate engineering students

• LIFETILES - Eye Think, Inc.: Rufus Butler Seder

• The Exploratorium: Steve Gennrich, Dave Fleming, Shawn Lani

• West Wind Laboratory, Inc.: Jon Raggett

• Inverness Research: Becky Carroll, Michelle Phillips, Dawn Robles

• David Heil & Associates: David Heil, Shannon Weiss

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The contributions of recommendations of the Advisors to the project are gratefully acknowledged.

• 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, Representative of the American Public Works Association • Joyce Ma, Senior Researcher, the Exploratorium • Professor Henry Petroski, Duke University • Professor Stephen Ressler, U.S. Military Academy • Carol Willis, Director, The Skyscraper Museum

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This publication was produced by

Consortium of Universities for Research in Earthquake Engineering1301 South 46th Street, Richmond, CA 94804-4600 n tel: 510-665-3529 n fax: 510-665-3622

www.curee.org

CUREE

2013

Information on the Exhibition is available at:

http://www.goldengate.org/exhibits