The Ambitious Engineering Behind the Golden Gate Bridge

As many as a mil­lion peo­ple crossed the Gold­en Gate Bridge on foot to cel­e­brate the 50th anniver­sary of its con­struc­tion in 1987. More than a few of them would have remem­bered San Fran­cis­co as it was before it had its most icon­ic struc­ture — and indeed, some would even remem­ber walk­ing across it once before, on its inau­gur­al “Pedes­tri­an Day” in 1937. Bar­ring the pos­si­bil­i­ty of unusu­al­ly vig­or­ous super­cente­nar­i­ans, that won’t be the case 12 years from now, on the Gold­en Gate Bridge’s 100th anniver­sary. But we’ll still be able to appre­ci­ate the enor­mous ambi­tion of its builders, not least its chief design engi­neer Joseph Strauss, who, along with Charles Alton Ellis, made pos­si­ble a project long assumed impos­si­ble.

The video from Sabin Civ­il Engi­neer­ing at the top of the post explains every stage of the Gold­en Gate Bridge’s design and con­struc­tion. Build­ing a sus­pen­sion bridge over the Gold­en Gate, the deep strait between San Fran­cis­co Bay and the Pacif­ic Ocean, posed for­mi­da­ble chal­lenges. The dis­tinc­tive shape we know from so many pho­tographs emerged in part from the need to anchor the bridge in such a way as to bal­ance out the mas­sive forces that would oth­er­wise bend its tow­ers inward, and the steel-on-steel con­struc­tion of its sus­penders and deck was nec­es­sary to pre­vent cat­a­stroph­ic crack for­ma­tion.

The deck hangs from 250 pairs of cables, and each of the main cables that run the length of the bridge actu­al­ly con­sists of 27,000 steel wires wound togeth­er. A sys­tem of ther­mal expan­sion joints accom­mo­dates reg­u­lar elon­ga­tion and shrink­age of near­ly four feet.

And we haven’t even got into the under­wa­ter blast­ing and ter­ri­fy­ing-look­ing drilling work required to put up the tow­ers in the first place. In any case, the painstak­ing efforts of the engi­neers and labor­ers alike have sure­ly been vin­di­cat­ed by the Gold­en Gate Bridge’s func­tion­al­i­ty and pop­u­lar­i­ty over the past 88 years. Nat­u­ral­ly, it’s had to under­go con­sid­er­able main­te­nance and retro­fitting in that time, and it would take a true roman­tic to ignore its lim­i­ta­tions entire­ly. (Take its lack of rail capac­i­ty, which was nei­ther tech­ni­cal­ly nor eco­nom­i­cal­ly fea­si­ble to incor­po­rate dur­ing the Great Depres­sion.) Still, when 300,000 peo­ple jammed them­selves onto its deck at once on its 50th anniver­sary, it may have bent in the mid­dle, but it did­n’t break. That was a tes­ta­ment to the civ­il engi­neer­ing acu­men of Strauss and com­pa­ny — but let’s hope the cen­te­nary fes­tiv­i­ties are bet­ter orga­nized.

Relat­ed con­tent:

“The Bay Lights,” the World’s Largest LED Light Sculp­ture, Debuts in San Fran­cis­co

The 5 Inno­v­a­tive Bridges That Make New York City, New York City

How the Brook­lyn Bridge Was Built: The Sto­ry of One of the Great­est Engi­neer­ing Feats in His­to­ry

A Mes­mer­iz­ing Trip Across the Brook­lyn Bridge: Watch Footage from 1899

Why There Isn’t a Bridge from Italy to Sici­ly – And Why the 2,000-Year-Old Dream of Build­ing the Bridge May Soon Be Real­ized

Built to Last: How Ancient Roman Bridges Can Still With­stand the Weight of Mod­ern Cars & Trucks

Based in Seoul, Col­in Marshall writes and broad­casts on cities, lan­guage, and cul­ture. His projects include the Sub­stack newslet­ter Books on Cities and the book The State­less City: a Walk through 21st-Cen­tu­ry Los Ange­les. Fol­low him on the social net­work for­mer­ly known as Twit­ter at @colinmarshall.