The Golden Gate Bridge

1.

The Golden Gate Bridge
How the “bridge that couldn’t be built” became San Francisco’s icon

2.

The bridge at a glance
4,200 ft
746 ft
1.7 mi
~112,00
0
Main span between
the towers (1,280 m)
Tower height above
the water (227 m)
Total length including
approaches
Vehicles crossing on
an average day
Opened May 1937 · Connects San Francisco with Marin County across the Golden Gate strait
The Golden Gate Bridge
2

3.

Why bridge the Golden Gate?
Ferries were the only link
Marin County and the north were reachable from San
Francisco only by boat.
A hostile strait
Deep water, fast tidal currents, fog and ocean winds
made a crossing seem impossible.
Strong opposition
$35M
Bond issue approved by district
voters in 1930, in the depths of the
Great Depression
The War Department, ferry operators and skeptics all
fought the project.
The Golden Gate Bridge
3

4.

The minds behind the bridge
Joseph Strauss
Charles Ellis
Chief engineer and tireless promoter
who pushed the project for over a
decade
Did much of the structural
mathematics; his role was officially
recognized only in 2007
Leon Moisseiff
Irving Morrow
Suspension-bridge expert whose
deflection theory allowed a slender,
flexible deck
Architect behind the Art Deco towers,
lighting and the famous orange color
The Golden Gate Bridge
4

5.

Four years to build: 1933–1937
Jan 1933
1933–35
1935–36
Late 1936
May 1937
Construction begins
Towers rise; south
tower built in open
water
Main cables spun
wire by wire
Roadway deck
completed across
the gap
Pedestrian Day,
then opening to
cars
The Golden Gate Bridge
5

6.

A new standard for worker safety
Hard hats
19
11
Men saved by the
safety net: the
“Halfway to Hell
Club”
Workers lost, ten of
them when a scaffold
tore through the net
in 1937
The Golden Gate Bridge
Required on site, an early use of mandatory
head protection
A net under the deck
Strung beneath the work area from end to
end
Tie-off lines
Workers were secured while working at
height
6

7.

Held up by two enormous cables
27,572
80,000 mi
36⅜ in
The Golden Gate Bridge
Individual steel wires bundled
into each main cable
Total length of wire, enough to
circle Earth three times
Diameter of each main cable
(about 92 cm)
Built to move
The deck can sway sideways by
roughly 27 ft in high winds
Main cables run over the
towers to massive concrete
anchorages on each shore
Seismic retrofits since the
1990s help it ride out major
earthquakes
7

8.

World’s longest span for 27 years
Main span length (m), record holders
Golden Gate (1937)
Verrazzano-Narrows (1964)
Humber (1981)
1937 → 1964
1 280
The Golden Gate held the
record for the longest
suspension span until New
York’s Verrazzano-Narrows
Bridge opened, beating it by
only 18 m.
1 298
1 410
Akashi Kaikyō (1998)
1 991
1915 Çanakkale (2022)
2 023
The Golden Gate Bridge
8

9.

Why it’s orange, not gold
International Orange
Bay fog & water
The name comes from the strait, not the paint
“Golden Gate” described the entrance to the bay decades
before the bridge existed.
Morrow picked the primer’s color
He liked the orange-red steel primer and argued it suited the
landscape. The Navy had wanted black with yellow stripes for
visibility.
Painting never stops
A permanent crew touches up the steel to fight salt-air
corrosion.
Golden hills
The Golden Gate Bridge
9

10.

Still an icon today
~112,000 vehicles
300,000 people
All-electronic tolls
Modern Wonder
cross on an average day
packed the deck at the
1987 50th anniversary,
flattening its arch
since 2013, with no toll
booths
named by civil engineers
(ASCE) in 1994