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Nov 04, 2023

What's With the Golden Gate Bridge Look

Please try again Portugal has transformed into a tourism hot spot in recent

Please try again

Portugal has transformed into a tourism hot spot in recent years, and many Bay Area visitors have noticed something familiar in the capital city of Lisbon: There is a bridge that looks quite similar to our own Golden Gate Bridge.

Victoria Turner is a student at UCSF, and she wrote to Bay Curious asking: "How did we get the twin bridge of the Golden Gate Bridge in Lisbon? Why did they pick a similar color and style to the Golden Gate?"

It's a trickier question to answer than you might imagine, but here goes …

The bridge in Lisbon opened in 1966, nearly 30 years after construction finished on San Francisco's Golden Gate Bridge. It was originally called the Salazar Bridge, after Portugal's prime minister and dictator at the time. When a revolution overthrew the government in 1974, the name of the bridge was changed to the new independence date — Ponte 25 de Abril.

The bridges are actually quite different once you look closely, says Bart Ney, chief of public affairs for Caltrans District 4, but there are three big similarities.

First off, the color! Both bridges are a specific hue called international orange. It's not a common color choice for bridges, and it's been a distinguishing feature of the Golden Gate Bridge since it opened.

When the steel for the Golden Gate Bridge was brought on-site, it was coated in a red lead primer. The consulting architect, Irving F. Morrow, was weighing whether the color of the bridge should be as inconspicuous as possible — something like black or gray — or whether its color should call attention to it as a feature in the landscape. Ultimately, Morrow took inspiration from that red primer and how well it interacted with the green colors of the surrounding hills. He choose to paint the bridge international orange.

It was an unusual color choice for a bridge, but not a totally obscure color in the general scheme of things. International orange shows up often in the aerospace industry to set objects apart from their surroundings. NASA astronauts have worn international orange flight suits; the first airplane to break the sound barrier was colored international orange; and the color is often seen on tall antennae.

One question we haven't been able to fully answer is how the Ponte 25 de Abril in Lisbon came to be painted international orange. Some speculate it was to match the color of the tile rooftops in town. Architects also may have taken the lead from the aerospace industry, and chosen international orange to keep the bridge safe from airplane or ship strikes. Or, just maybe, they were inspired by the Golden Gate Bridge, and how its color made the structure iconic.

The second similarity between the Golden Gate Bridge and the Ponte 25 de Abril: They’re both suspension bridges. Though that almost wasn't the case! The design for the Golden Gate Bridge was originally a cantilever bridge that everyone thought was pretty ugly. An engineer named Leon Moisseiff proposed a suspension bridge instead. At that time steel was becoming a more popular choice for infrastructure projects, and suspension bridges don't require as much material, so it keeps costs down.

"In the case of, especially, suspension bridges, they’re very elegant structures," said Ney. "Beauty and function all at once."

The final similarity? Both bridges have been in James Bond films. The Ponte 25 de Abril was in On Her Majesty's Secret Service from 1969. (We couldn't find the full clip online, but a snippet from the Bond film appears in this YouTube video.)

The Golden Gate was a location for A View to a Kill, a 1985 James Bond movie with Roger Moore.

"There's probably structurally and architecturally a better comparison with the Lisbon bridge and another bridge that we have in the Bay Area," said Ney.

And that's the San Francisco Bay Bridge! Both the Bay Bridge and the Ponte 25 de Abril were built by American Bridge Company. (The Golden Gate Bridge was built by a subsidiary of Bethlehem Steel Corporation.)

"The [Ponte 25 de Abril] structure mirrors the Bay Bridge in the cross supports that you see in the towers to keep it strong. Both the Bay Bridge and the Lisbon bridge have crosses, and they also both have dual decks," said Ney. The Golden Gate, meanwhile, has more square-shaped supports.

Lisbon added a lower deck to the Ponte 25 de Abril in 1999 that carries 157 trains across it every day. Ney said that when the eastern span of the Bay Bridge needed to be replaced, it was important to work with American Bridge Company because of their experience adding that lower deck to the Lisbon bridge without closing the bridge to traffic.

"Bridges are very special for the communities that they serve, not just getting people around, which is their primary function, but in their identity," said Ney. "They make it possible for us to move goods and services, get where we need to go."

Despite the structural similarities between the Bay Bridge and the Ponte 25 de Abril, Ney doesn't expect people to stop comparing Portugal's bridge to the Golden Gate Bridge anytime soon.

"I think just about any bridge gets compared to the Golden Gate," he said. "It's one of the most beautiful bridges on the planet Earth. It's arguably one of the few times man has improved on nature."