Craftsmen built Notre Dame eight centuries ago. Now it may be up to robots to save it.
Craftsmen
built Notre Dame eight centuries ago. Now it may be up to robots to save it.
Peter Holley, The
Washington Post Published 4:45 pm PDT, Tuesday, April 16, 2019
As the first images of charred wreckage inside
the Notre Dame cathedral appeared online Tuesday, engineers around the world
said one observation was already clear: To return the ancient structure to its
glorious past, builders will likely have turn to cutting-edge technology that
many associate with the future.
Even before engineers had been able to access
the deepest corners of the still-smoldering structure, design experts,
preservationists and engineers were contemplating which modern technologies
might be brought to bear to restore one of Europe's most iconic structures to
its fabled past.
It's a speculative exercise, they admit, but one
that is to be expected with the future of a UNESCO World Heritage Site at
stake.
The rebuilding effort will likely draw upon
expertise gleaned from disasters like the Fukushima Daiichi nuclear disaster in
Japan and the Brazilian National Museum fire, where experimental robots and new
digital tools have been used to go places people cannot safely venture and
replicate detailed artifacts lost to fire.
Throughout the rebuilding effort, experts say,
engineers and preservationists will be forced to wrestle with an ever-present
question.
"How do they meld brand new 21st century
technologies with ancient craftsmanship and building trades in ways that keep
the cathedral preserved and alive?" said Katherine Malon-France, the
interim chief preservation officer of the National Trust for Historic
Preservation, a privately funded nonprofit based in Washington. "This is
going to be a very interesting intersection of technology and craft, and the
world will be closely watching how they pull it off."
Some of the technology that will be used to
restore Notre Dame has already been on display. As a wall of orange flames
roared across the cathedral's roof Monday, and hundreds of firefighters mounted
their counterattack, high-tech machines had already been brought to the fight.
Hovering in the air above the cathedral, a pair
of Chinese-manufactured commercial drones equipped with HD cameras - the Mavic
Pro and Matrice M210, made by DJI - helped firefighters position their hoses to
contain the blaze before it before it destroyed the cathedral's two, iconic
belfries, according to the French newspaper Le Parisien.
"It is thanks to these drones, to this new
technique absolutely unavoidable today, that we could make tactical choices to
stop this fire at a time when it was potentially occupying the two
belfries," Paris firefighters spokesman Gabriel Plus said.
On the ground, Colossus, a robotic fire
extinguisher, blasted the nave with water, lowering the temperature of the
glass-filled room, the paper reported.
In the crucial months ahead, experts say, some
of that same technology will likely be used to return the 13th-century
cathedral to a place that last year drew 12 million visitors.
One way to start, the experts said, will be to
bring in other drones to survey locations inside the vast cathedral that are
too dangerous or damaged for engineers to reach.
Jerry Hajjar, a civil engineering professor at
Northeastern University, said drones can be equipped with sensors - such as
small cameras and laser scanners - that will allow engineers to document fire
damage and create highly accurate three-dimensional visions of specific
locations inside the church.
Hajjar said other sensors may be able to peer
inside the church's walls like an X-ray and estimate the mineralogical
properties and the degree of stress the structure is under. But the
documentation effort could prove more difficult than it sounds, Hajjar said,
noting that the higher a drone must rise, the lower its the battery life and
the amount of time it can stay in the air. That could prove especially
challenging, he said, in a building that reaches 226 feet off the ground.
Another method for testing the cathedral's
integrity could involve robots, Hajjar said, pointing out that research is
already underway for using climbing robots to inspect and repair steel bridges.
"The value of using robots became very
apparent after the Fukushima disaster," Hajjar said. "They didn't
want to send people inside because it was too dangerous, but realized they
could use crawling robots to go inside the site and get valuable images."
It's possible that much of the 3D mapping work
engineers will be called upon to consult already exists. In 2015, Andrew
Tallon, an associate professor of art at Vassar College who died last year from
brain cancer, told National Geographic that he'd completed a comprehensive
laser scan of the entire cathedral. Experts said Tallon's digital techniques
could provide crucial information for any rebuilding effort.
There's only one problem: It's not entirely
clear where Tallon's scans, which could be stored on a single hard drive, are
currently located, according to The Atlantic.
A popular video game also could provide another
source of digital information about the Notre Dame. In a 2014 article in the
Verge, Caroline Miousse - an artist who worked on the video game Assassin's
Creed - said she devoted two years to creating a model of the church that
captured the inside and outside of the building.
Once engineers have a clearer sense of the
church's structural integrity, experts said, they'll be able to design a
suitable roof. They'll have to decide whether to rebuild the roof framing with
timber. If they don't opt for a structurally engineered wood, which could
reduce the roof's weight and offer artistic freedom, engineers could choose to
work with steel.
Though it would depart from the church's
original wooden roof, steel would allow engineers to use less material and be
even lighter than wood, according to Gary Howes, COO of The Durable Group, a
consortium of historic restoration companies.
Replacing what was lost may not be the biggest
challenge, Howes said. Instead, he said, it will be marrying the old and the
new, offering the building's worldwide admirers a window in the past that
includes upgrades and meets modern building codes.
"This project is going to be more about
emotion than structure," he said. "Everybody wants that cathedral to
look like it has always looked, the way they remember it."
Fortunately, Howes added, France has an
advantage over the rest of the world.
"Some of the best craftsmen in the world
are located in France," he said. "Whether it's restoration or even
contemporary work, they haven't lost the historic trades like we did here in
the U.S. Each year, we go there to learn from them."
James Shepherd, director of preservation and
facilities at Washington National Cathedral, where damage from a 2011 earthquake
is still unrepaired, said the immediate days after an event like Monday's fire
will be a critical time for the Notre Dame.
"They'll need expertise there to make sure
that they're sorting through the rubble and pulling out things that are
salvageable or not," Shepherd said. "You're talking about things that
might be 700 or 800 years old that they're trying to pull out that might be
partially burned or partially damaged by water."
In Brazil, where fire destroyed 90% of the
national museum's collection last year, preservationists have used 3D data to
re-create precious objects lost in the fire. Assuming they have access to
similar data, experts said the same technique could be used in Paris.
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