The Drones And Robots That Helped Save Notre Dame

In the era of social media, events such as the fire at Notre Dame cathedral are experienced by a global audience in real-time. From New York to Tokyo, millions of people were glued to their smartphones and computers, waiting for the latest update from media outlets and even individuals who were on the ground documenting the fearsome blaze. For twelve grueling hours, the fate of the 850 year old Parisian icon hung in the balance, and for a time it looked like the worst was inevitable.

The fires have been fully extinguished, the smoke has cleared, and in the light of day we now know that the heroic acts of the emergency response teams managed to avert complete disaster. While the damage to the cathedral is severe, the structure itself and much of the priceless art inside still remain. It’s far too early to know for sure how much the cleanup and repair of the cathedral will cost, but even the most optimistic of estimates are already in the hundreds of millions of dollars. With a structure this old, it’s likely that reconstruction will be slowed by the fact that construction techniques which have become antiquated in the intervening centuries will need to be revisited by conservators. But the people of France will not be deterred, and President Emmanuel Macron has already vowed his country will rebuild the cathedral within five years.

It’s impossible to overstate the importance of the men and women who risked their lives to save one of France’s most beloved monuments. They deserve all the praise from a grateful nation, and indeed, world. But fighting side by side with them were cutting-edge pieces of technology, some of which were pushed into service at a moments notice. These machines helped guide the firefighters in their battle with the inferno, and stood in when the risk to human life was too great. At the end of the day, it was man and not machine that triumphed over nature’s fury; but without the help of modern technology the toll could have been far higher.

Eyes in the Sky

As reported by the French media, emergency response teams utilized at least two UAVs to perform reconnaissance over the burning cathedral. With imagery provided by these platforms, firefighters were able to see the intensity and movement of the fire in real-time. These UAVs were not only faster and cheaper than sending in helicopters, but their operators were able to get much closer to the fire as they were not as susceptible to the heat and smoke which would have kept manned aircraft at a respectable distance.

Mavic Pro

But as it turns out, the Paris Fire Brigade didn’t actually have UAVs of their own which could be used in this situation. They instead borrowed two commercially available models which were in service with the Ministry of the Interior and the Ministry of Culture. Both of these quadcopters, a Mavic Pro and Matrice M210, are products of the Chinese company DJI. A manufacture that’s nearly synonymous with “prosumer” aerial photography platforms, they also produce the extremely popular Phantom series of quadcopters.

The Mavic Pro is a small semi-autonomous quadcopter that DJI advertises as  being ideal for capturing high quality video at the spur of the moment thanks to a folding design which makes it much easier to transport than more traditional quadcopters. With a flight time of nearly a half-hour, a 4K camera stabilized with a three axis mechanical gimbal, and the ability to automatically track and orbit objects selected by the operator, it proved to be an ideal way of monitoring the fire from above.

Matrice M210

Compared to the Mavic, the Matrice M210 is part of DJI’s professional line of quadcopters. Larger and more powerful, this UAV is designed to carry various payload packages such as spotlights, thermal cameras, and optical zoom cameras. There are conflicting reports as to whether or not the M210 used by the Paris Fire Brigade had the thermal camera option installed, but in any event, it would have at least given them another source of high resolution video.

It’s interesting to note that in general the operation of UAVs is strictly prohibited in Paris, and that geofencing functions built into DJI’s products would have normally prevented them from flying over Notre Dame. But DJI actually has a system in place where operators can request these limitations be lifted temporarily, which allowed the manufacturer to work quickly with the French authorities to get the UAVs airborne given the severity of the situation.

On the Shoulders of a Colossus

While consumer products might have been up to the task in the sky, the situation on the ground was no place for an amateur. To actually enter Notre Dame and try to battle the fire from within, the Paris Fire Brigade utilized the Colossus. This 500 kilogram tracked platform developed by Shark Robotics is essentially impervious to fire and water, and when combined with a motorized water cannon, makes a potent firefighting asset.

Colossus was especially useful during the Notre Dame fire because it was able to remain inside the structure while the roof was engulfed in flames. With flaming debris falling from above, and the ultimate collapse of the cathedral’s iconic lead-and-wood spire, the interior was a particularly dangerous area for human firefighters to operate in. Colossus was able to provide a continuous deluge of water in the church’s nave even as the structure literally fell apart around the robot, the cooling effect of which is already being credited for helping to save priceless stained glass artwork. In addition, it gave firefighters another live video feed so they could determine when it was safe enough to send in additional crews.

A High-Tech Restoration

Cutting edge technology and robotics played a role in saving Notre Dame cathedral, and it seems likely their work isn’t done quite yet. As we’ve seen in previous disasters such as the nuclear meltdown at Fukushima Daiichi plant in Japan, robots could be called in to survey the structural integrity of areas which are too dangerous for human workers. From the air, UAVs with high-resolution cameras will be able to rapidly image the entire site, which could be used to create a three dimensional model of the structure through photogrammetry; aiding in the eventual design of a modern roof which blends into the original stonework.

In order to restore Notre Dame within the ambitious five year timeline given by President Macron while maintaining a safe working environment for the thousands of workers which will be involved in the project, no option will be off the table. The people of France have been galvanized by this event, and before it’s all said and done, we may see new cutting-edge solutions specifically developed for the unique challenges of this reconstruction. The burning of Notre Dame may be a tragedy of historic proportions, but the lessons it will teach us could benefit the world in ways that today we can’t even imagine.

[Main image source: Agence France Presse]

61 thoughts on “The Drones And Robots That Helped Save Notre Dame

  1. I’m just glad to hear that it wasn’t completely destroyed. I look forward to following the rebuilding process.
    Let’s hope they add a full fire suppression to the cathedral (including the attic) system during the rebuild. It would be a shame to see this sort of thing happen again.

      1. If it were in the US, the government would award a billion dollar contract to the husband of some bureaucrat who’s experience consists of running a landscaping business, because… capitalism.

  2. If I were a firefighter, I’d be SO TEMPTED to target practice with my fire hose on the drones!

    “Oops! Sorry boss, it just flew between me and the spot I was trying to soak! Several times…”

    1. I think new laminated wood beams would be an appropriate “new” technology to use for the new roof. Unlike steel beams, laminated wood beams would still preserve the character of the wood structure, and unlike ancient oak, they would also be easy to source. They should also easily meet the engineering requirements.

      1. But then again, for a part of the structure that is normally completely unseen, steel may be the better choice. I suppose it depends upon the will of whoever is put in charge of the rebuild. Hopefully it won’t be a committee that makes all the decisions. That’s how you get bad choices.

          1. When I visited one of Shakespeare’s homes in Stafford-on-Avon a couple years ago, I asked how much of the structure was original. The tour guide said around 20%.

    2. Oops.. accidentally got this reply attached to the wrong comment below… meant to post it here…

      I totally understand the argument about historical accuracy, but…

      Every single fiber within me rebels at the idea of rebuilding the attic the way it was.

      It’s almost like you were building a structure *designed* to burn. A big forest of timbers, in a nice open grid with plenty of air circulation between them, and a lot of vertical orientations (gotta think flame propagation) all sealed up in a hot environment that purposely keeps them as dry as possible.

      Helpfully, the space is also isolated away from where people would normally notice a problem early and awkward enough to discourage regular inspection when an alarm does trigger (as happened Monday, where the initial fire went 23 minutes from first sensor alarm to actual identification as a real problem).

      Also, a place that, lightning rods notwithstanding, gets hit by lightning. A lot. The images are cool, but in retrospect, pretty ominous.

      I know if I were in charge of rebuilding this church I’d take one look at the rate at which large historic buildings in Europe burn and fight tooth and nail for a nice, light, *flameproof* steel truss.

  3. I didn’t find it just now while searching, but I read a number of years ago about a movie being considered that had the Familia Sagrada in Barcelona being finished with a type of 3-D printing…

    1. Came to the comments to make sure this was here. While new data will need to be collected to asses the current state of the structure, this is absolutely another example of technology that can benefit reconstruction efforts in a really big way.

  4. “saved” Notre Dame ? really ? Save like only half destroyed ?

    And this: “construction techniques which have become antiquated in the intervening centuries will need to be revisited by conservators”

    Dear misinformed writer from overseas, learn that the “antiquated techniques” as you name them have not been lost, are still valid, and have been perpetuated through centuries until today.

    For the simple reason that most of the cathedrals in Europe aren´t YET finished and are still a work-in-progress. There are thousands of very specialized people extremely talented that are stone cutters, carpenters (…) who still went to the same learning process that exist here from the middle-age: https://en.wikipedia.org/wiki/Compagnons_du_Devoir

    Those are excellent labourers, whose skills helped build and renovate famous buildings all over the world.
    So yes, they learn those “antiquated techniques” and I very very much doubt than an overseas hacker squirting melted plastic will repair the roof of Notre Dame: they will use the same techniques, the same materials, the same processes. It won´t be RoHS too: they´ll put the same tons of lead to covers the roof.

    It will cost a lot, that´s sure. But claiming “antiquated techniques” will be replaced by modern technology is … an heresy.
    modern technology will help, as are lasers developed specially to clean the stone from the damages of pollution, precision tools that are measuring alignment over hundreds of meters, 3D scanners …

    The most accurate 3D maps of this building were actually acquired some months ago for a video game.

    But the techniques and materials will mostly remain the same: you can be sure at this moment the most beautiful oak trees are chosen to be cut and will dry slowly over the next 10 years to take part in the build.
    And the most skilled workers will have a lifelong job on this monument.

    1. “Dear misinformed writer from overseas, learn that the “antiquated techniques” as you name them have not been lost, are still valid, and have been perpetuated through centuries until today. ”

      I support the funding on a restoration of an old church here in S.E. Minnesota. It was built using local limestone.
      The “mortar” between the stone was failing in a number of joints, and people were wondering how to repair them.
      Some, just thought all it took to do would be to buy mortar mix and squeeze it in the joints.

      As “luck” would have it, one summer, a stone mason from Germany and his American born wife were visiting her relatives in a nearby town. He (somehow) learned of the restoration project and visited the people on the restoration committee.
      He informed them of the type of mortar that needed to be used and how to make it, taught volunteers the “point and tuck” process, and also replaced one of the broken stones with one he cut from the original quarry.

      Without his expertise, a restoration attempt on the joints would likely have increased the damage to the structure.

      1. While the antiquated techniques to restore the structure exist today, it will take years to train enough people to make the antiquated repairs.

        Notre Dame fire: Macron’s five-year rebuilding pledge is unrealistic, experts warn

        “Cathedrals often took more than a century to build in medieval times, a process that sometimes spanned the lives of several monarchs.”

        “The Gothic cathedral in Cologne, Germany, was badly damaged during World War II and work to repair it is still going on more than 70 years later.”

        https://www.nbcnews.com/news/world/notre-dame-fire-macron-s-vow-rebuild-cathedral-unrealistic-experts-n995311

          1. >> without bureaucracy <<
            Yes! And without all the the commitees to decide:
            1/ at which age it will be restored (Before after viollet-le-duc)
            2/ With/Without "la flèche" and if with glass/metal/wood/…
            3/ Framing (may be the longest choice) wood/steel/concrete (my personal choice after seeing Reims restored with the money of the Rockfeller family)

    2. “Antiquated” != “Bad”, and I don’t see anywhere that Tom suggested this was so.

      The way they did things 900 years ago is simply amazing, and deserves to be celebrated wherever possible. But it’s a simple fact that a lot of progress has been made in engineering in the last 900 years, and we ignore that at our peril. Would you prefer the rest of the structure be demolished if it can’t be restored safely using the exact materials and methods that were available in the 12th century? Because that’s about the only option in a world where old-growth oaks are no longer a thing.

      I don’t want to see steel beams and plywood up there, but it seems like we can engineer some kind of solution that pays respect to the original makers while still making a structure that will stand for many ages, and remains safe for people to come and witness the glory of what both the original builders and the restoration team accomplished.

        1. Very, very few people ever saw the ‘forest’ of roof timbers in the cathedral because the ceiling of the cathedral is stone vaulting, the roof timbers were above the stone vaulting and supporter the roof. Most of the stone vaulting survived the fire.

      1. Survival bias comes into play, but everything that has stuck around for 900 years must have been built pretty well. How many buildings constructed today will be around in 900 years? Stick to the old methods for a restoration, but use modern tools to help speed things up like hydraulic lifts and cranes.

    3. “an heresy” just saying rebuild the English language back in elementary school….shouldn’t that be “a heresy” if we were to rebuild it proper…..seems like the ancient stone carvers and carpenters with draw knives might have to check the ancient text to see which end of the beam goes up first. Let’s not fight, children over old or new methods….just remember to check the instructions in the paint by number kits for the art work and the Legos when we rebuild it.

      Yuh”an h

  5. The trick is that the 400 firefighters already knew the site.. perfectly, because they already practised on site, and they had an action plan and an “appropriate” site-specific training.

    When they arrived on site, it was too late, so they sacrificed the roof in order to keep the towers intact. The only guideline was “no further propagation”.

    So the drone tools are not so interesting in that scenario. Only the firefighter bot.

    Too bad the guards did not took the fire alarm seriously, on the first alarm, and call the fire brigade.

  6. (…) buildings collapsed (in) Marseille => It happened so quickly that no one would have been able to bring a bot…

    (…) But now, 750 million euro because it is a catholic church, in a catholic country (…) => In France the government is separated from religions since 1905. Today, secularism is considered seriously in France: for example, every year some public town hall are forced to remove the christmas crib.
    You also made a mistake: in France, in 1905, every religious building became the property of the French state (and not only catholic buildings). Only buildings built after that (so not with public money) do not belong to the French state. Notre Dame de Paris was built 800 years ago, so it belongs to the people. People that use this place for religious activities must pay a rent for doing so.
    On the other side, I feel really sad that some people (some of the richer French person) are able to pay 200.000.000 euros … It’s 200 times all the money I may earn in my life … But this money will not be paid by the French state.

    (…) It is an absolute non-event (…) : Even if I am agnostic, I feel really sad that this historic monument was damaged … It’s not a thing you buy one day, and throw 12 months after … It’s a part of my country history.

    My point is hackaday would be better on focusing on D.I.Y. projects (…) => please write us a famous article on what you’ve done (something interesting, not a “non-event” ;) !

    Why this is an HaD interesting article ? Macron (French president) said that this must be repaired in 5 years (before the Olympic Games in 2024 that will help richer guys to become richer). This is a really challenging event that may lead to some innovative techniques that will have a place here, let’s see: cut trees, and make them dry slowly before processing them and installing them requires lots of years … not 5 years … that’s why it’s really challenging :) (I am ironic) Seriously, when he eared that, an old friend of mine said “to grow a centenary oak, you can put any fertilizer you want, you need to wait 100 years”…

  7. Any reason there’s not huuuuuuuuuge CO2 or other inert gas type suppression systems carefully retrofitted into these kinds of buildings? Appreciate the spaces are massive so the volume of gas to protect the whole structure would be huge (and I’m sure over pressuring things like stained glass windows would be bad) but surely a good idea in general?

      1. Totally – but fire is also pretty dangerous. 3M makes a product that strikes a balance between smothering fires without suffocating humans.
        Something like inergen is a good replacement for CO2 or the older Halon type systems.

    1. “Unprovoked” by the cathedral, yes.

      It reminds me that radio broadcasts by the Germans condemning the bombing of such historical edifices, helped the Allies increase their accuracy for future bombing runs.

  8. Macron and mayor Anne Hildago, as public contracts lovers (half the streets of the capital are in a perpetual state of reconfiguration..), are hand in hand to lead the event named “Paris Olympics 2024”, decided despite the unfavorable opinion of most Parisians.
    And alongside, a much more “harder to swallow” ongoing project has been quietly announced and planned since the end of 2016 : a full refactoring of Notre-Dame surroundings, with a glass floor (covering an underground retail mall) facing the church, and glass structures on top of every historical buildings of the city island ! (probably aimed at hosting more luxury hotels owned by wealthy Middle-East tyrants).

    See it for yourself, and let people know : https://www.designboom.com/architecture/dominique-perrault-philippe-belaval-mission-ile-de-la-cite-paris-03-13-2017/

    What is probably the biggest real estate operation the country has ever known has been officially commissioned by the presidency and town hall, and publicly presented somewhere.. And they already relocated almost all historical public services and authorities present for centuries (police headquarters, justice courthouse, public hospital) from each of their famous symbolic buildings.
    Most citizen are still unaware and obviously, Heritage Protection advocates already fear it with reasons, but Notre-Dame “with a brand new roof ready for the Olympics” will now perfectly integrate into it…..

  9. Don’t get me wrong, I feel sorry for the chatedral, but at the same time I feel immense injustice when I see so much fuss going on because of a fire in one French 800 year old chatedral. Do you know that thousands of churches​, temples, monasteries, chatedrals and mosques have been destroyed in the last 20 years. Hundreds of churches, temples and monasteries were destroyed (burnt, bombed or vandalized) only in Kosovo in a single year by Kosovo militants, many of which were older than Notre Dame, and some twice as old, and all featuring priceless arts. Yet no one even mentions them.

    1. ” a single year by Kosovo militants, many of which were older than Notre Dame, and some twice as old”

      Wow! 800 to 1600 year old militants! Where is their “Fountain of Youth”?
      B^)

    2. Yes, and that’s without saying that France is one of the top 10 richest countries, yet they ask for donations (for which every donor can ask for between 66% to 75% tax reduction), they get a huge amount of money, mostly from companies (including companies that actively avoid paying taxes, like Apple), close to a billion dollars has been promised/collected (probably more of what they can spend for this, and magnitudes more of what would have cost installing an automatic fire suppression system up there…it’s not like this has not happened in the past, nor that wood that dried for 800 years is not flammable…), and then sets a 5 year deadline, which how surprisingly matches the 2024 olympics that no parisian wanted (they refused to do a referendum because they’d loose it…)

      Can you imagine how many things can be done with one billion? There are natural and human catastrophes every day that could benefit from the “generosity” from those companies…which could also actually pay taxes too…but I suppose that having their name on the most visited monument in France and Europe does gives some visibility…

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