Blog: Did You Think of That?

Article By : Junko Yoshida

The fire at Notre Dame is a reminder that system engineering neither begins nor ends by developing the most advanced technology.

The fire at Notre Dame is a reminder that system engineering neither begins nor ends by developing the most advanced technology. More important is to perceive potential "foresight gaps" – anticipating how the completed system will be used.

“Did you think of that?” is not exactly the question a design engineer wants to hear – especially after he has just (allegedly) designed the latest, the greatest and the most advanced life-saving system ever devised.

But that’s a question often posed by Phil Koopman, professor at Carnegie Mellon University’s department of Electrical and Computer Engineering. It's not enough that a product performs the function it's designed for. It's important to also anticipate what will happen to that product out in the world.

In a recent EE Times on Air Weekly Briefing interview, Koopman offered a couple of examples of this ego-deflating query, but one of my favorites was this:

…if you’re in an autonomous vehicle, and let’s say you’re the passenger asleep in the back seat, and all of a sudden, all the cameras and the lidars are coated with mud, and that wiper fluid isn’t there to clean things off. Now you’ve got a problem. You’ve got a vehicle going at speed that can’t see…

Did you think of that?

My colleague Brian Santo recently wrote about LED streetlights for our sister publication EDN.

An astute reader responded to Santo’s story by quoting a Canadian Broadcasting Corp.'s report. The CBC story notes that “new LED lights don't generate enough heat to melt snow.” One city official said, “Traffic signal lights at some intersections throughout the city… have become partially obscured by snow frozen to the lens.”

LED traffic lights probably are still a good idea. But they might require cold-climate cities to put a heater in every traffic light.

Did you think of that?

Foresight gap

The horrific image of the Notre Dame’s spire burning down — unfolding on live television last week — haunts us still.

The most agonizing thing, at least for me, was that everything seemed to be happening in slow motion. Where are the firefighters? Have the ladder trucks arrived on the scene yet? Why am I not seeing water splashing on the roof?

Then, I started asking myself: Where were the smoke detectors? To protect such a national treasure, surely, even a building 850 years old must have smoke alarms that will alert the fire department at the first whiff. N’est-ce pas?

Notre Dame's timber roof before the fire

Notre Dame’s timber roof before the fire (Photo credit: David Benjamin)

Working for a publication like EE Times, in which we often write as though the “connected world” is a given, and where we’re told daily that IoT devices are going “save our lives,” I was assuming that smoke alarms inside Notre Dame are “connected” and designed to set off instant alarms at Fire Dept. Central.

According to the New York Times, I was wrong in several ways.

  1. Yes, there are smoke detectors. But fire alarms in Notre-Dame did not notify fire dispatchers.
  2. When the alarm sounded, a fire security agent alerted church employees.
  3. A church guard then climbed a steep staircase to assess the attic before the fire department could be notified.
  4. It took six minutes to get up to the attic.
  5. The guard did not see a fire and went back to the ground and issued the “all clear.”
  6. Twenty-three minutes after the first alarm, a second alarm sounded.
  7. Two church employees climbed back up. By this time, the flames were blazing out of control. On their way down, they realized they had locked the door (and access to the fire). They had to go back to open it.
  8. Thirty-one minutes after the first alarm, the church finally called in firefighters.

As the Times confirmed with a spokesman for the Paris Fire Brigade, we now know that fire alarms in France never automatically alert fire departments.


To avoid false alarms and “to remove doubt,” firefighters ask that someone go check first before reporting the fire, according to the Fire Brigade’s spokesman. I hope I’m not the only one who gasped at this classic chapter from the French bureaucrat’s Red Tape Manual.

French bureaucracy aside, the very fact that fire detectors in a monument as historic and iconic as Notre Dame were NOT connected directly to alarm boxes at the Paris Fire Brigade freaked me out. These modern smoke alarms in Notre Dame essentially required church employees to play a role not so different from what Quasimodo would have done by scurrying up to the bell tower.

Did you think of that?

The question should not apply only designers of fire alarms, but also to their suppliers and installers.

The fire at Notre Dame is a reminder that system engineering neither begins nor ends by developing the most advanced technology. More important is to perceive potential “foresight gaps” – anticipating how the completed system will be used and what could happen once it’s installed in the real world.

Perils of false alarms

The Fire Brigade spokesman’s comment also highlights the dilemma of “false alarms.” False alarms burden emergency resources and they cost money. In some instances, the fear of false alarms makes it more likely that an alarm owner will leave it unarmed.

Design engineers might have developed a great alarm system. But it saves no lives and spares no cathedrals if the people who use them don’t understand how they work and operate in mortal dread of false alarms.

Untested assumptions

The foresight gap isn’t the only trap in the question, “Did you think of that?”

An untested assumption is another factor that exposes the architect who oversaw the design of the fire safety system at Notre Dame. He assumed the truth of what appears to be common lore in France — that fires in heavy timber, in buildings that date to the 19th century, are “slow burning.” It’s definitely not easy to start up a fire on a single piece of ancient hardwood. But once the surface of a vast forest of oak timbers in the attic of Notre Dame was covered in flame and building heat, the fire built up too rapidly to put out.

If anything, the horrific fire at Notre Dame reinforces the importance of filling in the foresight gap and questioning untested assumptions. It should inspire everyone to join Prof. Koopman in asking, “Did you think of that?”

Having brought it up, EE Times is now looking for more “Did you think of that” anecdotes. Please share your own experiences (or those by others) and insights in the comments section below.

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