The following is an excerpt from How Infrastructure Works: Inside the Systems That Shape Our World, by Deb Chachra.

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How Infrastructure Works: Inside the Systems That Shape Our World

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On a rainy Mother’s Day in 2002, along with two hundred thousand other people, I went for a walk on a brand-new bridge.

The Leonard P. Zakim Bunker Hill Memorial Bridge in Boston is brilliant white, all soaring towers and parallel lines, echoing a nearby obelisk and evoking a ship under full sail. It’s one of the world’s widest cable-stayed bridges, and its roadbed carries ten lanes of Interstate 93 traffic over the Charles River before diving under the peninsula of the downtown core. A few weeks before it was opened to cars, local residents were invited to cross it on foot. And we came, five times as many visitors as were expected, despite the weather. My friend and I waited for hours, huddled under our umbrellas, before we finally made it onto the bridge. We craned our necks to drink it all in, knowing it was almost certainly the one and only time we would get to traverse it at our own speed and under our own power.

In retrospect, the organizers probably shouldn’t have been quite so surprised at the demand. In 1987, when the Golden Gate Bridge was fully opened to pedestrians to celebrate its fiftieth anniversary, nearly three hundred thousand people were on the deck—more weight than bumper-to-bumper traffic—and the organizers had to turn away another half a million.

Conservation biologists sometimes refer to animals like pandas, elephants, and polar bears as “charismatic megafauna.” Large, easily recognizable, and beloved, they make excellent spokescreatures for wildlife and for their homes. All over the world, charismatic megastructures are the public faces of our collective infrastructural systems. Bridges, of course, but also the soaring spaces of railway stations, from Grand Central Terminal in New York City to the Chhatrapati Shivaji Maharaj Terminus in Mumbai. In my hometown of Toronto, the CN Tower, built to be a communications hub, makes the skyline instantly recognizable. The Hoover Dam, in the desert outside Las Vegas, hosts seven million visitors every year. We love our charismatic megastructures. Their size and complexity might inspire awe, but I think it also has to do with the way that we feel like they belong to all of us, not individually but together, in much the same way as cathedrals and other sacred spaces. Not for nothing did Joan Didion describe driving on Los Angeles highways as a “secular communion.”

Years after I dragged my friend out in the rain with me to walk on the Zakim Bridge, my nephews came to visit and we took  an amphibious boat tour of the city. The guide told us about that one, now-legendary day in May when the bridge was open to pedestrians. I remember, I told them. I was there. My family was unsurprised, because they know I’ve been fascinated by science and engineering my entire life. The first thing I ever remember wanting to be as a kid was an astronaut—it was the 1970s, the cultural peak of space exploration. By the time I was ten, I wanted to be a nuclear physicist, and this took me all the way through to a degree in engineering physics. Like many women of my generation who went into the field, I had a role model close by, my father. He’d grown up and earned a degree in electrical engineering in a newly independent India before deciding he wanted to see more of the world. In the late 1960s, Canada, like the U.S., was opening its doors to non-European immigrants. My father enrolled in an MBA program at the University of Alberta and when he graduated, he took a job with Ontario Hydro, the public electrical utility for the province. His young family moved to the outskirts of Toronto and he started work at the place where he would eventually spend his entire professional career. A few months later, I was born. And a few months after that, in the next town over, one of the first large-scale nuclear power stations in Canada came online. I grew up on a street that ran down to a sandy beach on Lake Ontario, and when we picnicked and played in the water, the plant was easily visible, eight imposing gray concrete domes and a single massive cylindrical structure on the shoreline. Behind the facility, rows of electrical transmission towers marched along a wide, green right-of-way, first through the nearby suburban housing and then all over the city and region. Best of all, for my tech-obsessed childhood self, they had a visitor center with a nuclear power–themed interactive science museum. In my memory, it’s all buttons and flashing lights, with cutaway models explaining the different systems and a walk-through mock-up of the reactor core. The Pickering Nuclear Generating Station was my local, personal charismatic megastructure. When I had to give a fiveminute speech to my sixth-grade class at school, my topic was obvious: my fellow students got a lecture about the CANDU (CANadian Deuterium Uranium) reactors at our local power station, illustrated with a set of overhead transparencies my dad had brought home from work.

Scientists and engineers have a concept of elegance, which is among the highest praise that can be given to a theory, a proof, or a device. It’s hard to explain exactly what it is, but it incorporates ideas of efficiency or parsimony— accomplishing something with a minimum of effort, energy, or materials. Elegance in engineering often encompasses the surprising and very particular use of the specific resources that are available. Beauty might be part of it, but mostly as something inherent in the design, and the skill and care of its manufacture is part of it too. For example, the graceful curves of suspension bridges, like the Brooklyn Bridge or the Golden Gate, derive from the way that cables are shaped by gravity as they bear the weight of the roadbed below. My local power station probably wouldn’t be described as beautiful, but what was going on inside possessed undeniable engineering elegance.

The reactor systems are carefully designed to produce and control the nuclear reactions that create heat, turning water into the pressurized steam which spins turbines and generates electricity. The CANDU design uses deuterium, an isotope of hydrogen, in the form of naturally occurring heavy water that’s been purified out from ordinary water. It plays a safety-conscious dual role: the heavy water bathes the reactor core, supporting the nuclear reactions and also serving as a coolant. Because the reactor needs the deuterium to remain critical, a leak means that the core will fizzle out instead of overheating. What’s more, the deuterium is so effective at sustaining nuclear fission that the uranium fuel only needs to be lightly enriched. That makes it easier and less dangerous to produce than other reactor fuels, and it’s also much less amenable to being repurposed to make nuclear weapons.

Of course, as a kid I didn’t think about any of the larger issues like limiting the risk of nuclear isotopes falling into the wrong hands or ways to deal with the long-term storage of radioactive waste. But even then, years before I took my first physics or engineering course, I could recognize the elegance and utility of the reactor design and how it made the most of what was available, whether that was locally mined uranium in the reactor core or frigid water from the depths of Lake Ontario for cooling. Today, I recognize this same elegance all over the world and across infrastructural systems, in a giant battery in Wales that’s constructed from two lakes and the mountain between them and in the modular design of a solar plant outside Hyderabad, India. That elegance is a hallmark of infrastructure because these systems are almost always designed around the effective use of resources—above all, the use of energy. For most of human history, access to energy has enabled or limited what’s possible. Harnessing and delivering energy, efficiently and at scale, has long been one of the main drivers for why and how societies have built out collective infrastructural systems.

From How Infrastructure WorksInside the Systems that Shape Our World by Deb Chachra, published on October 17, 2023 by Riverhead Books, an imprint of Penguin Publishing Group, a division of Penguin Random House LLC. Copyright © 2023 by Deb Chachra.