on polcevera, the thompson center, and moral choice in preservation

Several regular correspondents wrote last week to note the controlled demolition of the remaining spans of the Ponte Morandi in Genoa, and to wonder about its replacement.

As noted earlier, the collapse of the bridge last August was largely attributable to lack of maintenance, the inability to easily monitor the health of the embedded steel in its stays, and a design that offered little redundancy. The question of what should replace the span is a provocative one–at the moment a scheme by Renzo Piano for a simple, understated viaduct with none of the heroic towers or muscular stays of the original is planned:


All well and good–the design is understated, seems reasonably efficient, and predominantly in concrete, meaning that it will have the multiple load paths and robustness to weather the lack of attention that infrastructure in Italy (and, for that matter, in the U.S.) receives these days. But a couple of readers, knowing of my fondness for Morandi and this bridge in particular, wonder about the lack of reference to the original, which was a true Genovese landmark. I used the bridge all the time to talk about basic cable stayed principles in classes, since it had a simple, direct form that did a great job of explaining itself.

But. That simplicity clearly came with a price. Piano’s design relies on bending and the hyper static nature of continuous beams–difficult to explain how it carries itself over those piers without some serious math, or at least some complex diagrams showing negative moments canceling one another out, etc. That complexity adds redundancy to the span, though–there are many possible load paths and ways to distribute the loads of the deck among the piers, while in the original viaduct there was a single path, through the diagonal stays and into the A-frame towers. Disrupt that one path and you lose the whole bridge.

That makes for a great teaching example, but–and this is purely hindsight–a dangerous design that relies on the health of a single, largely invisible element–the steel strands encased in concrete that formed the diagonal stays. This is the structural equivalent of putting too many eggs in one basket, and while that basket may be evocative, beautiful, expressive–all the things I look for in a teaching example–it was an approach that came with dire consequences.

Do we memorialize that? It’s hard to imagine residents of Polcevera, the neighborhood underneath the bridge, warming to such a reminder of last August’s disaster, or to the legacy of deferred maintenance (the conscience-salving term of art for ‘negligence’) that has put thousands of miles of viaducts and bridges all over the world at risk for similar collapses. There’s an argument, I think, that if as a society we’re so manifestly unwilling to invest in the upkeep and care of such beautiful–but delicate–structures, then maybe we really shouldn’t build them.

Just to further poke the bear, the current debate over the fate of the James Thompson Center in Chicago strikes me as a related question. The State of Illinois, its longtime occupant, is putting the building up for sale, and most current options involve a wholesale demolition, which has preservationists up in arms about the loss of a controversial, though important, piece of post-modernism. I’m on record as being no fan of the building, but the questions around Piano’s memory-free viaduct resonates with my reasons for being ambivalent about the Thompson Center fight. The Thompson Center was an energy disaster when it opened, requiring 35% more energy to cool it during summer than anticipated, a figure blamed initially on the failure of an ice-making system, but over time resting squarely on its 17-story, southeast-facing, single-glazed atrium. The “$172-million oven” failed to attract much interest when the State initially floated the idea of selling it in 2015 in part because of its high heating and cooling costs.

How energetically do we fight to save a building that promises low energy efficiency, inefficient space planning, and ongoing maintenance issues as its curtain wall continues to leak and granite panels fall off of their supports? As our energy situation gets more and more dire, I’d argue that fighting to save the 1986 Thompson Center will look, to future generations, like restoring a 1986 Jaguar XJS to all of its 13-mpg glory and gifting it to them, along with its five-figure annual garage bills and its dated aesthetics. Yes, it may be seen as a classic someday, but aesthetics are tied to how cars or buildings serve our needs, too. I doubt the XJS is going to garner more fans as gasoline prices go inexorably up, and I doubt that the Thompson Center would, if we lost it, be our generations’ Chicago Stock Exchange–a building whose loss reflects poorly on the architect and developers of the early 1970s.

Chicago Federal Building/Postoffice. Henry Ives Cobb, 1905.

I’m guessing, instead, that the loss of the Thompson Center would be more like our generation’s Federal Building/Postoffice–which Helmut Jahn himself cited as inspiration for the Thompson Center’s atrium. The building was supposed to be Henry Ives Cobb’s masterpiece, but it turned out to be an unmitigated disaster. Cobb had taken a position as Supervising Architect for the Treasury Department after receiving the commission, and in splitting his time between Chicago and Washington he failed to keep in touch with the Postoffice project. It went over budget and several years over its planned schedule, but even worse were the inherent flaws in the design itself. While mail handling and retail operations required vast, open spaces, Cobb insisted on a rigid, Beaux-Arts plan, with a frankly useless dome and a greek-cross layout that divided the full-block site into four quadrants, each of them far too small for the functions that Cobb then crammed into them. The dome itself worked as a giant chimney, drawing air through the public areas that sucked doors shut and scattered paper throughout the building. Worse, the dome’s stack effect pulled foul air from the horse tunnels that brought mail to the structure’s basement, meaning that the entire building stunk of manure, especially on hot summer days. The Postmaster General of the United States began planning for its replacement days after its opening (a more effective structure that was built in two phases and now straddles the Congress Expressway). Cobb never built on this scale again, and took up a second career as a founder and leader of (wait for it) the American Arbitration Society.

Had the postoffice survived into the present era, I suspect plans to demolish it would meet with stiff resistance–both for its age and its importance to the daily life of the Loop, it would have made a strong argument for preservation, under today’s criteria. But it still would have been a remarkably lousy building–Cobb’s lack of supervision meant that it was built with largely inferior granite, the subject of lawsuits and accusations of corruption that dogged him and the contractor long after the building’s completion. For better or worse, and I’d argue for better, the building came down in the early 1960s to make way for Mies van der Rohe’s Federal Center:

That’s the replacement postoffice in front–a clear span volume that does the job that Cobb’s building could never do. Is Chicago worse off for having demolished what was, by all accounts, an historic but fatally flawed building? Diehard postmodernists would disagree, but I find it hard to argue that the 1905 Postoffice would have been better for the city than the public plaza and rigorous but subtle architecture of the Mies buildings. Certainly the Post Office is better off.

We can’t save everything, and when the preservation community argues for everything we tend, I think, to dilute any moral authority we have for making the case for buildings worth saving. No, we can’t know what will look like it should have been saved a generation or two from now–this is the Stock Exchange argument. But that doesn’t make it possible to take the fundamentalist position of going to the barricades for every proposed demolition. The fight to preserve, in the Thompson Center’s case, a building whose main argument for preservation is that it’s an exemplar of a particular style seems to me like a ‘moral holiday.’ It’s easy to see the headline, pull out the letter-to-the-editor template, and express outrage at yet another loss to the city’s historic fabric.

The more difficult choice is to acknowledge that there are moral and ethical consequences to preservation, too, and not being absolutely sure of what future generations will value or be able to use doesn’t give us the right to simply throw up our hands. We’re perfectly capable of making a reasonably well-informed decision about a building that in this case, is likely to be as welcome to our children and grandchildren as that Jaguar XJS. What if, instead, we fought hard to make sure that whatever replaces the Thompson Center, or the Polcevera Viaduct, is objectively better–safer, more energy-efficient, more durable? That may not win us many preservation merit badges, but it would be a step toward assuring that the cities around these contested sites evolved in ways that those future generations would still find helpful.

“insulation with vision” up on JSTOR

U.S. Patent 2,235,680, “Multiple Glass Sheet Glazing Unit and Method of Making the Same.”  Issued to Haven and John Hopfield in March, 1941.

Happy to report that a key “reconnaissance paper” on the history of insulated glazing has just been published in the Association for Preservation Technology Bulletin, and is up on JSTOR. (Behind the subscriber paywall, but hit me up if you want a digital copy). “Insulation with Vision” tracks the difficult development of the technique–the glass ‘sandwich’ around an evacuated or gas-filled void that increases the insulation value of otherwise highly thermally transmissive glazing.

Abstruse? A bit, but also important. Without this technology, the glass curtain wall couldn’t have been deployed to the extent that it was in the 1950s and beyond through today. Less striking but perhaps more important in terms of scale, the picture window–a signature feature of suburban housing in the era–couldn’t have happened either.

The story’s a good one–it includes a Milwaukee trolley ride, a biscuit factory in Oakland, Cranbrook, the original John Hancock Building in Boston, and Chicago’s Keck and Keck. It’s one of a handful of deep dives into the ‘enabling technologies’ of the postwar skyscraper that are forming the setup to the new project on postwar Chicago skyscrapers…

Penguins play a role in the story of insulated glazing, too. Penguins! [Folder  11, Box no. 45, MSS-066, Libbey-Owens-Ford Glass Company Records, University of Toledo Libraries, Ward. M. Canaday Center Manuscript Collection].

big and tall 2019

Arch 517 – Evan, Jeff, Miguel from Miguel b on Vimeo.

Late on this one, but wanted to do justice to a fine semester of Big and Tall, my seminar course in building history. Students take on one building or structure and, over the course of the semester while I’m lecturing, they analyze its balancing of assembly and performance, looking for clues to the designers’ intentions, constraints, and solutions. The final results are more and more digital these days, though students have the option still of building physical models. As you can see, though, building in pixel-space gives them the opportunity to explore the role of time and sequence, which allows more nuanced understanding of the construction processes. (Video by Evan Harrison, Jeffrey Klynsma, and Miguel Bardaji Izard).

Lane Pralle, Digitally-fabricated model of isostatic slab from Pier Luigi Nervi’s Palazzo Lavoro
Tarun Bhatia and Tyler Vincent, sequencing model of Notre Dame de Paris

 Obhishek Mandal and Michael Stanley, Comparison between New Caledonia Cultural Center, Renzo Piano Building Workshop, and local building traditions.
 Eric Heckman, Nathan Sands, and Casey White, Re-creation of anthropomorphic Firth of Forth Bridge demonstration.
Eric Heckman, Nathan Sands, and Casey White, digitally-fabricated structural model of Firth of Forth Bridge.
Matthew Cramer and Alec Hoppe, articulated structural model of Zarzuela Racecourse grandstand, Eduardo Torroja