The 99% Invisible City Read online

  Different countries have their own national, regional, and local conventions, too, which can be more or less official. In a BBC News article, journalist Laurence Cawley scratches the surface of London’s underground utilities with some local examples, including ones that illustrate how intuitive certain codes can be. A number next to a D often indicates depth, for instance. For electrical lines, H/V means high voltage, L/Fdenotes low voltage, and S/L stands for street lights. For gas lines, HP refers to high pressure, MP to medium pressure, and LP to low pressure. Some markings are harder to understand at first glance, like a looping infinity symbol used to indicate the beginning or end of a proposed project area—a counterintuitive use of a character normally applied to things without beginnings or ends. Biodegradable paints are typically employed to create the variously colored letters and symbols sprayed by specialists onto the streets and sidewalks of our cities. These odd hieroglyphics are then either erased in the course of excavations or simply left to fade over time, slowly making room for newer, more vibrant squiggles when the next project rolls around. While they last, though, such markings provide essential information to diggers as well as ephemeral windows for the rest of us into the complex systems running right beneath our feet.

  Initialed Impressions

  Sidewalk Markings

  As the country’s original capital and the backdrop for many key moments of American history, the city of Philadelphia is lousy with important era-defining monuments and plaques, whose grandeur can make subtler and less dramatic markers easy to miss. Amid the many statues standing in squares and tablets affixed to buildings are a series of enigmatic plaques embedded in sidewalks. The etched or embossed messages on these metal plaques read like abstract spatial koans or urban poems advising pedestrians that “Space within building lines not dedicated” or “Property behind this plaque not dedicated.”

  In property law, dedicating means giving over to another party—the public, for example. The wording on these plaques varies, but the basic message of these so-called easement markers is the same: you pedestrians are welcome to walk here for now, but just a heads-up—this is actually private property. To define such areas, long thin rectangular plaques are often arrayed to form a dashed demarcation line along the boundary of the property while right-angled variations are used to define the corners.

  In a 2016 PlanPhilly article, reporter Jim Saksa explains that “the plaques are used when the property lines don’t align with the building’s physical dimensions or the dimensions of any sort of fencing, landscaping or other improvements that would clearly mark a boundary between the public right-of-way and private property.” In other words, a passerby might assume a property line ends at a fence or hedge or the edge of a building when the actual property line might run through a sidewalk instead.

  Easement laws can give people limited rights to cross other people’s land but can also allow for different forms of adverse possession. As Saksa explains the concept, if someone uses a piece of property “blatantly, consistently and exclusively for a long, statutorily set amount of time—21 years in Pennsylvania—then they own it.” In the case of these prescriptive easements in Philadelphia: if private owners fail to explicitly mark out their territory, someone could eventually argue they have forfeited ownership. That’s why you’ll see these markers embedded in sidewalks both there and in other cities. The plaques ensure that the public knows that this particular patch of sidewalk belongs to the property owner even if they allow the public to walk on it for now.

  Such plaques only scratch the proverbial surface of the sidewalk etchings that comprise a cityscape. There are, of course, the ubiquitous informal markings made less than legally by ordinary citizens, like so-and-so + so-and-so with a heart around it scratched into drying concrete sidewalks. But there are formal marks, too, and not just for easements. Among the semi-permanent declarations of love, you’ll find elegant signatures in many cities that were left by the construction companies that laid the sidewalk.

  In California’s Bay Area, sidewalks in cities like Oakland feature stamps or plaques dating back to the early 1900s when concrete began to take off as a cheap and robust alternative to brick or board walkways. Many sidewalk stamps that remain date back to the 1920s through the postwar era of rapid urban expansion. Some are wrapped with decorative borders and include construction dates, addresses, phone numbers, and even union numbers. A curious individual could write down the stamped union number, go to the union office, and look up the name of the individual who smoothed out that patch of concrete fifty years before.

  In places like Chicago, these markers are ubiquitous and detailed because they are required to be under municipal law: “Before the top or finishing of concrete walks has set, the contractor or person building the walk shall place in such walk in front of each lot or parcel of property a stamp or plate giving plainly the name and address of the contractor or person building the walk and the year in which the work was done.” In turn, these markings end up becoming physical archives of urban development, telling the histories of cities and city-building businesses, and outlining tales of neighborhood construction and expansion. In the sidewalks of Berkeley, California, there are markings representing the evolution of a family business over decades. A Paul Schnoor stamp might show a date of 1908 while over in a newer neighborhood, you’ll find a Schnoor & Sons stamp, presumably a rebranding that took place when the next generation began working for their dad. If you encounter an even more recent construction project, you can actually find a Schnoor Bros. mark that recalls the era after dad retired and the boys took over.

  In some cases, concrete installers have effectively turned sidewalks into signage, too, naming streets at intersections, lending them additional wayfinding functions. This hasn’t always gone well for cities, though. Back in 1909, an article in the Calgary Herald titled “Calgary Can’t Spell” lamented prominent misspellings like Linclon and Secound Avenue etched into the sidewalks. The piece pressed for the prevention of “any further occurrences of the disgraceful spelling with which the names of our streets and avenues are unfadingly imprinted in the walks of stone,” admonishing that “workmanship such as this might be tolerated in ramshackle frontier towns, but cannot be in Calgary.” In response, municipal workers were instructed to tear out the offending slabs and thus spare this proud Albertan city further embarrassment. In San Diego and other cities, old sidewalk stamps (at least ones that are spelled right) are actively protected—construction workers are supposed to work around them wherever possible when tearing up and replacing sidewalks so these small pieces of urban history can be preserved.

  These days, many cities no longer require markers on new sections of sidewalk. Some bureaucratic killjoys even mandate that contractors get a permit to sign their work, and they significantly limit the size of signature stamps—after all, these represent free and durable advertising that can last for decades or longer. But more important for us, sidewalk markings tell a rich story about who made our built environment, down to the individual worker who got down on his knees to make a piece of land smooth and walkable for generations of people. You can learn so much from reading sidewalk markings—especially when they’re spelled right.

  Planned Failure

  Breakaway Posts

  Posts that hold up signs, street lights, and utility lines need to be strong and durable enough to withstand winds, storms, tsunamis, and earthquakes. Every so often, though, these same posts are called upon to do something crucial but fundamentally at odds with their everyday function: they need to break easily on impact. If hit by a fast-moving vehicle, posts need to come apart in just the right way in order to reduce damage and save lives. Engineers have spent a lot of time attempting to resolve this apparent paradox.

  One of the ways to get robust posts to break properly is called a “slip base” system. Instead of using a single continuous post, a slip base approach joins two separate posts close to ground level using a connector plate. This joint allows the p
air to break apart at an intended juncture. It works basically like this: a lower post is put in the ground, then an upper post is attached to it using breakaway bolts. These bolts are made to fracture or dislodge when the post gets hit hard enough, so the upper post gets knocked over while the lower post passes safely under the moving vehicle. When everything works as designed, such posts can also help slow down a vehicle and minimize damage. Subsequent infrastructure repair becomes easier as well—in many cases, a new upper post can simply be bolted onto the undamaged base post below it, which requires less material and work. The critical plate-to-plate connections underpinning slip systems can be obvious to the naked eye or tucked away under plate covers.

  The connector plates of inclined slip bases take this basic engineering design a step further by being tilted at an angle relative to the ground and optimized for hits from an assumed direction of impact. Instead of simply sheering sideways, posts are actually launched up into the air on impact, ideally landing behind the car that hit them. In slow-motion crash test videos, signs arc up, twirl overhead, then land on the road surface once the vehicle has passed beneath it. The downside is that if the post is hit from an unexpected direction it might not break away at all.

  Straight or angled slip bases can work in isolation, but they can also be paired with hinged upper connections that help preserve infrastructure and save lives. The telephone lines running along the tops of utility poles can in some cases help hold up a pole even if a vehicle crashes into it. Instead of falling over (potentially onto a vehicle or into a lane of traffic), a telephone pole can be designed to break off at its base and then swing up and out of the way before coming to a stop and hanging in place while the cables linking it to neighboring poles hold it up temporarily.

  Slip bases and hinge systems aside, different kinds of breakaway posts can be found all over the built environment. Many of the world’s stop signs are supported by joined metal posts. Their joints work differently, but the basic idea is the same: two post sections are connected in a way that makes it easier for them to break apart. An in-ground post is matched with an aboveground insert post that is designed to bend or break on impact. Once you spot them, it becomes hard to unsee these common solutions to the perpetual problem of cars crashing into signs.

  People generally tend to think that the development of safer cars is what protects them in their vehicles, which is true to an extent. Quality wheels provide traction, sturdy frames resist damage, seat belts and airbags keep passengers secured and cushioned, and safety glass is designed to break into less harmful shards. In the end, though, car design and construction are just a few variables within a larger safety equation. The engineering of things people crash into plays a less conspicuous but critical role in our safety as well.

  A Little Safer

  Emergency Boxes

  Even though they are generally positioned at eye level directly adjacent to entryways and are adorned with reflective red stripes, Knox Boxes are easy to overlook. Like Kleenex, Dumpster, or the once-trademarked escalator, Knox Box is the common brand name associated with a generic thing: in this case, the rapid entry access boxes affixed to all kinds of urban architecture. When disaster strikes, these urban safes go from being functionally invisible to highly essential in an instant.

  Seconds count in an emergency, so getting inside a building quickly and safely is critical. Knox Boxes offer a simple solution: when emergency personnel respond to a call and arrive on site, they use a master key or code to unlock a rapid entry access box and retrieve its contents. Inside a typical box is another key or code for accessing that specific building. So firefighters essentially have a skeleton key that opens all of the boxes in their area. With that one key, they can effectively gain entry to the huge array of buildings they are charged to protect, including apartments, stores, office complexes, art museums, and more.

  There are various types of Knox Boxes. Some boxes work like small safes, providing access to a single key or set of building keys. There are also more advanced ones that flip open to reveal control panels with more complex functionality. Some have switches that allow responders to disable power or gas lines or sprinkler systems in cases of false alarms.

  In the absence of at least a basic access box, firefighters and paramedics would have to wait to be let in or physically break into buildings, leading to injuries and damaged property. In light of potential broken-down doors, busted-up windows, or burned-down buildings, adding a small box to the outside of a building seems like a smart option.

  From a security perspective, these access boxes may sound like a perfect opportunity for a burglar to go on a robbery spree, but building owners and key users are aware of the risks and take precautions. Some building managers also tie their boxes to larger security alarm systems that will trigger when anyone accesses them. As for the master keys that open the boxes, some fire departments employ tracking functionality to avoid losing them or letting them fall into the wrong hands. Though cities and businesses don’t always agree on the necessity of having Knox Boxes, many people feel that the rewards outweigh the risks, so you can spot these clever little boxes everywhere.

  Fake facade in front of a subway exhaust opening in Paris

  Camouflage

  There are beautiful pieces of civic infrastructure that feed the soul—from ancient ornate aqueducts to structurally expressive modern bridges. Generally speaking, though, most infrastructure doesn’t get this royal treatment. Rather than making an exhaust port or an electrical substation into a flamboyant display of modern engineering, we often do the next best thing: we hide them. The camouflaging of everything from oil derricks to cell phone towers can be so devious and varied, it can sometimes be difficult to distinguish between what’s real and what isn’t.

  Thornton’s Scent Bottle

  Stink Pipes

  Initially envisioned as an open public space by the aptly named architect Francis Greenway, Sydney’s Hyde Park is Australia’s oldest park. In the late 1700s, this open space had been primarily used by locals to graze animals and gather firewood. Over time, the area became a place where children played and cricket matches were held. In the 1850s—as the city and neighborhood around it continued to evolve—grass, trees, running water, and monuments were added. The park became increasingly formal and grand, a place for political orations and official gatherings for visiting royalty. One of its most outstanding features from that era is a towering obelisk.

  Inspired by Cleopatra’s Needles—a series of ancient Egyptian relics now in London, Paris, and New York—the Hyde Park Obelisk was unveiled in 1857 under the tenure of Sydney mayor George Thornton. The roughly fifty-foot-tall monument sits on a twenty-foot-tall sandstone base; its tapered sides are wrapped in sphinxes and serpents. Locals were so enamored with their revamped park and its exotic centerpiece that after the mayor gave his speech at the unveiling “he was carried on the shoulders of stalwart men” to a nearby hotel, according to one newspaper account.

  As the fervor died down, however, people began to notice a strong, unpleasant smell wafting off this otherwise impressive monument, which led it to become known by another name: Thornton’s Scent Bottle. The tower’s noxious emissions were not accidental but a product of its actual design intent. Like many other seemingly innocuous sculptures in cities around the world, this obelisk served two primary purposes: one aesthetic and one functional. It was not just an impressive display of cosmopolitan splendor but a means to vent gases from the city’s underground sewer system.

  The idea of using a grand monument to ventilate a sewer may seem strange, but the city’s sewage system was a new technology for Australia at the time. On the functional side, engineers had developed two basic types of sewer vents—educt and induct. The induct drew in air while the educt allowed lighter gases back out. Pressure, odor, and disease had to be addressed in the system, so they were addressed in style, starting with the Hyde Park Obelisk’s eductive design. The resulting obelisk is both infrastructure and landm
ark. Since its erection, the obelisk has been the subject of several modifications and repairs, but it has mostly been preserved in its original form.

  The precedent of the Hyde Park Obelisk inspired other early ornate brick ventilation shafts around Sydney. In other major cities, sewage exhaust designs can be a bit more of a mixed bag—many so-called stink pipes around London are relatively utilitarian affairs. Some are dressed up a bit to look like monuments or lampposts, but most could be mistaken for rusted flagpoles. The Sydney obelisk, meanwhile, is still in use today, though its function has shifted slightly. It is now used as a vent for stormwater runoff rather than the smelly city sewer system. It’s now a monument in its own right, too, having been added to the New South Wales State Heritage Register in 2002. In the end, this faux monument to Cleopatra became a real monument to modern cities and the way they have adapted to new kinds of infrastructure.

  Exhaustive Outlets

  Fake Facades

  The controversial Ehekarussell sculpture in Nuremberg, Germany, features sets of larger-than-life bronze figures arrayed around a low pool that depict the ups and downs of domestic married life. From young love to the death of a spouse, the vivid scenes on this “marriage merry-go-round” capture a lifetime of joys and sorrows, passions and pains, in explicit ways that many local residents were not excited to confront on leisurely strolls through the historic city. The dramatic sculpture serves an even more notable purpose beyond aesthetics, though; it’s placed strategically to conceal an exhaust port for one of the city’s U-Bahn lines. Completed in the 1980s, this installation is a relatively recent example in a long tradition of subway ventilation camouflage, infrastructure that runs the gamut from small and sculptural to huge and architectural.