New York's Invisible Construction

When urban infrastructure deteriorates, "invisible construction" technologies can simplify maintenance and minimize disruption.

Just 150 years ago, New York City depended on as many as 20,000 pigs to clean its streets by consuming everything in sight. At that time, a combination of raw sewage and waste, rampant disease and overpopulation, made it one of the most unsanitary, crowded and unsightly cities in the world. As the 20th century approached, technology began to transform and improve city life through innovations in sanitation, construction and transportation:

In 1842, aqueducts began bringing water to New York from up to 50 miles (80 kilometres) away. By 1937, the system reached over 100 miles (160 kilometres) to the north and east.
The Brooklyn Bridge was completed in 1883, the longest bridge in the world in its day.
Beginning in the late 1850s, the elevator made skyscrapers possible and, by the turn of the century, the use of steel girders had allowed dozens of buildings to reach heights of 50 stories.
By 1913, New York had become a leader in rapid transit, carrying over 800 million passengers on over 120 miles (192 kilometres) of track.

New York City's massive and comprehensive infrastructure has served its residents well. However, its leaders are aware that a well-managed, sustainable urban environment is not simply a function of structural integrity or physical mass. It also requires regular maintenance and repair. New York City's infrastructure is in crisis. Over half its bridges are rated structurally deficient. By 2010, one-fifth of all sewers will be past their useful life. In 20 years, the same will be true for one-quarter of all water mains, whose break rate per mile is expected to double between now and 2030 (one every five miles).

Lack of continued maintenance also threatens New York City's 76 waterway bridges; 12,000 miles of water and sewer mains, the electricity, gas, and steam lines; and 700 miles of subway most of which is buried beneath the 6,200 miles of city streets.

These systems are falling apart after decades of neglect because there are no easy maintenance strategies. Until very recently, "sustainability" was not a driving factor for designers of these systems.

Nineteenth century planners had the foresight to build extensive networks for a capacity of service that residents still rely on today, but did not see beyond the expected life span of the systems themselves.

For safety and aesthetic reasons, the original designers hid the "innards" of the city, but in doing so they complicated access for repair and replacement. Reconstruction in New York City, as in other dense urban areas, is disruptive to residents, businesses and visitors, as well as inconvenient and expensive to perform. There have been limited incentives to perform adequate preventive maintenance over time. The default strategy has been to wait for failure. Once failure has occurred, it is usually considered adequate to repair the existing system as quickly as possible. However, this creates a never-ending cycle with little potential for advancing beyond technologies developed at the turn of the century.

In New York, demand for less obtrusive technologies has given rise to the concept of "invisible construction." This means technologies that minimize negative effects of (re)construction on a system's users and neighbors. For example, "trenchless" technologies allow hundreds of feet of pipelines (sewers and water mains) to be serviced from two access points. Municipalities are using this method all over the world to keep from digging up every road and street to upgrade their subsurface systems. Prefabricated bridge deck systems allow entire bridges to be constructed off site and floated in place, facilitating on-site construction which is now completed in days rather than months. Perhaps entire temporary roadways could be constructed and "floated" to maintain traffic flow during major highway renovations adjacent to waterways.

These invisible construction techniques, as well as new technologies to muffle noise and collect dust, help to minimize gridlock, noise, duration, closures and other headaches typically associated with construction. They are also making it easier to save city infrastructure systems without rendering them useless in the process.

Burying infrastructure can escalate construction costs beyond reasonable means. Recently, attitudes toward infrastructure have begun to change. Architects and engineers are developing a new design vocabulary in which elements of infrastructure are exposed, even celebrated. Out of this shift are coming technologies and design solutions that are providing adequate levels of service and simultaneously simplifying preventive maintenance.

Elements of infrastructure that remain concealed upon reconstruction should begin to include plans for access without disruption. The return on this initial investment will be massive reductions in maintenance for the life of the system.

When systems deteriorate, we must approach their replacement as a catalyst for improvement. As new systems are designed and built, they can incorporate the necessary features to provide future maintenance without disruption. As time passes, invisible construction will become more necessary in New York, and in other cities that have employed similar public works techniques. Invisible construction techniques are a portent of innovations in infrastructure design yet to come, allowing urban people and systems to continue functioning while the lifelines of their city are maintained.

Michael Fishman is an urban and architectural planner with The Sam Schwartz Company in New York City. This article was adapted and abridged from one appearing in the Autumn, 1998 issue of Urban Age Magazine.

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