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Invisible Infrastructure: These Underground Systems Keep Cities Running

Hidden infrastructure, buried deep beneath concrete sidewalks and crowds of pedestrians, can yield surprising discoveries about a city’s past. 

Labyrinths of tunnels, pipelines, cables, tracks and transformers keep cities working seamlessly, but are unseen by the masses. Whether created centuries ago or recently renovated, they are responsible for transportation, electricity, water and telecommunications, and are the backbone of modern cities around the globe.

While some infrastructure has been abandoned or has fallen into disrepair, there are countless systems on which millions of residents still depend. From cavernous sewers to the first subway systems, CBRE journeys down into the history and inner workings of the underground structures that help cities thrive. 

Subsurface Transportation

A test run of the first Boston subway at the Park Street Station on Sept. 1, 1897

Many American underground transit systems were constructed during the late 19th and early 20th centuries to deliver services to city residents, and to support rapid urban expansion and development. The country’s first underground subway line opened in Boston in 1897, more than three decades after the introduction of transportation systems in European cities. The line was created to relieve the congestion caused by streetcars above ground.

A few years later, other densely populated cities like New York and Philadelphia built similar systems that combined underground, surface and elevated electrified lines.

Underground transit has since become part of the daily routine of commuters worldwide. The London Underground, or “The Tube,” serves 275 stations throughout London. The New York City subway system has 472 stations spread throughout the five boroughs. Boston accommodates an estimated 390 million rides per year.

While these tunnels are responsible for transporting millions around the world’s largest cities daily, they are virtually undetectable above ground.


An 1871 sectional view of Chicago’s water system

Water running through hollow wooden logs seems crude by today’s standards, but before iron pipes became the norm for water mains, it was the premier method of distributing this resource throughout American communities during the 1800s.

Chicago is often credited as revolutionizing the water system. To prevent waterborne illnesses from sewage flowing into the lake, the city reversed the Chicago River in 1900 to make it flow toward the Mississippi River. It also created an efficient twin-tunnel system, which supplied the city with water that extended two miles out into Lake Michigan.

Now, the Department of Water Management provides just under one billion gallons of water per day to the Windy City and its neighboring suburban communities. Through a sophisticated purification process, water is pressurized and pumped to homes and commercial properties throughout the nation’s third-largest city.

More than 250 million people in the U.S., approximately 90% of the population, get their water from community water systems, which supply water to the same population year-round.

Electric Power

Con Edison at work

Miles of electric cables lie beneath the streets of New York City. Most of the area gets its energy through Con Edison, the power company that has provided New Yorkers with electricity since 1823.

Currently, there are 95,270 miles of underground cables, 266,433 manholes and service boxes and 41,564 underground transformers that keep the city’s lights on.

Before energy reaches power sources in homes, it is sourced from either wind, solar or generating stations. The voltage is then stepped up for transmission over wires, before traveling through power lines and the voltage is stepped down for distribution. Through transformers, the current is stepped again in preparation of its final destination: an outlet.

Con Edison also supplies electricity to the city’s transit system, keeping alive one of the vital threads that has come to define the New York experience. 

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