An explosion in Harlem this week has brought renewed focus to the city’s crumbling structures – from gas mains to bridges

The explosion that killed at least seven people in the East Harlem neighbourhood of New York this week has been attributed to a gas leak. While investigators have yet to confirm that conclusion, it has brought new focus to New York’s crumbling infrastructure: a gas main in the street outside is 127 years old.

The day before the tragedy, the Center for an Urban Future issued its latest report, setting out in great detail the scale of the infrastructure problem in America’s biggest city. The report, Caution Ahead, points out that many waters mains are over 100 years old, average gas mains are over 56 years old and subways are pushing 100.

Bridges

According to the report, 11% of the 162 bridges in New York City are more than 100 years old.

The Manhattan Bridge was built between 1901 and 1912. While the bridge was being built footpaths were used by workers to reach certain areas and heights. Photograph: Library of Congress

Each day, about 2.7m cars drive over the 47 bridges rated “fracture critical” (a designation engineers use for bridges that have little structural redundancy, making them prone to failure and collapse) and “structurally deficient”.

Facebook Twitter Pinterest The approach to the Triborough Bridge in the 1970s. Photograph: public domain

Fracture critical bridges not only suffer from significant distress, but according to engineers, if a single span, beam or joint of such a bridge fails, the whole thing could come tumbling down.

Facebook Twitter Pinterest A recent view of the Manhattan Bridge. Photograph: public domain

Subway

The subway system stretches along 659 track miles. The first underground line of the subway opened on 27 October 1904, almost 35 years after the opening of the first elevated line in New York City.

Facebook Twitter Pinterest With a shovel, Edward Everett McCall, chairman of the New York Public Service Commission breaks ground for a subway in New York City in 1914. Photograph: Flickr Commons

While the system has cleaned up its act considerably since the 1980s, when graffiti and breakdowns were the norm, the ageing signalling system is in dire need of attention. Of the system’s 728 miles of mainline signals, 37% have exceeded their 50-year useful life, meaning trains move slower and maintenance workers are forced to build their own replacement parts because manufacturers no longer make them.

Facebook Twitter Pinterest The subways remained covered in graffiti for much of the 1970s and 1980s. Photograph: Erik Calonius / US National Archives

Water mains

Facebook Twitter Pinterest New York City Deputy Police Commissioner John A Leach, right, watching agents pour liquor into a sewer following a raid during the height of prohibition. This was only a few years after many of the city’s water mains were installed. Photograph: Library of Congress

15% of the city’s 6,800 miles of water mains are over 100 years old. There have been more than 400 water main breaks in New York City in all but one year since 1998. In 2013, there were 403.Customers are losing about a quarter of water to leaks between the reservoir and the faucet – double that of the industry standard. To stave off water main breaks, experts have suggested the city follow a 100-year replacement cycle – meaning replacing roughly 68 miles of water mains every year. The city has failed to reach this target a single time over the last decade.

2014 has already seen a major water main break on 13th Street in Manhattan, which flooded the streets and nearby subways. In 2013, a similar incident paralyzed subways at 23rd street, as shown in the MTA’s video below.

Gas mains

Cat on a Hot Tin Roof came out in 1958, making it 56 years old – the same age as the average New York gas main.



60% of Con Edison gas mains are made of unprotected steel or cast iron, an outmoded and leak-prone material. More than 2% of the gas Con Edison sends to customers every year never makes it to its final destination – largely because of leaks.

Facebook Twitter Pinterest Cat on a Hot Tin Roof movie poster 1958. Photograph: Public Domain

On Wednesday, an explosion caused the swift and entire collapse of two buildings in East Harlem, leaving at least seven people dead and more than 60 injured. Mayor Bill de Blasio later said the explosion was caused by a gas leak and that utility company Con Edison was in the process of shutting off all gas lines into the building.



Firefighters battle a fire after a building collapses in the East Harlem neighborhood of New York. Photograph: John Minchillo/AP

Roads



There are 19,000 lane miles of roads and highways in New York. The department of transportation has deemed 30.4% of city roads in “fair” or “poor” condition – up from 15.7% in 2000. Roughly 43% of all roads in Manhattan are considered substandard, followed by Staten Island (40%), the Bronx (34 %), Queens (31 %) and Brooklyn (28 %)

The cobblestone streets of yore: garbage carts protected by police during a strike on 13 November 1911. Photograph: Library of Congress

Facebook Twitter Pinterest The age of modernity: a pothole on a new york city street remained trash-filled for two weeks in 2008. Photograph: public domain

JFK airport

JFK’s Air Cargo Facilities are approximately 40 years old. 63% of these facilities are unfit for modern screening, storage and distribution.

The Beatles arrived at John F Kennedy airport in 1964 – 10 years before some of the present cargo facilities were built. Photograph: Library of Congress

The report warns that if infrastructural vulnerabilities are left unchecked, “they could wreak havoc on the city’s economy and quality of life.” Bringing physical assets up to scratch will require a nearly unprecedented investment, coming to a total cost of $47.3bn over the next four to five years – a challenge harder to meet in these times of federal budget cutbacks.

While tragedies are rare, countless disruptions and malfunctions are directly caused by the aging systems. Modernizing the aging assets won’t be cheap, but inaction is no longer an option.

• This article was amended on 14 March 2014 to correct the caption on the second photo. The original stated the bridge in the photo was the Manhattan Bridge and not the Triborough Bridge. This has now been corrected.