Pneumatic Systems: The Unseen Side of NYC

Pneumatic Systems: The Unseen Side of NYC

You may not realize it, but pneumatic systems are a part of your every day life in New York City. A method of movement that takes advantage of the principles associated with air pressure, pneumatic systems have been a part of NYC’s infrastructure for decades, assisting with everything from transporting mail to removing trash. Here is a closer look at the history of pneumatic systems in New York and how they are used.

Transporting Mail

New York City’s postal service began using a pneumatic system in 1897 to assist with the transport of mail between its 23 post offices. The 27-mile-long pneumatic tube was made from cast iron and was buried four to six feet underground, forming a loop that stretched from City Hall in the south to Harlem in the north. The system also had an extension that ran to Brooklyn.

The transport of the mail took place in two-foot-long canisters capable of holding 500 letters each. Through the system of air compressors and blowers, the pressurized tubes could move the containers at speeds of up to 30 miles per hour. New Yorkers were so fascinated by the system when it was put in place that they sent a copy of the U.S. Constitution, a bible and even a live cat through the system. Fortunately, the cat was not harmed in the demonstration.

At its peak of operation, approximately one-third of all first-class mail processed through the city’s main post office was passed through the pneumatic system. That came to about 95,000 letters per day. With the federal government being required to make annual rental payments for the system of $17,0000 per mile, however, the postal service ultimately stopped using the pneumatic delivery system in 1953.

Propelling a Railcar

Inspired by a pneumatic mail system that he saw in London, Alfred Ely Beach patented his Beach Pneumatic Transit system in 1865. Using his own money, he built a prototype tunnel that could create enough pressure to propel a railcar. The one-block-long tunnel featured high-powered fans on either end to create the necessary pressure.

While the system never made it beyond the prototype stage, people did travel on the line. Despite the proof that the concept worked, the city decided to explore elevated railways for public transportation instead.

Trash Removal

Since 1975, Roosevelt Island has used a pneumatic system to collect and remove the trash of its 12,000 residents. With the island consisting mostly of dense multi-family buildings, trash collection is completed by throwing the waste into trash chutes that lead into a trash room within each building. A few times per day, the sanitation department trips the trap doors located within these trash rooms, which then brings the trash to an underground system of 20-inch wide piles. The waste is then whisked way at 60 miles per hour to a centralized facility called the automated vacuum assisted collection system (AVACS).

The AVACS system, which is located on the north side of the island, contains centrifugal turbines capable of spinning at high speeds. This creates a vacuum that sucks the trash into a compactor that crushes the waste to one-twentieth its size. It is then trucked off of the island.