Prague's pneumatic post

The unique system of pneumatic post in Prague has celebrated 120 years of existence.

The Prague Pneumatic Post

Pneumatic post, as it usually happens with most inventions, originated as a result of a mere coincidence. In the 18th Century, Denis Papin (inventor) wanted to transmit energy using compressed air. However, he found out that using compressed air it was possible, under certain conditions, to transport objects, too. There were just a few very simple prerequisites, i.e. a tube, a suitably designed capsule and a compressor to create pressure ratios. Owing to that, the very first line of pneumatic post was launched in London already in 1853. It did not take long and the pneumatic post was built in Prague, too. Martin Žabka, Press Agent of Telefónica O2 Czech Republic, the company in charge of managing the Prague pneumatic post, gave us a better idea of this technological treasure.

What is the history of pneumatic post in the Czech Republic?

The history of the Prague pneumatic post began in 1887. At that time, this line connected the Main Post Office at Jindřišská Street with the Post Office in the Lesser Town (Rott’s House). Later, it was extended to the Prague Castle. Initially, the line served the business purposes only. However, in March 1899, public telegrams and letter post started to be received in this way, too. Today’s city network of pneumatic post was built between 1927 and 1932. The system consists of an exchange and particular lines in a star-like arrangement. In total, the tube is approx. 55 km long and it is concealed approx. one metre under the city surface. From a technical point of view, it is interesting that the tube also runs through three Prague bridges – Legií, Mánesův and Hlávkův.

How does pneumatic post work?

Capsules with letter post move in the tube using the vacuum-cleaner principle. Machine rooms full of powerful blowers pump air either in or out of the tube. On the sender’s part, there is just terminal equipment installed to send or receive capsules. Pressure or negative pressure generated by blowers can make an approx. 4 kg capsule move at 36 km per hour. Capsules can be filled with telegrams, messages, letters and photographs, but also with small construction samples. The speed can be regulated depending on the sensitivity of the content being sent.

What happened to pneumatic post in the 21st century?

Twenty years ago, as many as nine thousand capsules with telegrams and letter post were transported by pneumatic post every month. Unfortunately, the flood of 2002 had a devastating impact on pneumatic post, too. Five of eleven underground machine rooms and a considerable length of the tube were flooded. Telefónica O2 Czech Republic, the company in charge of looking after this technological jewel, is striving to preserve this item of national technical heritage in operation. Until the present day, 70 % of the repair work has been finished.

How can you explain that pneumatic post has survived the age of faxes, e-mail and mobile phones?

There are two reasons why pneumatic post has survived the digital age: speed and accuracy. Whereas with today’s technical means of communication (such as e-mail or fax) the transmission of information is always intermediated and sometimes even distorted, pneumatic post enables to work without distortion and with the original at hand in real time. Moreover, the speed of such transport physically outruns all courier post services. After all, it only took eight minutes to deliver letter post from the exchange at Jindřišská Street to the Prague Castle, for instance. We believe that even in the age of Internet and wireless data transmission, the Prague pneumatic post will remain a beautiful remembrance of the times when capsules full of our history were whizzing under the streets of Prague.

Source: Telefónica O2 Czech Republic, 2002

Documents to download:

Map of Prague's coverage by pneumatic post (JPG)


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