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The Warsaw radio mast was the world's tallest structure until its collapse on 8 August 1991.

The mast

Radio masts and towers

Radio masts and towers are, typically, tall structures designed to support antennas for telecommunications and broadcasting, including television. They are among the tallest man-made structures...

, which was designed by Jan Polak, was tall. Its construction, started in July 1970, was completed on 18 May 1974, and its transmitter entered regular service on 22 July of that year. It was located in Konstantynów, Gąbin

Gabin

Gąbin is a town in Płock County, Masovian Voivodeship, Poland, with 4,230 inhabitants .Between 1974 and 1991 the Warsaw radio mast in Konstantynów, a village belonging to Gąbin commune was the tallest structure on earth. The tower was used to broadcast the programs of Polish Radio throughout...

, Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe . Poland is bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

, and was used by Warsaw Radio-Television (Centrum Radiowo-Telewizyjne) for longwave

Longwave

The longwave radio band is a range of frequencies used for AM broadcasting, which extends from 148.5 to 283.5 kHz. It falls within the low-frequency part of the radio spectrum ....

radio broadcasting on a frequency of 227 kHz before 1 February 1988 and 225 kHz afterwards. Its base, according to Google Earth, was 115.2 metres above sea level. Because a voltage potential of 120 kV existed between the mast and ground, it stood on a 2-metre-high insulator. It operated as a mast radiator

Mast radiator

A mast radiator is a radio mast or tower in which the whole structure works as an antenna. This is commonly used for transmitters operating at VLF, LF and MF, in particular those used for broadcasting.-Design:...

(half wave radiator), so its height was chosen in order to function as a half-wavelength antenna at its broadcasting frequency. The signals from its 2 megawatt transmitters could be received across all of Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...

, North Africa

North Africa

North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa.Geopolitically, the UN definition of Northern Africa includes the following seven countries or territories; Algeria, Egypt, Libya, Morocco, Sudan, Tunisia,Mauritania, and...

and as far away as North America

North America

North America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific...

. Its weight is debated: 380 tonnes, 420 tonnes, 550 tonnes and even 660 tonnes have been cited, probably the result of inaccurate unit conversions by translators

Translation

Translation is the interpreting of the meaning of a text and the subsequent production of an equivalent text, likewise called a "translation," that communicates the same message in another language...

. Polish sources claim 420 tonnes.

Construction

The Warsaw radio mast was a guyed steel lattice mast of equilateral triangular cross section, with a face width of 4.8 m. The vertical steel tubes forming the vertices of the mast had a diameter

Diameter

In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...

of 245 millimetres; the thickness of the walls of these tubes varied between 8 and 34 millimetres depending on height. The mast consisted of 86 elements, each of which had a length of 7.5 metres. The mast had 3 arrays of guy wires, each attached to the mast at 5 levels. Each guy was fixed on a separate anchor block at the ground and was 50 mm in diameter. To prevent the guy wires from interfering with the radio transmissions, the guys were insulated at regular intervals. The weight of guys and insulators used to anchor the mast was 80 metric tons. An elevator and separate protected ladders were installed in the interior of the mast to facilitate access to the various mast components, including the aircraft warning lamps. The elevator had a maximum speed of 0.35 m/s and required 30 minutes for a trip from the bottom of the structure to the top.

In the lower half of the mast, there was a vertical steel tube, attached to the mast's outer structure with large insulators. This tube was grounded at the bottom, and connected electrically to the mast structure at half the total height. This technique works by applying a DC

Direct current

Direct current is the undirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also be through...

ground at a point of minimum radiofrequency voltage, conducting static charge to ground without diminishing the radio energy. Static electrical charge can build up to high values, even at times of no thunderstorm activity, when such tall structures are insulated from ground. Use of this technique provides a better lightning protection than using just a spark gap at the mast feed, which is standard at most mast radiators insulated against ground.

A special overhead radio frequency transmission line

Radio frequency power transmission

Radio frequency power transmission is the transmission of the output power of a transmitter to an antenna. When the antenna is not situated close to the transmitter, special transmission lines are required....

was used to transfer the signal from the transmitter building to the mast. The transmitter building, situated at 52°22'22,9" N, 19°48'25" E, had a volume of 17,000 cubic metres and was approximately 600 metres from the mast. The transmitter consisted of two 1,000 kilowatt units built by Brown Boveri and Cie. An atomic clock

Atomic clock

An atomic clock is a type of clock that uses an atomic resonance frequency standard as its timekeeping element. They are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, and to control the frequency of television...

was used to generate the transmission frequency in order to provide a very accurate, stable signal source which could be used as a frequency standard by anyone within signal range. The station, which had an area of 65 hectares, also had a 76 metre lattice tower of rectangular cross-section close to the transmitter building, at 52°22'23,6" N, 19°48'24,4" E. This tower was used to provide a radio link for programme feeds from the studio.

To supply power to the station a 110kV substation was built. The substation was over-engineered due to the strategic importance of the station as Poland's central transmitter. Although the power consumption of the transmitting station was large (estimated 6,000 kW), the substation was capable of supplying much more than was required.

Six small towers were erected around the periphery of the station's grounds in order to support aircraft warning lamps where the guy ropes were located. They are situated at 52°22'17,4" N, 19°48 9,7" E; 52°21'53,8"N, 19°48'6,3" E; 52°21'57,1"N, 19°47'48" E; 52°21'55,8"N, 19°48'27,6" E; 52°22'6,1" N, 19°48'24,3"E; 52°22'8,1"N, 19°47'54,4" E.

The official name of the facility was Radiofoniczny Ośrodek Nadawczy w Konstantynowie (Radiophonic Transmission Center Konstantynow), Radiowe Centrum Nadawcze w Konstantynowie (Radio Transmission Center Konstantynow) or Warszawska Radiostacja Centralna (WRC) w Gąbinie (Warsaw Central Radio Station Gabin). It broadcast Polskie Radio

Polskie Radio

Polskie Radio Spółka Akcyjna is Poland's public radio network broadcasting corporation.- History :Polskie Radio was founded on August 18, 1925. Regular broadcasting was started on 18 April 1926 in Warsaw. From 1931 broadcasts were transmitted by one of the strongest stations in Europe in Raszyn...

's Program I.

Approximately ten years after completion of the mast, inspections revealed structural damage caused by wind-induced oscillations at the mast, the backstage insulators and the guys. Repair work was very difficult and replacement of the mast by a stronger construction of the same height was considered. However, this was not realized, as a result of Poland's economic situation. In 1988 the mast was repainted, but this could not be done to the desired extent, as there was not enough paint available.

Collapse

On 8 August 1991 at 16:00 UTC a catastrophic failure, caused by an error in exchanging the guy-wire

Guy-wire

A guy-wire or guy-rope is a tensioned cable designed to add stability to structures . One end of the cable is attached to the structure, and the other is anchored to the ground at a distance from the structure's base...

s on the highest stock, led to the collapse of the mast. The mast first bent and then snapped at roughly half its height. A small mobile crane, property of Mostostal Zabrze

Mostostal

Mostostal is a Polish steel construction company with headquarters in Zabrze. The company fabricates and builds a wide range of industrial structures from chemical plants to radio masts....

, was destroyed in the collapse. The helix building

Helix Building

A helix building is a small structure at the base of a longwave or mediumwave radio transmitter. Within, there are capacitors and coils for coupling the signal from the feed cable to the antenna. Active components such as amplifiers are usually not housed in a helix building...

and the transmitter building (including the transmitter devices in it) were not damaged.

An investigating committee determined that blame lay with Mostostal Zabrze, which built and maintained the mast. The construction coordinator and the chief of the Mostostal division that built the mast were accused of causing the collapse. The former was sentenced to 2.5 years in prison

Prison

A prison is a place in which people are physically confined and, usually, deprived of a range of personal freedoms. Other terms are penitentiary, correctional facility, and jail , although in the United States "jail" and "prison" refer to different subtypes of correctional facility...

, the latter to two years.

Since the collapse of the Warsaw radio mast, the tallest structure in Poland has been the FM radio and TV transmission mast at Olsztyn-Pieczewo

FM- and TV-mast Olsztyn-Pieczewo

The FM- and TV-mast Olsztyn-Pieczewo is a 365 metre tall guyed mast for FM and TV situated at Olsztyn-Pieczewo in Poland The FM- and TV-mast Olsztyn-Pieczewo (also known as Maszt RTCN Olsztyn-Pieczewo) is a 365 metre tall guyed mast for FM and TV situated at Olsztyn-Pieczewo in Poland The FM- and...

, measuring 360 metres.

After the collapse, the KVLY-TV mast

KVLY-TV mast

The KVLY-TV mast is a tall television-transmitting mast in Blanchard, Traill County, North Dakota, United States, used by Fargo station KVLY channel 11...

outside Fargo, North Dakota

Fargo, North Dakota

Fargo is the largest city in the U.S. state of North Dakota and the county seat of Cass County. In 2008, its population was estimated at nearly 100,000 and it had an estimated metropolitan population of 195,685...

, USA, regained its title as the world's tallest structure, standing 628.8 m (2,063 ft), until the Burj Dubai

Burj Dubai

Burj Dubai , a supertall skyscraper under construction in Dubai, United Arab Emirates, is the tallest man-made structure ever built, at...

exceeded this height in April 2008.

Replacement

After the collapse of the radio mast at Konstantynów, the Polish broadcasting company used the old Raszyn transmitter

Longwave transmitter Raszyn

The longwave transmitter Raszyn is a longwave broadcasting transmitter near Raszyn, Poland. It was built in 1949. Its radio mast was until 1962 with a height of 335 metres the tallest structure in Europe....

with its 335-metre-high mast near Warsaw

Warsaw

Warsaw is the capital and largest city of Poland. It is located on the Vistula River roughly from both the Baltic Sea coast and the Carpathian Mountains. Its population as of 2009 was estimated at 1,709,781, and the Warsaw metropolitan area at approximately 2,785,000...

, which had been used since 1978 for daytime transmissions of a second Polish broadcasting service programme in the longwave range on the frequency 198 kHz, for transmissions on 225 kHz with a power of 500 kilowatts. It is not possible to transmit from Raszyn on 198 kHz and 225 kHz simultaneously, so the transmissions on the second longwave frequency 198 kHz had to be discontinued until either a second longwave broadcasting transmitting facility was built in Poland or a special frequency switch, which would allow transmissions on both frequencies, was installed at the Raszyn transmitter. The latter, simpler solution would have decreased the effectiveness and reliability of both transmitters and was therefore found unacceptable.

Because the Polish longwave transmitters are of special importance to Polish people abroad, as early as April 1992 the Polish government planned to rebuild the mast at Konstantynów. In September 1995 the Polish government was set to rebuild the mast. Although refurbishment of the old basements, which could be reused, had already started, the rebuilding of the mast was cancelled due to protests by local residents, who claimed that radiation from the mast was a health hazard. While the accuracy of these claims has not been verified, a new site for the transmitter was sought. Several other locations were considered, but due to the continuing resistance of nearby inhabitants (backed by the Solidarity

Solidarity

Solidarity is a Polish trade union federation founded in September 1980 at the Gdańsk Shipyard, and originally led by Lech Wałęsa.Solidarity was the first non-Communist-controlled trade union in a Warsaw Pact country...

trade union

Trade union

A trade union is an organization of workers who have banded together to achieve common goals in key areas, such as working conditions. The trade union, through its leadership, bargains with the employer on behalf of union members and negotiates labor contracts with employers...

), the height of mast designs mast and transmitter range were both highly reduced, and an old military site just southeast of Solec Kujawski

Longwave-transmitter Solec Kujawski

The Longwave transmitter Solec Kujawski is the new longwave broadcasting facility of the Polish broadcasting company for the 225 kHz frequency. Its construction was necessary after the collapse of the Warsaw radio mast on August 8, 1991 and the resistance of the local population to its...

was chosen. There, a new longwave transmission facility was built from 1998 to 1999 with a transmitter of 1200 kW output power for the frequency 225 kHz. This facility, which was inaugurated on September 4, 1999, uses two 289-metre-high grounded upfeed masts 330 metres apart as aerials

Antenna (radio)

An antenna is a transducer designed to transmit or receive electromagnetic waves. In other words, antennas convert electromagnetic waves into electrical currents and vice versa. Antennas are used in systems such as radio and television broadcasting, point-to-point radio communication, wireless...

.

After the inauguration of the transmitter at Solec Kujawski, the transmitter at Raszyn was again used for transmitting on the frequency 198 kHz for the programme Radio Parliament.

Current state

Except for the mast and the radio frequency transmission line that led to it, nearly all components of the facility remain in place, unused and slowly deteriorating.

There are several plans to transform the former transmitter building into a technical museum. In spite of the great historic importance of the site, there is no support for this idea from officials.

Replicas

Eldorado do Sul RBS Radio Mast

Eldorado Do Sul RBS Radio Mast

Eldorado do Sul RBS Radio Mast is the tallest man-made object in Brazil. Eldorado do Sul RBS Radio Mast is used by Rede Brasil Sul Communication Group for medium-wave broadcasting on 720 kHz with 100 kW...

, a mast radiator

Mast radiator

in Eldorado do Sul

Eldorado do Sul

Eldorado do Sul is a municipality in the state of Rio Grande do Sul, Brazil. It is located in the metropolitan area of Porto Alegre, the state's capital and largest city, opposite the capital on the right bank of Guaíba River. Population: 33,098 ....

, Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is a country in South America. It is the fifth largest country by geographical area, occupying nearly half of South America, the fifth most populous country, and the fourth most populous democracy in the world. Bounded by the Atlantic Ocean...