Warsaw radio mast

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The Warsaw radio mast in Konstantynów
The Warsaw radio mast in Konstantynów
View from a distance
View from a distance

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

Warsaw Radio Mast, which was designed by Jan Polak, was 646.38 metres (2,120 feet) tall. Its construction started in July 1970, and it was completed on May 18, 1974, and the transmitter which used it entered regular service on July 22 of the same year. It was located in Konstantynów, Poland (52°22′14″N, 19°48′23″ECoordinates: 52°22′14″N, 19°48′23″E), and was used by Warsaw Radio-Television (Centrum Radiowo-Telewizyjne) for longwave radio broadcasting on a frequency of 227 kHz (before February 1, 1988) and 225 kHz (after). The mast was insulated from the ground for a voltage of 120 kV so stood on a 2 metre high insulator. It operated as a mast radiator, so its height was chosen in order to function as a half-wavelength antenna for its broadcasting frequency. The signals from its 2 megawatt transmitters could be received across all of Europe, North Africa and even in North America. Its weight is debated: 380 tonnes, 420 tonnes, 550 tonnes and even 660 tonnes have been cited, probably the result of inaccurate conversion of units by translators. Polish sources claim 420 metric tonnes.

Contents

[edit] Construction

Desription of transmitter Gabin and Warsaw Radio Mast in Polish language
Desription of transmitter Gabin and Warsaw Radio Mast in Polish language

The Warsaw radio mast was a guyed steel lattice mast with an equilateral triangular cross section with side lengths of 4.8 m. The vertical steel tubes forming the vertices of the mast had a diameter 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. In order to combat the problems associated with build up of static electrical charge, the guy wires were insulated at regular intervals. The weight of guys and insulators used for anchoring 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 to the top of the construction.

In the lower half of the mast, there was a vertical steel tube, which was fixed with large insulators at the mast construction. This tube was grounded and fixed directly to the mast structure at half height. It formed, together with the lower mast, half a circuit, which blocked the transmitter signal from flowing to the ground, but allowed conduction of static electric charges to ground, which can reach large values even at times when there is no thunderstorm on such tall structures if they are insulated from the ground.

A special overhead radio frequency transmission line was used to transfer the signal from the transmitter building to the mast. The transmitter building had a volume of 17,000 cubic metres and was approximately 600 metres from the mast. The transmitter consisted of two 1000 kilowatt units built by Brown Boveri and Cie. An atomic clock was used to generate the transmission frequency in order to provide a very accurate stable signal source which could be used as a standard frequency by anyone within signal range. The station, which had an area of 65 hectares, also contained a 76 metre tall lattice tower of rectangular cross-section. 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 6000 kW), the substation was capable of supplying much more than was required.

Small towers were erected around the periphery of the station grounds in order to support aircraft warning lamps where the guy ropes were located.[1].

The official name of the facility was Radiofoniczny Ośrodek Nadawczy w Konstantynowie, Radiowe Centrum Nadawcze w Konstantynowie or Warszawska Radiostacja Centralna (WRC) w Gąbinie. The radio program was called "Program Pierwszy Polskiego Radia", "Program I PR" or unofficially "Jedynka".

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.

[edit] Collapse

On August 8, 1991 at 16:00 UTC the mast collapsed due to an error in exchanging the guys on the highest stock of the mast. Officially, the workers had left the area well before the mast collapsed, so no one was killed or injured. Some unconfirmed sources claim there were 3 fatalities and 12 people injured.[2]. It is possible that this was confused with the collapse of WLBT Tower on October 23, 1997, when 3 people were killed.

The mistakes in the exchange of guys were confirmed by Jan Polak, the main constructor of the mast.[3]PDF The mast first bent and then snapped at roughly half of its height. The top went straight to the ground near the base, followed by the lower half which leaned and fell in an unconfirmed direction. At the collapse a small mobile crane, property of Mostostal Zabrze, was destroyed[4]. The helix building and the transmitter building (including the transmitter devices in it) were not damaged in the collapse.

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 catastrophe. The former was sentenced to 2.5 years, the latter to 2 years.

Since the collapse of the Warsaw radio mast, the tallest construction in Poland is the transmission mast for FM-radio and TV at Olsztyn-Pieczewo with a height of 360 metres (coordinates: 53°45′13″N, 20°30′57″E).

After the collapse, the KVLY-TV mast outside Fargo, North Dakota, USA, regained the title as the world's tallest structure, standing 628.8 m (2,063 feet). This may be exceeded during the next decade with the building of the Burj Dubai, or a possible solar updraft tower in Australia that will stand 1000 m (3280 ft), but the latter's financial viability remains unclear.

[edit] Replacement

After the collapse of the radio mast at Konstantynów, the Polish broadcasting company used the old transmitter of Raszyn with its 335 metre high mast near Warsaw, which had been used since 1978 during the day for the transmission of a second programme of the Polish broadcasting service 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 long wave frequency 198 kHz had to be discontinued until either a second long wave 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 unacceptable.

Because the Polish long wave 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 rebuild of the mast had to be cancelled due to protests of people living in the surrounding area, who claimed that radiation from the mast was a health hazard. While the veracity of these claims has not been verified, a new site for the transmitter was sought. It was found in the form of an old military area just south-east of Solec Kujawski, where from 1998 to 1999 a new longwave transmission facility with a transmitter of 1200 kW HF-outpower for the frequency 225 kHz was built. This facility, which was inaugurated on September 4, 1999, uses as aerials two grounded, upfeed masts, which are 289 metres tall and 330 metres apart from each other.

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.

[edit] Current state of site

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

From the mast itself, the basement, the anchor blocks and the hole in the ground, at which the insulated mounted steel tube in the mast ended, are still there [5].

[edit] In popular culture

The Warsaw radio mast was mentioned in Guinness World Records as the world's tallest structure. It was also shown on local postage stamps [6].

[edit] Trivia

The mast was unique in the following aspects:

  • In contrast to guyed masts in the USA with lower heights, which are carriers of antennas for FM- and TV-broadcasting, Warsaw Radio Mast was a mast radiator insulated against the ground.
  • In all Europe outside the area of former Soviet Union there is no architectural structure with a comparable height. The tallest structure in Europe outside the area of former Soviet Union, the longwave radio mast Hellissandur with a height of 412 metres is much smaller. Even the Ostankino Tower, Europe's largest free-standing structure, was surpassed by this mast by more than 100 metres.
  • It was the only half wave radiator ever realized for longwave

[edit] See also

[edit] External links

[edit] References

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