User:Tallinn TV Tower
The Tallinn TV Tower was constructed for the broadcast of national television programmes. It is situated in Pirita, a suburb of Tallinn. With its 314 metres, the TV Tower is the tallest building in Tallinn. The TV Tower was constructed in time for the sailing regatta held in Tallinn as part of the Summer Olympic Games in 1980. The cornerstone was laid on 30 September or some five days earlier (25 September) 1975. The tower was officially opened on 11 July 1980. The viewing platform at a height of 170 metres was open to the public until 26 November 2007, when it was closed for renovation. Having been repaired, the tower began receiving visitors again on 5 April 2012. The tower’s geographical coordinates are 59° 28′ 16″ N, 24° 53′ 15″ E (map). The architects were David Basiladze and Juri Sinis, the engineers – Vladimir Obydov and Yevgeny Ignatov. The construction work was supervised by Aleksander Ehala. The structure comprises of a 190-metre reinforced-concrete tower and a 124-metre metal mast on top of it. Under the tower is a two-storey building with equipment rooms, entrance halls and a conference centre. The diameter of the tower at its base is 15.2 metres and the wall thickness is 50 cm. The diameter of the tower from 140 metres upwards is 8.2 metres. A total of 10,000 m3 of concrete and 1,900 tons of steel were used in the TV Tower construction.
Contents • 1 Tallinn TV Tower's structural features • 2 Construction work • 3 Incidents at the TV Tower • 4 Technical specifications • 5 Images • 6 Sources • 7 References • 8 External links
Tallinn TV Tower’s structural features
Aerial view of the TV Tower.
32 building enterprises participated in the construction of the Tallinn TV Tower. The TV Tower design was created by specialists of the State Design Institute of the Ministry of Communications in Moscow. The chief engineer was Yevgeny Ignatov, the chief designer was Vladimir Obydov and the architects were Juri Sinis and David Basiladze.
The team faced two serious initial challenges: to choose a suitable tower structure and select the best location for it. The structure was selected with confidence: a freely supported base part from reinforced concrete and steel upper part serving as the antenna, with a total height of 314 metres. The internal space of such a TV tower made from reinforced concrete is sufficient for installation of all the necessary equipment and addition of a viewing platform with a restaurant accessed via a high-speed lift. The height of the tower is such that it is capable of transmitting excellent radio and television signals to distances of up to 90 kilometres in ideal weather conditions.
Several factors were taken into account when the location was being selected: the required distance from densely populated urban areas to ensure proper signal reception; geological features of the local soil; distance from the airport; impact on Tallinn’s skyline. The chosen spot was 8 kilometres from the city centre, in a rest and recreation zone not far from the botanical garden and a motor sports club. Location height above sea level: 23 metres. The TV Tower dominates the surrounding landscape and affects the local architecture. The TV Tower is clearly visible from the city and from the sea.
The structure of the tower can be divided into three sections: the foundation, the tower itself from reinforced concrete (190 m) and the steel antenna (124 m). From 150–182 metres the tower contains a superstructure that is 38 metres in diameter, housing the viewing platform, the restaurant and the equipment room for commercial radio stations. The two-storey building that surrounds the base of the tower is also 38 metres in diameter and contains technical and auxiliary facilities.
The foundation slab made from reinforced concrete is 38 metres in diameter, 2.5 metres thick and buried 8.5 metres below ground level. This slab supports the tower from reinforced concrete that is 15.2 metres in diameter at the base and only 8.2 metres in diameter at a height of 180 metres. The wall thickness in the lower part is 500 mm and in the upper part it is 350 mm, this is to ensure tower stability even in strong storm conditions. Before 1967 all tall structures had been built in Estonia in compliance with the safety requirements applicable to structures situated in areas with the second wind strength level. After the storm in 1967, with the wind speed reaching 42 metres per second, the TV tower was designed in compliance with the fourth wind strength level requirements.
The mass total of the tower is over 20,000 tons[3]. The centre of gravity of the structure is in the base of the tower, which is why it could not fall over even if the foundation slab was on the surface of the ground.
The general contractor was the Tallinn Construction Trust and the subcontractors were the Reinforced Concrete Construction Trust, the Metal Structures Trust and the Radio Construction Trust. The work was commissioned by the TV Tower Construction Directorate of the Ministry of Communications of the Estonian SSR, with Vootele Tõsine as its director at the time.
Construction work Several new technical solutions were implemented during the construction of the TV Tower. The reinforced-concrete tower itself was assembled using the sliding mold method. The concrete mold was installed at a height of 2.5 metres, then the armature was inserted and the concrete was poured. After that the concrete form was shifted upwards, narrowed to the new diameter value and the new section of reinforced concrete was created. Today you can still see the rings resulting from this concreting process at 2.5 metre intervals on the tower. The concrete was poured continuously for 8 months, with the tower gradually rising above the landscape. The builders used the M-400 concrete based on oil shale ash and Portland cement. This concrete had been developed by the scientists at the Tallinn Polytechnical Institute under the supervision of Professor Verner Kikas. The concrete was designed to withstand 300 frost resistance cycles. Subsequent inspections have revealed that the strength of this concrete is even higher than stipulated. The antenna part of the structure is made from steel cylinders. The metal antenna was installed using the ejection method. At first a smaller-diameter cylinder was lifted to the necessary spot, then over it was placed a larger-diameter cylinder and the smaller cylinder was pushed up through it with blocks and winches. The assembly was completed by attaching to each cylinder the television and ultra short-wave transmitter vibrators. The upper metal framework weighing over 120 tons was assembled on the ground around the base of the tower and then raised to 170 metres. From start to finish all building work was supervised by foreman Aleksander Ehala and team master Väino Saar. They often had to solve extremely complicated problems and the designers always agreed with their solutions. The TV Tower is a sophisticated structure and it is therefore regularly checked for geodetic compliance: foundation settling, vertical deviation, condition of reinforced concrete and metal components, other parameters of the tower. The allowed swerve of the top of the TV Tower due to wind is 1.5 metres, of the viewing platform – 90 cm. Besides winds, the tower is affected by solar heat, resulting in the top “drawing” a peculiar curve. The steel part, from 190 m to 260 m, has a lift for two persons and hatches for access to the external platforms for the purpose of inspection and repairs of the antenna equipment. In the tower below the antenna section there is also a staircase with 1,050 steps, all the way from the basement to a height of 190 metres.
Important dates: • 30 September 1975 – laying of the cornerstone • April 1976 – completion of the foundation installation work • May 1977 – construction of the reinforced-concrete tower, 17,500 tons of concrete poured and 330 km of armature inserted • February 1978 – the lift shaft is made in the 52 reinforced-concrete blocks of the tower • April 1978 – assembly of the metal antenna part commences • 13 June 1978 – the tower reaches the intended height of 314 metres • 30 October 1978 – the frame of the upper structure raised into place • December 1978 – installation of 16 supports in the upper structure, the tower now looks exactly as designed • 20 December 1979 – first transmission from the tower • 11 July 1980 – opening of the Tallinn TV Tower • November 2007 – the Tallinn TV Tower is closed for visitors as it lacked a sufficient number of evacuation routes and exits • 4 April 2012 – the renovated Tallinn TV Tower welcomes new visitors
Incidents at the TV Tower In April 1980 Väino Saar prevented a major construction accident. A welder’s negligence had caused the cables in the tower shaft to catch fire. The draught was strong because the structure acted like a giant chimney. The fire thus crept quickly up the tower from the point of origin on the 5th storey. Väino Saar managed to outrace the conflagration and cut off the cables on the 23rd storey, thus preventing the fire from reaching the metal part of the tower. Had the antenna structure been subjected to heat from the fire, it might have collapsed. The fire damage was liquidated within one month. Over the decades the antenna equipment on the TV Tower underwent a major overhaul. Due to the introduction of the FM waveband the radio antennas were rebuilt. A 12-metre pipe-shaped grooved antenna for the 45th television channel transmitter was installed at the very tip of the tower. This antenna also resulted in an accident at the tower. Jüri Makarov was a prominent local businessman who created a new television station, Tipp TV, and that included installation on the TV Tower of an Italian-made transmitter for the 45th television channel. The corresponding antenna, a 12-metre pipe, had been purchased in the USA and Makarov decided to install it with the aid of a helicopter. Commissioned all the way from St. Petersburg, the helicopter landed on the square next to the tower. Preparations began for the antenna installation. The helicopter successfully removed an old radio antenna from the top of the tower. In the early morning on 19 May 1994 the helicopter took off with the new antenna that was to be inserted in the slot on top of the tower. The decisive moment arrived: the helicopter with the antenna suspended under it on a cable was hovering over the top of the tower, with manoeuvres made to push the end of the antenna into its slot. The wind was disruptive, its force reaching 8. The antenna touched the tower, the pilots assumed that it went into the slot and they released the cable. In a couple of seconds the antenna came tumbling down the side of the tower. It hit the restaurant roof and grazed the railing. The roof of the viewing platform and its windows shattered. The antenna itself broke as well. A new antenna was sent in later and the specialists successfully installed it under the supervision of leading engineer Vitali Lonkin. Väino Saar oversaw the repairs of the restaurant roof.
Technical specifications • Tower height: 314 m • Viewing platform height: 170 m • Height of base above sea level: 24 m • Total weight: >25 000 t • Viewing platform diameter: 38 m • Foundation depth: 8.5 m • Foundation slab thickness: 2.5 m • Permitted deviation from wind at tower top: 1.5 m • Permitted deviation from wind at viewing platform level: 90 cm • The concrete section (from the basement up to the point at which the metal section begins) has 1,050 steps • From the 13th-18th storeys (they are 20 metres high) the tower only contains the lift shafts and the fire escape staircase. As of February 2010, the Tallinn TV Tower transmits the following radio and TV stations:
Antenna
FM transmitters:
• Vikerraadio,
• Raadio 2,
• Raadio 4,
• Klassikaraadio,
• Raadio Tallinn,
• Raadio 7,
• Maania,
• Energy,
• Sky,
• Sky+,
• Russkoye Radio,
• Uuno,
• Dinamit FM,
• Raadio 100,
• U-Pop,
• Kuku
TV transmitters:
• DTV (Digital television)
GSM transmitters:
• EMT
• Elisa
• Tele 2