The contemporary silhouette of Rīga is unimaginable without the radio and television tower at Zaķusala. However, this tower distinguishes itself from other standard towers with its individuality and impressiveness. In late 1972, M. Shkud, the chief engineer of the All-Union Planning Institute of the USSR Ministry of Communications, and the chief expert I. Ostrovsky visited Rīga to provide advice on the construction of the tower. Before they arrived a number of sites for the tower had already been chosen — near Bābelītes Lake, at Berģu Hill and Ulbroka. I. Ostrovsky and M. Shkud emphasised that television towers were no longer built solely as technical buildings, but also as tourist attractions with an observation deck and restaurant. They insisted that it should be located in the centre of Rīga, and the most appropriate place, to their minds, was on an island in the centre of the city which they had seen driving from the airport. As it happens, this island was Zaķusala.
The geological findings indicated that the solid bed for supporting the structure was located only 25 metres under ground, therefore making the construction more expensive and complicated, but there was no opportunity to back down — the government had already accepted the building work.
The next stage involved deciding on a design for the tower. The draft design of the building was produced by the Design Institute of the Ministry of Communications of the USSR. The author of the visual design is the Georgian architect K. Nikurdze. At that time very similar reinforced concrete towers were being built in many other places — in Lithuania, Estonia, Moscow and Berlin, with the only difference being the top section. K. Nikurdze considered that the tower should be built from steel, in this way gaining a more impressive look. However, in order to have a choice, five designs were drawn, and models of them were made. The final version of the design was chosen under the leadership of Gunārs Asaris.
Gunārs Asaris requested that the model be altered slightly so that the legs, or supports of the tower were exposed along their whole length. In the original version the silhouette was “thinner”, but it was redesigned to be slightly ‘stockier’ so that the tower could accommodate the antennae for mobile communications,.
General building works were undertaken by the Rīga Industrial Building Trust, using dolomite from Saaremaa, Karelian granite and ironwork that had been prefabricated in Chelyabinsk. The unique metal tower was assembled by the St Petersburg North-western Ironwork Assembly Trust. Metal television towers have their own advantages and disadvantages. It is possible to create various original designs from metal, but it is more expensive than using reinforced concrete, for example, and following construction an anticorrosive treatment is also necessary.
In the early stages of building, the foundations of the tower were laid. 20 reinforced concrete pipes, or hollow-pile foundations, were sunk under each tower support, which rested on a bed of dolomite 24-27 metres below the surface. The hollow-pile foundations were vibrated into the earth with special machinery. The earth was then dug out from the cores and they were filled with concrete.
Metal sections, which were metal boxes two metres high, were delivered via railway from Chelyabinsk to Saulkalne station. These were transported on trailers at night to Zaķusala, which were unloaded with cranes and welded in threes using a rotating positioner located on the ground. In order to guarantee a qualitative welding job, the quality of the welding work was carefully checked. All of the joins were checked by ultrasound. Additionally some of the joins (around 30%) were checked with a portable x-ray machine. As a result of this, it could be guaranteed that there were no defects in the welding. After this, the welded sections, which were comprised of three base sections, were lifted up with a crane and were fixed into place with the help of a positioner, secured with wedges, and then welded from a moveable bridge.
To ensure the stability of the tower during the building phase and the correspondence of the curve of the supports to the line prescribed in the original design, geodesic monitoring was necessary. This was undertaken by the Department of Geodesy of the Rīga Politechnical Institute (currently the Rīga Technical University) and a sub-branch of the Latvian Ministry of Building Works. The head geodesist from the Ostankin complex in Moscow was invited once a year to also take measurements. His results were always identical to the measurements made by both Latvian organisations. The tower was assembled with a high level of precision, and deviations from the design measure only a few millimetres.
Photo: To ensure the stability of the tower and that the curve of the supports conformed to the design, three separate organisations undertook geodetic monitoring. Laser equipment, 20 September 1980.
The settling of the tower’s foundations was monitored during construction. As building work continued, the tower became heavier, and the bed of dolomite underneath buckled evenly: at the end of building work the bend was about 1 centimetre. The difference in the settling of each foundation was no greater than one millimetre. The tower’s structure has been projected to last for 250 years, and this projection includes the possibility of various geological, meteorological and other outside influences, including an earthquake measuring 7.5 on the Richter scale.
Unique engineering solutions were used for the installation of the central antenna. In other towers constructed in Ostankin and elsewhere in the Soviet Union, parts of the entral antenna were assembled in sections, which were later lifted with a crane and then welded on. A totally new and at that time unique method was employed in building the Rīga radio and television station tower — the central antenna was completely welded on the ground and the installation occurred back-to-front: first the spire was assembled and afterwards it was raised using lifting machinery. Each following section was welded on at a special platform located on the ground — that is, the central antenna ‘grew’ from the top down. And this was accomplished when the supports of the tower were only partly assembled, because the tower crane could only assemble the supports to a height of 107 metres. The supports were futher assembled using a crane which was attached to the central antenna.
The middle floors of the tower were also lifted up around the central antenna, first assembled on the ground and then lifted with a lifting mechanism and welded on. The tower’s central antenna rests on the so-called central carcass, which is located 88 metres up. When the last section of the antenna had been assembled and the central carcass had also been assembled underneath, the whole construction, with a mass of around 500 tonnes, was pulled up to a height of 88 metres. This raising was begun on 2 November 1984 and on 13 November the tower reached the planned height of 368 metres.
Next, raising of the panelling for the middle section was a very complicated operation. This panelling is manufactured of Cor-ten, a special weathering steel, and was welded on the ground. Later, these 27 metre high “cards” were raised.
What has changed with the erection of the new Zaķusala television tower? Firstly, the clear reception zone for radio and television around Rīga and central Latvia has doubled in size. Furthermore, the opportunities to install more transmitters and other necessary machinery have significantly increased. In terms of development of the city, the tower is one more successful accent in the city’s panorama.
The geological findings indicated that the solid bed for supporting the structure was located only 25 metres under ground, therefore making the construction more expensive and complicated, but there was no opportunity to back down — the government had already accepted the building work.
The next stage involved deciding on a design for the tower. The draft design of the building was produced by the Design Institute of the Ministry of Communications of the USSR. The author of the visual design is the Georgian architect K. Nikurdze. At that time very similar reinforced concrete towers were being built in many other places — in Lithuania, Estonia, Moscow and Berlin, with the only difference being the top section. K. Nikurdze considered that the tower should be built from steel, in this way gaining a more impressive look. However, in order to have a choice, five designs were drawn, and models of them were made. The final version of the design was chosen under the leadership of Gunārs Asaris.
Gunārs Asaris requested that the model be altered slightly so that the legs, or supports of the tower were exposed along their whole length. In the original version the silhouette was “thinner”, but it was redesigned to be slightly ‘stockier’ so that the tower could accommodate the antennae for mobile communications,.
General building works were undertaken by the Rīga Industrial Building Trust, using dolomite from Saaremaa, Karelian granite and ironwork that had been prefabricated in Chelyabinsk. The unique metal tower was assembled by the St Petersburg North-western Ironwork Assembly Trust. Metal television towers have their own advantages and disadvantages. It is possible to create various original designs from metal, but it is more expensive than using reinforced concrete, for example, and following construction an anticorrosive treatment is also necessary.
In the early stages of building, the foundations of the tower were laid. 20 reinforced concrete pipes, or hollow-pile foundations, were sunk under each tower support, which rested on a bed of dolomite 24-27 metres below the surface. The hollow-pile foundations were vibrated into the earth with special machinery. The earth was then dug out from the cores and they were filled with concrete.
Metal sections, which were metal boxes two metres high, were delivered via railway from Chelyabinsk to Saulkalne station. These were transported on trailers at night to Zaķusala, which were unloaded with cranes and welded in threes using a rotating positioner located on the ground. In order to guarantee a qualitative welding job, the quality of the welding work was carefully checked. All of the joins were checked by ultrasound. Additionally some of the joins (around 30%) were checked with a portable x-ray machine. As a result of this, it could be guaranteed that there were no defects in the welding. After this, the welded sections, which were comprised of three base sections, were lifted up with a crane and were fixed into place with the help of a positioner, secured with wedges, and then welded from a moveable bridge.
To ensure the stability of the tower during the building phase and the correspondence of the curve of the supports to the line prescribed in the original design, geodesic monitoring was necessary. This was undertaken by the Department of Geodesy of the Rīga Politechnical Institute (currently the Rīga Technical University) and a sub-branch of the Latvian Ministry of Building Works. The head geodesist from the Ostankin complex in Moscow was invited once a year to also take measurements. His results were always identical to the measurements made by both Latvian organisations. The tower was assembled with a high level of precision, and deviations from the design measure only a few millimetres.
Photo: To ensure the stability of the tower and that the curve of the supports conformed to the design, three separate organisations undertook geodetic monitoring. Laser equipment, 20 September 1980.
The settling of the tower’s foundations was monitored during construction. As building work continued, the tower became heavier, and the bed of dolomite underneath buckled evenly: at the end of building work the bend was about 1 centimetre. The difference in the settling of each foundation was no greater than one millimetre. The tower’s structure has been projected to last for 250 years, and this projection includes the possibility of various geological, meteorological and other outside influences, including an earthquake measuring 7.5 on the Richter scale.
Unique engineering solutions were used for the installation of the central antenna. In other towers constructed in Ostankin and elsewhere in the Soviet Union, parts of the entral antenna were assembled in sections, which were later lifted with a crane and then welded on. A totally new and at that time unique method was employed in building the Rīga radio and television station tower — the central antenna was completely welded on the ground and the installation occurred back-to-front: first the spire was assembled and afterwards it was raised using lifting machinery. Each following section was welded on at a special platform located on the ground — that is, the central antenna ‘grew’ from the top down. And this was accomplished when the supports of the tower were only partly assembled, because the tower crane could only assemble the supports to a height of 107 metres. The supports were futher assembled using a crane which was attached to the central antenna.
The middle floors of the tower were also lifted up around the central antenna, first assembled on the ground and then lifted with a lifting mechanism and welded on. The tower’s central antenna rests on the so-called central carcass, which is located 88 metres up. When the last section of the antenna had been assembled and the central carcass had also been assembled underneath, the whole construction, with a mass of around 500 tonnes, was pulled up to a height of 88 metres. This raising was begun on 2 November 1984 and on 13 November the tower reached the planned height of 368 metres.
Next, raising of the panelling for the middle section was a very complicated operation. This panelling is manufactured of Cor-ten, a special weathering steel, and was welded on the ground. Later, these 27 metre high “cards” were raised.
What has changed with the erection of the new Zaķusala television tower? Firstly, the clear reception zone for radio and television around Rīga and central Latvia has doubled in size. Furthermore, the opportunities to install more transmitters and other necessary machinery have significantly increased. In terms of development of the city, the tower is one more successful accent in the city’s panorama.