The National Geodetic Survey purchased several "G-Towers" in the 1970s from Sweden. Originally designed for measuring distances, the Survey soon found that they were not the most appropriate tools to gain height when measuring angles.
After a trip to Sweden in 1975 to learn about "G-Towers," the National Geodetic Survey (NGS) purchased about eight of these towers. The towers were triangular, telescoping, and went up to a height of 100 feet. This type of tower was tested at NGS's Corbin, Virginia facility, and then further tested in 1976 on a survey project with Bilby Towers in New York.
The Swedish designers intended the towers to be used for measuring distances. NGS's attempt to use them for observing angles on the New York test project did not work well due to the twist of the towers and the vibration from the necessary guy wires. Further usage of G-Towers was very limited, if at all, after the New York project.
- Tower shown: G-Tower
- Approximate dates of use: 1975
- Average heights: Up to 100 feet
- Materials of construction: Steel/metal
- Unique features: Telescoping; designed more for measuring distances than angles.