Levelling-benchmarks

• Subheading: Use of Sille.space, City of Tallinn

Levelling-benchmarks Tallinn, Estonia 

Case Background
The complementary use of satellite radar interferometry (InSAR) with traditional systems has been successfully applied in projects worldwide. The wide coverage and high density of information, provided remotely by advanced InSAR techniques, is not achievable with in-situ instrumentation. The historical satellite data provides a ground deformation baseline (e.g. identification of pre-existing ground movement).

Objectives
Commissioned by the city-planning office’s engineering department:
1. To validate and check the stability of the city’s official height network, on which key infrastructures such as buildings, roads, bridges, tunnels, water supply, sewers, and electrical grids are built.
2. To pinpoint height benchmarks that should be re-leveled
3. Highlight areas that need to be focused on and where benchmarks need re-leveling

Tallinn (Europe capital city) - Vertical movements 2016-2021

Leveling-benchmarks  summary
• Manual (terrestrial leveling) and Sille.Space measurements matched 90%
• The focus was to capture the 10% of the official height network that needs re-leveling by engineers. Sille.Space quickly highlighted the areas that need to be focused on and where the leveling benchmarks were outside of the required thresholds.
• Cost saving of a $340,000 if the 116 leveling benchmarks were to be reviewed manually
• Sille.Space has opened a completely new capability to the city’s engineering department and city development office because of Sille.Space is faster, more cost-efficient, and provides frequent historical information. Efficiently monitors a wide area for millimeter movements minimizing survey times and costs
• Regular monitoring of operational infrastructure supports the maintenance program, helping identify possible structural weaknesses or damage, and providing an early warning of possible accelerations in deformation.

Jaanis Lill – Head of Geodesy and Land Management:

“Sille.Space allows the Geodesy and Land Management Unit in Tallinn’s Urban Planning Department to make well-informed decisions about which parts of the height benchmarks need re-leveling. It also enables us to avoid unnecessary and large-scale engineering tasks which in turn also helps to more accurately schedule tasks ahead. – This allows us to save hundreds of thousands in costs.”