UMO - Unidentified Monitoring Objects

Residents around Symonds Street and Eden Terrace have been asking about what these small white flying-saucer shaped discs are along the pavement that have seemingly “popped-up out of nowhere”.

Fear not, the aliens haven’t landed.

They are actually monitoring prisms installed by the earthlings at Sixense placed around the City Rail Link tunnel route from Mt Eden to Aotea stations.

Our big 130-metre tunnel boring machine (TBM) is currently excavating between the Mt Eden construction site and Karangahape Road. These prisms have been placed on the ground and exterior of buildings to monitor any movement caused by the TBM.

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Pictured: Automatic Total Stations (ATS)

How do they measure movement?

Automatic Total Stations (ATS) have been installed around the project, which point lasers at each prism to measure and monitor any movement. If the ATS detects any movement, then the team are alerted and can take action to prevent any impact on the buildings.