Zurich's Duplicate Image Problem: The Key Decisions Ahead

The city of Zurich's central digital archive, maintained by the Stadtarchiv on Alfred-Escher-Strasse, is holding tens of thousands of duplicate images—redundant files accumulated over more than a decade of uncoordinated digitisation projects across municipal departments. A review launched in the first quarter of 2026 has put the problem squarely on the agenda of the city's IT steering committee, and the decisions made in the coming months will determine how Zurich manages its visual records for years to come.

The timing matters. Zurich is mid-way through a broader overhaul of its public data infrastructure, tied in part to a CHF 47 million digital transformation programme approved by the Gemeinderat in late 2024. Duplicate image files are not a trivial nuisance—they consume server capacity, slow search and retrieval, introduce version-control errors, and complicate compliance with Switzerland's revised Federal Act on Data Protection, which came fully into force in September 2023. For a city already wrestling with constrained administrative budgets and a housing crisis that has stretched departmental priorities thin, the question of who owns this problem is pointed.

How the Backlog Built Up

The duplication crisis traces back to the early 2010s, when individual departments—from Tiefbauamt, which manages roads and civil engineering, to the Amt für Städtebau overseeing urban planning near Hardturm and Altstetten—began digitising legacy photographs and construction records independently, without a shared naming protocol or central deposition point. Files were uploaded to department-level servers, then again to shared network drives, and in several cases again to cloud storage after the city signed a framework agreement with a European provider in 2019. By some internal estimates, as many as 30 percent of stored image files in certain departmental archives are duplicates or near-duplicates—a figure that has drawn pointed questions at recent sessions of the Stadtrat's digital oversight group.

ETH Zurich's Data Science Lab has been in preliminary contact with the Stadtarchiv about applying machine-learning deduplication tools that researchers there have developed for large scientific image repositories. No formal contract exists yet, but the conversations reflect how acutely the city's own technical staff recognise they lack the specialist capacity to tackle the backlog in-house. The Stadtarchiv currently employs 34 full-time equivalent staff; budget documents from the 2025 annual report show no dedicated line for image-data remediation.

What the City Must Decide Now

Three decisions are bearing down fast. First, the IT steering committee must settle on a deduplication standard before the next server-capacity review in September 2026—without one, contracted storage costs, currently benchmarked against Swiss data-centre rates in the Zurich metropolitan region, will continue rising. Second, the city must determine whether the ETH partnership moves to a formal pilot, and if so, which department's archive goes first—Tiefbauamt's construction photograph collection, estimated at over 800,000 image files, is the largest single repository and therefore the most logical starting point, though also the most politically sensitive given active infrastructure litigation. Third, Stadtarchiv leadership must propose whether duplicate-image governance falls under existing Stadtarchiv statutes or requires a new administrative directive—a question with direct implications for who bears liability when a deleted file turns out to have been the only copy of a legally relevant document.

The public will not vote directly on any of this; Swiss direct democracy rarely reaches the level of municipal IT policy. But the Gemeinderat's finance committee is scheduled to review discretionary digital spending in October, and advocacy groups focused on open government—including the Zurich chapter of Digitale Gesellschaft, based in the city centre—have begun tracking the file-management issue as a transparency concern. If the city contracts external vendors without a public tender, that too will draw scrutiny.

For residents in Zurich-West or anyone who has tried to pull planning documents through the city's online portal and hit broken links or mismatched file versions, the stakes are practical rather than abstract. The coming weeks will test whether Zurich's administration can move from diagnosis to action before the September deadline—or defer again into the next budget cycle.