How Zurich's Digital Archives Ended Up Full of Duplicate Images — and What's Being Done About It

Zurich's municipal digital infrastructure is carrying tens of thousands of duplicate images across departmental servers, a structural problem that has quietly compounded since the city accelerated its digitisation drive around 2018 and that administrators are now under pressure to fix. The issue surfaced prominently in recent budget discussions at Stadthaus, where IT procurement officers flagged redundant storage costs as a line item that had grown difficult to justify given the city's tight fiscal planning horizon through 2028.

The timing matters for reasons that extend beyond housekeeping. With the city's landmark smart-city programme, Smart City Zürich, entering its next operational phase and ETH Zurich's ongoing collaboration with municipal departments on data governance, there is now institutional appetite — and external scrutiny — to get the underlying asset infrastructure in order before new systems are layered on top of a disorganised foundation.

How the Duplication Problem Grew

The roots of the problem trace back to decisions made when individual departments digitised their own workflows independently rather than under any unified standard. The Stadtarchiv Zürich, which manages the city's official records on Alfred-Escher-Strasse, ingested photographic collections from multiple legacy sources simultaneously. The Amt für Städtebau, responsible for urban planning documentation across neighbourhoods from Altstetten to Schwamendingen, built its own image repositories for construction permit files. Neither system spoke consistently to the other.

Each time a departmental merge, software migration, or hardware refresh occurred, images were typically copied rather than moved, and metadata was inconsistently tagged. A single aerial photograph of the Limmatquai taken for one planning study might exist in four separate folders across two departments, each with a slightly different filename convention and resolution export. Multiply that pattern across a decade of digitisation activity and the redundancy accumulates fast.

The problem was not unique to Zurich — cities from Hamburg to Vienna have confronted analogous digital-asset sprawl — but Zurich's comparatively high per-gigabyte enterprise storage costs made the financial case harder to ignore. Municipal IT contracts reviewed during the 2025 budget cycle showed storage expenditure for administrative image assets had risen by a measurable proportion year-on-year since 2020, according to documents presented to the Gemeinderat's finance committee.

Clearing the Backlog

The practical response has unfolded in stages. In 2024, the city's central IT unit, Organisation und Informatik (OIZ), piloted a deduplication audit using hash-matching software across a subset of Amt für Städtebau files. The pilot identified a significant share of files as exact or near-exact duplicates. OIZ has since extended the methodology to additional departments, with a full cross-departmental pass planned for completion by the end of the third quarter of 2026.

ETH Zurich's Data and Service Center for the Humanities, based on campus near Rämistrasse, has been involved in developing metadata standards that would prevent the problem recurring. The principle is straightforward: a canonical master record for each image asset, with departments linking to it rather than saving local copies. Implementation is the harder part, requiring staff retraining, workflow adjustments, and contractual updates with several external vendors who supply images for public communications.

For residents and businesses that interact with city services — anyone submitting a building application in Oerlikon, say, or accessing historical maps through the Stadtarchiv's public portal — the immediate practical impact of the cleanup should be modest but tangible: faster load times on document portals, more reliable search results, and fewer instances of conflicting image versions appearing in official publications.

The deeper lesson city officials are drawing from the episode is about governance structure rather than technology. Smart City Zürich's next programme agreement, expected to be finalised before the end of 2026, is expected to include explicit data-asset management standards as a baseline requirement for any new digital project funded through the programme. The goal is to make duplicate proliferation an exception that triggers a review rather than a default outcome of bureaucratic habit.