How Zurich's Digital Archives Ended Up Full of the Same Image Twice — and What the City Is Doing About It

Zurich's municipal digital archive holds hundreds of thousands of images — photographs of the Limmat at flood stage, construction permits filed with the Stadtentwicklung Zürich office, documentation photos from Hardturm stadium's demolition, planning images from the Europaallee redevelopment zone. But a significant share of those images, according to internal reviews conducted by the city's informatik department over the past two years, exist in the system more than once. Sometimes dozens of times.

The problem did not arrive overnight. It is the product of at least fifteen years of institutional fragmentation, software migrations, and the sheer speed at which digital photography replaced film-based documentation in Swiss public administration after roughly 2008. Understanding how it happened matters now because the city is, finally, preparing to act.

A History of Mergers and Migrations

Three separate archive systems were in concurrent use across Zurich's administrative departments as recently as 2019. The Stadtarchiv on Alfred-Escher-Strasse maintained its own cataloguing infrastructure. ETH Zurich's image library, which intersects with city planning databases through joint research programs, ran on different metadata standards. The Amt für Städtebau, responsible for urban development documentation, used a third platform optimised for CAD-adjacent file formats rather than photographic assets.

Each time departments were restructured or software contracts expired, files were exported and reimported. In the process, duplicate detection — if it existed at all — was rarely applied retroactively. A photograph taken at the Münsterhof during a 2011 infrastructure survey might appear under three different filename conventions, tagged to two different departments, with slightly different EXIF timestamps caused by camera clock drift or manual correction.

The UBS-Credit Suisse merger in March 2023 sharpened Zurich's general appetite for administrative rationalisation, not just in banking but across publicly adjacent institutions that had long operated in parallel silos. The city's 2024 digital governance review, which covered all cantonal and municipal informatik systems, flagged media asset duplication as a second-tier priority — significant enough to cost money, not urgent enough to have fixed it yet.

What the Numbers Suggest

The city's informatik office, in documents presented to the Stadtrat in February 2026, estimated that between 18 and 23 percent of images stored in the primary municipal digital asset management system were functional duplicates — identical or near-identical files with different metadata. The review covered approximately 340,000 assets. At current cloud storage contract rates the city pays to its primary provider under a framework agreement negotiated in 2022, the redundant storage alone costs an estimated CHF 80,000 to CHF 120,000 annually, according to the same briefing documents.

The practical consequences go beyond storage costs. When journalists file public records requests under the Öffentlichkeitsprinzip — Switzerland's transparency framework — staff must manually verify which version of an image is the canonical one before release. Researchers at ETH Zurich using historical urban photography for machine learning training sets have reported receiving batches contaminated with duplicates, skewing dataset composition in ways that require time-consuming manual correction.

Deduplication technology is not new. Perceptual hashing tools capable of identifying near-duplicate images even after compression or minor cropping have been commercially available since the early 2010s. The barrier in Zurich's case has been institutional: no single department owned the problem, and no budget line existed to solve it across systems that technically belonged to different administrative units.

That is now changing. The Stadtrat approved a consolidated digital asset management tender process in April 2026, with responses due from vendors by September 1. The selected platform will be required to include automated duplicate detection as a core function, not an optional add-on. Departments including Stadtarchiv, Amt für Städtebau, and the Kommunikationsabteilung are expected to migrate to the new unified system on a rolling schedule between early 2027 and the end of that year.

For anyone who has ever received a folder of Zurich planning photos and wondered why the same image of the Letzigraben appeared four times with four different filenames, the explanation is bureaucratic, not conspiratorial. The fix, when it arrives, will be quiet. But the archive it leaves behind should, at last, reflect the city as it actually is rather than how many times it happened to be saved.