Zurich's Duplicate Image Problem: What Happens Next and the Key Decisions Ahead

Zurich's municipal digital infrastructure is sitting on a problem that has quietly ballooned over the past three years. The city's central document management platform, used by departments from the Stadtentwicklung office on Amtshaus I to the building permit registry in Oerlikon, has accumulated an estimated tens of thousands of duplicate image files — redundant scans, re-uploaded photographs, and mirrored planning documents that are consuming server capacity and complicating records searches. The Stadtrat is now expected to decide before the end of the third quarter of 2026 how aggressively to clean up the archive, and who bears responsibility for doing it.

The timing matters. Zurich is mid-cycle on a broader digitisation push launched under the Smart City Zürich programme, which earmarked CHF 28 million across its 2023–2027 funding period for infrastructure modernisation. Redundant data isn't merely an aesthetic bureaucratic nuisance — it inflates storage costs, slows search tools that planners and citizens rely on for Grundbuch and Baubewilligung lookups, and creates legal ambiguity when multiple versions of a planning image appear to be official. With housing pressure at its most acute in at least a decade and the Wohnungsnot crisis pushing vacancy rates in the city below 0.1 percent as of the most recent cantonal survey, the speed and legibility of the planning process carries real stakes.

Where the Bottlenecks Are Concentrated

The duplication problem is not evenly distributed. City IT officials have identified the Amt für Städtebau, based at Lindenhofstrasse 19, and the Tiefbauamt as the two departments with the heaviest image-file redundancy, largely because both underwent rapid partial digitisation between 2020 and 2022 without a unified deduplication protocol. Files from physical scans were often uploaded by multiple staff members working remotely during the pandemic period, producing near-identical copies catalogued under different metadata tags. The ETH Zürich spin-off Deduce AG, which has consulted on similar municipal archive projects in Basel-Stadt and Geneva, has been in preliminary discussions with the city — though no contract has been publicly confirmed or announced.

The technical fix is not especially complex. Standard deduplication algorithms can identify pixel-identical or near-identical images with high confidence. The harder question is governance: which department signs off on deletion, how long must flagged files be held in a quarantine archive before permanent removal, and what happens when two departments each believe their version of a planning image is the authoritative one. Swiss administrative law places strict obligations on record retention, and the cantonal Staatsarchiv on Winterthurerstrasse 170 would need to be consulted on any disposal schedule that touches documents with a statutory retention requirement.

The Decisions That Will Define the Outcome

Three choices now sit on the table. First, the city must decide whether to proceed with a fully automated deduplication sweep or require human review for any image tied to an active planning case — a distinction that could mean the difference between a three-month project and a two-year one. Second, there is the question of cost allocation: if the duplication originated in part from poor coordination between departments, which Direktionen absorb the remediation bill. Third, and most consequential for ordinary Zurich residents, is whether the cleaned archive becomes fully publicly searchable via the existing Stadt Zürich open-data portal, or remains an internal tool.

That last point is where civic groups are paying attention. The transparency organisation Öffentlichkeitsgesetz.ch has previously pushed cantonal and municipal authorities on proactive data disclosure, and the duplicate-image episode gives advocates a concrete example of why poorly maintained archives reduce effective public access. A public portal accessible from anywhere — including from the Stadtbibliothek Zürich on Limmatquai or a neighbourhood Quartierzentrum in Wiedikon — would let residents track planning applications affecting their streets without filing formal information requests.

The Stadtrat's working group is due to publish its preliminary recommendations by September 2026. Whatever framework emerges will almost certainly be tested immediately: the city has more than 1,200 active building applications in the pipeline as of mid-year, many of them linked to the densification of districts like Altstetten and Schwamendingen. Getting the archive right matters now, not later.