2025.11.16 – A Quiet Dutch Street in the Age of Open Data

Posted byLeonardo Tomás CardilloPosted inUncategorized

Key Takeaways

What one street can reveal

A single residential street in the village of Farmsum, in the Dutch province of Groningen, shows how much can be learned about a place from modern public data: housing details, local history and the wider municipality that surrounds it.

How data layers build a picture

Postcode registries, cadastral maps, municipal geoportals and open aerial imagery together sketch a detailed portrait of the homes along this street, even when individual properties remain anonymous.

Why interpretation is essential

Different sources sometimes disagree on details such as floor area or building year. Those mismatches are a reminder that open data always needs careful reading rather than blind trust.

Privacy in a mapped world

Even when information is technically public, there is a difference between consulting it and broadcasting a full residential identity. Responsible use of data means describing the setting without turning a private front door into a spectacle.

Story & Details

A northern village framed by sea and clay

Farmsum lies in the north of the Netherlands, close to the port town of Delfzijl and within the municipality of Eemsdelta in the province of Groningen. It is part of a coastal landscape of clay soils, dykes and long horizons, where the relationship with the sea has always been practical as well as poetic.

Historically, villages in this region grew on man-made dwelling mounds known as terps, built to keep homes dry when the water rose. Farmsum developed around a church, a manor house and waterways that linked it to trade and shipping. Today, it feels much more like a residential satellite of the nearby harbour, but the old layers are still visible in its church tower, historic streets and industrial skyline.

Eemsdelta itself is a relatively new administrative name. The municipality came into being in January 2021 through the merger of Appingedam, Delfzijl and Loppersum, bringing together historic towns, villages and industrial zones under a single local government. That government now oversees everything from housing and heritage to climate adaptation and energy projects.

A short street with many records

Within this setting, one quiet street in Farmsum stands out as a useful case study. It is a short row of homes with house numbers running from 1 to 45, all sharing the postcode 9936 CR. The architecture is modest: pitched roofs, brick façades, small front gardens, and a mix of detached and semi-detached houses typical of mid-twentieth-century developments in the region.

Public databases say a great deal about these properties without naming any residents. National address and building registers show how each home is positioned on its plot and how the street fits into the wider postcode grid. Cadastral maps add parcel boundaries and land-use categories. Municipal geoportals reveal zoning rules and local planning decisions. Many of these tools can be opened directly in a browser, allowing users to zoom from the national level down to specific streets.

One particular home on the street illustrates both the power and the limits of this information. Cadastral and housing statistics describe a detached single-family dwelling on a plot of around 165 square metres, with a living area in the region of 118 square metres. Older descriptions refer to the house as dating from roughly the mid-1940s and mention a slightly smaller floor area of just over 100 square metres. The difference might come from renovation, a later recalculation under new measurement standards, or simply from the use of rounded figures.

That gap is small, but it is instructive. It shows how even official-looking numbers can vary between platforms, especially when they were recorded at different times or for different purposes. Open data is not a single monolith; it is a patchwork of datasets, each with its own methods, update cycles and quirks.

Open data from maps to aerial views

The Netherlands has spent years building an extensive ecosystem of public geo-information. Services such as Publieke Dienstverlening Op de Kaart (Public Services on the Map, often abbreviated as PDOK) distribute government geodata from a central platform, including base maps, building footprints, land-use polygons and more specialised layers. Many of these datasets are classified as open data: free to use, reuse and share, subject to modest conditions.

For a street in Farmsum, that ecosystem offers several perspectives. High-resolution aerial photographs show the arrangement of roofs, gardens and nearby green spaces with centimetre-level detail. National base maps depict roads, waterways and boundaries. Municipal geoportals add local layers such as zoning plans, heritage overlays and noise contours. Universities and research units contribute their own processed datasets, for example extracting building outlines or combining aerial imagery with elevation models for urban analysis.

Eemsdelta participates in this world as both data producer and data user. The municipality maintains its own geographic portals where residents and professionals can explore neighbourhood indicators, housing stock, environmental projects and heritage registers. At the regional and national level, academic and governmental organisations experiment with ways to predict liveability, monitor solar panel uptake or model flood risk using aerial photographs and open geographic datasets.

Balancing openness and privacy

All this information is powerful. It allows planners, researchers, journalists and citizens to understand neighbourhoods in ways that once required long walks with a notebook. Yet for individual residents, it can also feel unsettling to realise how visible their surroundings have become.

A full residential address combines several elements: street name, house number, postcode and municipality. Put together, those details point to a specific front door. Open-data platforms rarely hide such addresses altogether, because they serve important public functions, from deliveries and emergency services to urban planning and democratic oversight. But repeating them in a new context always raises the question of necessity.

In the case of the street in Farmsum, it is possible to describe the setting in rich detail without publishing a complete private address. The story can focus on the village, the street, the style of housing and the kinds of data that surround it. It can discuss typical plot sizes, floor-area ranges and building periods for the row of houses as a whole. It can explain how cadastral parcels are drawn and how aerial imagery reveals the shape of gardens and roofs.

What it does not need to do is linger on a specific front door. The point is not who lives there, but how public data paints a picture of the place.

A wider map than one village

The issues raised by this small street echo far beyond Farmsum. Similar questions arise in other Dutch towns, from industrial districts around ports to commuter communities such as Spijkenisse in the province of South Holland. They appear in different ways again in countries like Portugal, where coastal cities and inland villages also find themselves increasingly visible in satellite imagery, cadastral portals and local open-data dashboards.

In each case, the balance is the same. Public information makes it easier to see how neighbourhoods change, how infrastructure grows and how historic buildings are protected. At the same time, it calls for restraint in how widely that information is rebroadcast when the focus is not an institution or a landmark, but an ordinary home on an ordinary street.

Conclusions

A street that explains a system

The street in Farmsum shows how a modern landscape of registers, geoportals and aerial photographs can turn local geography into structured data. Postcodes, building footprints, parcel boundaries and high-resolution imagery converge on a small cluster of homes, revealing patterns that once stayed largely invisible to anyone who did not live there.

Taken together, these layers explain how municipalities such as Eemsdelta make decisions about housing, planning and heritage. They also demonstrate the care with which national agencies, local governments and research institutions now document and share information about the built environment.

Respecting the people behind the data

At the same time, this small example underlines a simple principle. Data about streets and houses may be public, but the people who live there are not public objects. It is one thing to know that a neighbourhood consists mainly of mid-twentieth-century homes of a certain size, and another to single out a specific address for scrutiny.

The most helpful stories strike a balance: they make good use of open data to illuminate how places work, they acknowledge the limits and inconsistencies in those datasets, and they resist the temptation to turn private dwellings into case studies more revealing than they need to be. On a quiet street in northern Groningen, that balance is already visible in the way the map is drawn—and in what is left discreetly between the lines.

Sources

Appendix

Borgshof

A short residential street in the village of Farmsum, with house numbers from 1 to 45 and postcode 9936 CR, lined mainly with modest mid-twentieth-century homes and small gardens.

Cadastral map

A map that shows land parcels, their boundaries and identifiers, often used by municipalities and national agencies to register ownership, land use and planning information in a precise, parcel-by-parcel way.

Eemsdelta

A municipality in the Dutch province of Groningen, created in 2021 by merging the former municipalities of Appingedam, Delfzijl and Loppersum, and responsible for local services, planning and spatial policy in the wider region.

Farmsum

A village near Delfzijl in the province of Groningen, historically developed on man-made dwelling mounds and now part of the municipality of Eemsdelta, combining traces of older rural life with modern industrial surroundings.

Kadaster

The Dutch Cadastre, Land Registry and Mapping Agency, a national organisation that records property and land rights, produces official maps and plays a central role in distributing government geodata.

Open data

Data that is made available by organisations for anyone to use, reuse and share, usually under simple licensing conditions, allowing researchers, companies and citizens to build new tools and analyses on top of it.

PDOK (Public Services on the Map)

A Dutch platform that distributes geodata from many government bodies through a single access point, offering base maps, thematic layers and services that can be integrated into mapping software and online applications.

Postcode

A code used to identify specific areas, streets or groups of addresses; in the Netherlands it typically consists of four digits and two letters, and can often pinpoint a short stretch of street or a small cluster of buildings.

Spijkenisse

A town in the Dutch province of South Holland, often seen as a commuter community near Rotterdam, mentioned here as another example of a place where open geographic data sheds light on housing and neighbourhood patterns.

Terp

An artificial dwelling mound constructed in low-lying coastal areas, especially in the northern Netherlands, to keep homes and farms above floodwaters before modern sea-defence systems were built.

Published by Leonardo Tomás Cardillo

https://www.linkedin.com/in/leonardocardillo

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