Case-study from Sarajevo: How cities can economically and quickly monitor unauthorized residential construction

In the face of rapid urbanization, especially in post-conflict or rapidly developing regions, monitoring illegal and unplanned construction is vital for sustainable city growth.

A recent study conducted in Sarajevo, Bosnia and Herzegovina, offers a clear methodology and valuable insights into how cities can detect and control urban sprawl using satellite imagery.

Summary of the study

The research focused on a 1 km² test area in the western part of Sarajevo, where large-scale unauthorized residential construction took place between 2001 and 2006. Using high-resolution panchromatic satellite images from the IKONOS satellite (captured in 2001, 2004, and 2006), researchers applied change detection techniques to assess the extent of new construction.

The methodology involved:

• Overlapping satellite images from three years and assigning them to different color bands (RGB):
• This technique allowed visible color differences to highlight changes over time. For example, green areas indicated new construction between 2001 and 2004.
• Visual and computer-assisted analysis helped identify housing units, roads, and land-use changes.
• Field validation confirmed the presence of new buildings.

Key findings

• 141 new buildings were built between 2001 and 2004.
• 42 more buildings appeared between 2004 and 2006.
• Most were illegal single-family homes constructed without infrastructure (sewerage, water, roads).
• Urban expansion closely followed the development of road infrastructure.

Conclusion

• High-resolution satellite imagery is a cost-effective tool for monitoring urban expansion—especially in areas with limited on-ground data.
• Simple visual methods, like RGB photography, can be used by non-experts in city planning departments to detect unplanned growth.
• Illegal construction often precedes infrastructure development, making early detection essential to prevent unsafe or unsustainable settlements.

By applying these techniques, cities worldwide—especially those in similar transitional or high-growth contexts—can better manage and regulate their urban footprints.

Reference

• Mulahusić, Admir; Kanjir, Urša; Radočaj, Dorijan; Jurišić, Mladen; Topoljak, Jusuf; Tuno, Nedim Assessing the Potential of High-Resolution Satellite Imagery for Urban Expansion Analysis // Geodetski list, 79 (2025), 1; 1-16
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