Built-Up Land Nearly Triples Along the Islamabad Expressway, Driving Landscape Homogenization (2010–2024)

Rapid urbanization along transportation corridors is a key driver of land transformation and landscape homogenization in developing mega-cities. This study analyzes land use and land cover (LULC) change within a 5 km buffer, from Gulberg to T-Chowk, along the Islamabad Expressway, Pakistan, from 2010 to 2024, using multi-temporal Landsat imagery (2010, 2015, 2020, 2024) and landscape metrics. Built-up area increased by 190.8% (51.02 to 148.34 km2) between 2010 and 2024. The expansion is accompanied by sharp declines in vegetation (−36.0%; 89.17 to 57.06 km2), barren land (−93.8%; 63.88 to 3.94 km2), and water bodies (−64.2%; 8.20 to 2.93 km2). All class-area estimates were derived from the R landscapemetricspipeline and independently verified against visual inspection of the classified rasters, confirming correct class labelling throughout. Landscape structure shifted towards homogenization, with Shannon’s Diversity Index decreasing from 1.19 to 0.74, Patch Density from 74.39 to 21.08 patches per 100 ha, and Edge Density from 219.65 to 99.78 m/ha. LULC maps achieved an accuracy greater than 96% (κ>0.96) for each classification year, and metric estimates showed cross-platform agreement between R and FRAGSTATS within ±5%. A distance-zone analysis across four successive 1.25 km bands from the Expressway showed that this expansion was pervasive rather than confined to the roadside, with the urban share of classified land rising by 43.6–47.7 percentage points in every band. A complementary 300 m × 300 m fishnet-grid multivariable logistic regression (n=2162 cells classified as non-urban in 2010) identified proximity to existing 2010 built-up land and location within a formal housing scheme as the strongest independent correlates of conversion to urban land (AOR = 1.88 for housing-scheme proximity; 95% CI: 1.38–2.56), with acceptable model discrimination (AUC = 0.739). These findings indicate rapid corridor-scale consolidation associated with infrastructure-led growth, reducing landscape heterogeneity and potentially weakening ecological resilience. Unlike previous city-scale studies in the Islamabad–Rawalpindi region, this study adopts a transportation-corridor perspective, combining descriptive landscape ecology with spatially explicit statistical modelling to quantify both the pattern and the spatial drivers of infrastructure-led land transformation. The study underscores the necessity for integrated, corridor-scale land-use governance—including transit-oriented development and landscape-metric-based ecological zoning—to balance urban expansion with ecosystem sustainability.