Least-cost path analysis for the missing link of the Pan-American Highway

• Question. Where could a road most feasibly cross the roadless Darién Gap between Panama and Colombia?

• Data. USGS SRTM void-filled elevation (90 m); Natural Earth boundaries and roads.

• Methods

  • Built a cost surface in which cost rises with the square of slope, and areas at or below sea level are nearly impassable.

  • Calculated accumulated cost from Yaviza, Panama, and traced optimal paths to Apartadó and Chigorodó, Colombia.

  • Produced elevation profiles and 3D scenes of both routes.

• Findings. Both routes cross the border through a single low saddle (184.5 m) before diverging in the Atrato lowlands. The Chigorodó route is 8 km shorter (135.9 vs. 144.1 km) and about 5% cheaper. The model also exposed a key limitation: the Atrato River lies above sea level, so the routes cross it at no added cost, which shows why rivers, wetlands, and protected areas are needed in a second iteration.

• Tools. ArcGIS Pro (Spatial Analyst, 3D Analyst)

• Images. 3D scene of the route; 2D path map; elevation profile