Assessment of Railway Live Loads on Buried Pipelines Using API RP 1102: A Case Study for the Colombian Railway Corridor

This study applies API Recommended Practice 1102 (7th edition, §4.5 — railway branch) to assess the combined stresses induced in a buried API 5L X65 steel pipeline (12-inch, t = 0.300 in) by heavy-haul railway live loads, using the Yumbo-Buenaventura multiproduct corridor in Colombia as a case study. The governing design load is the Cooper E-80 standard (Areama), transmitted through a ballast-sleeper-subgrade chain modeled via the Zimmermann (Esveld, 2001), Odemark, and Boussinesq methods. Railway-specific API RP 1102 factors are applied, demonstrating their systematic distinction from the highway-branch factors. The combined effective stress reaches up to 81.4 % of the allowable limit (46,800 psi) in the governing double-track case, confirming structural compliance. The main finding is the fatigue circumferential criterion, as it is near-critical (ΔS_Hr / SFG·F = 88.1 %). A parametric sensitivity analysis identifies wall-thickness loss as the dominant risk variable, with the critical threshold at 38 % wall loss. The methodology is transferable to Colombia's active railway development corridors (Tren del Caribe, Corredor Férreo del Pacífico, Regiotram de Occidente) and to analogous Latin American pipeline-railway coexistence assessments.