Assessing Railway Track Embodied Carbon: Life Cycle Inventory Literature Review

Abstract

Efforts to reduce carbon emissions have intensified across the transportation sector, yet life cycle inventory (LCI) data describing the global warming potential (GWP) of railway infrastructure remain limited in the U.S. context. Existing literature is dominated by non-U.S. studies and often aggregates track infrastructure GWP with other civil structures, limiting transparency and applicability. This study synthesized LCI data from 116 case studies reported across 53 sources and isolated at-grade railway track infrastructure. Foreground and background inventory data were compiled for track components, construction and maintenance equipment, material transportation, and end-of-life (EOL) treatment. Case studies were harmonized to a common track-kilometer-per-year functional unit to enable cross-comparison of track GWP. More than 75% of case studies originate from Europe, with concrete-tie and slab-track systems accounting for 74% of all cases, while wooden-tie tracks are underrepresented (10%). EOL treatment data are reported in only 10 studies, and maintenance-cycles are included in approximately half of the sources. The Ecoinvent database is used in 26 studies, while only four incorporate U.S. LCI datasets. Material-level inventories show substantial variability in GWP factors, particularly for steel (0.4–5.7 kg CO₂e/kg), whereas aggregates exhibit the lowest impacts (∼10 g CO₂e/kg). Fuel emissions from maintenance-of-way equipment and material transportation are regarded minor contributors (2%–10% of track GWP). After normalization, overall track GWP converges to a narrow range (21.6–25.7 t CO₂e/km/year) across track systems, indicating that system boundaries and background data choices influence results more than track type. The review also highlighted a critical need for U.S.-specific LCI datasets and environmental product declarations.