A numerical study on the influence of peat layer thickness on ground thermal regime along the Hudson Bay Railway

Permafrost thaw driven by climate warming poses increasing risks to linear infrastructure in northern regions, including the Hudson Bay Railway (HBR) in Manitoba, Canada. Peat layers play a key role in controlling ground thermal behavior, yet their influence beneath and adjacent to embankments remains insufficiently quantified. This study uses transient 1D and 2D finite element thermal simulations to examine how peat layer thickness affects ground temperature and active layer thickness (ALT) in a permafrost railway setting. The results show that the ALT response to peat thickness is non-linear and spatially variable: thin to moderate peat increases ALT, while thicker peat can reduce or stabilize thaw near the embankment due to enhanced insulation and lateral heat transfer. Comparisons between 1D and 2D models indicate that neglecting lateral heat flow can lead to 10–20% differences in ALT estimates, particularly near the embankment. Overall, the findings highlight the dual insulating and heat-storage role of peat and demonstrate the effect of lateral thermal processes in embankment-affected permafrost terrain. These results provide preliminary insight into how peat thickness and model dimensionality influence permafrost stability in rail corridors. • Finite element modeling evaluates ground thermal regime sensitivity to peat thickness. • 2D models capture lateral heat transfer, differing 10–20% from 1D simulations. • Active layer thickness varies at different locations relative to the embankment. • Peat can act both as a driving and resisting factor in ground thermal response. • Findings inform monitoring and maintenance for Hudson Bay Railway resilience.