In this paper we analyse railway tracks using survival analysis. The purpose is to derive the effect from increased tonnage on rail renewal cycles and to calculate the associated marginal cost. A censored data set of 1 500 observations over the Swedish main railway network is used. We specify a Weibull regression model and a deterioration elasticity is estimated for total tonnages as well as passenger and freight tonnages separately. Marginal costs are calculated as a change in present values of renewal costs from premature renewal following increased traffic volumes. The marginal cost for freight trains is estimated to SEK 0.0007 and for passenger trains to SEK 0.0013. These estimates are in line with previous cost function estimates using Swedish data.