The objective of this paper is to estimate marginal costs of railway maintenance and renewal for Switzerland. The hypothesis is that marginal costs of railway maintenance (as well as those for operation and renewal) are a function of different independent explanatory vari-ables. Such explanatory variables are output measures like gross-ton-kilometres or the num-ber of trains as well as technical and spatial features of the railway system. This work should provide some of the information needed for the introduction of a "smart charging" system for track access in Switzerland. Smart charging should ensure fair and non-discriminatory prices for users as well as revenues for future infrastructure investment. It should make time-differentiated charges possible in order to allocate scarce track capacities efficiently as well as allow for rewards to environmentally more efficient vehicles. This shows that it is not a strict marginal cost pricing rule that should be implemented in a modern track charging system. The vision is more complex: The charging system should set the right in-centives, its tariffs should reflect the costs caused and it should ensure the financing of the railway infrastructure.