The aim of this paper is to introduce the reader to the construction of an analytical model assessing the effect of increased traffic intensities on extraordinary road traffic events on the amount of expenditures that the road administrators are forced to spend on the extra maintenance and reshaping these alternative diversion routes into the initial technical conditions. The computational mechanism of this model is based on the one hand on parameters of diversion routes temporarily transferring increased traffic intensities (e.g. motorway traffic at closure), on the other hand on approved cost databases for the assessment of road constructions and other regulations concerning the design of road maintenance and repair. In the final part of the paper the applicability of this model in practice is assessed and some negatives that are not included in the final calculation when determining the total costs of the road administrator are mentioned.