Infrastructure managers of medium size bridge stocks are being faced with the task of approximating short, mid to long term financial needs for their infrastructure. This task is particularly demanding due to the lack of relevant information, in particular in forecasting bridge condition and intervention costs. It can, therefore, be beneficial to make cost estimations based on structure types and present condition evaluation. In this article a rational approach for the management of the medium size bridge stock including 654 bridges of a regional road network is presented. The basic methodology is given and it is described how this methodology is adopted considering the available information (data base) on the bridge stock on the structures level. The use of age equivalents is suggested to describe bridge condition and to link directly intervention cost to condition