The objective of dissertation is to improve the existing methods of management of bridge network on Slovenian roads. To achieve this, a multi-criteria decision support system which as a final result submits a priority list of bridges in need of remediation was developed. The system is divided into project and network level. On the project level values of the selected criteria are determined, while on the network level the obtained values are combined in technical and financial aspect. On technical aspect basis priority list is developed and on financial aspect basis extent of remedial works on each bridge on the priority list is determined. Remedial works are prescribed depending upon bridge network condition and annually available financial resources. In addition, financial aspect enables projection of the necessary financial resources to maintain the network status for the five-year period. Among the selected criteria highest attention was given to determining the deterioration rate of bridges. Effects of multiple parameters of influence upon the speed of deterioration were assessed. Data of regular and main inspections of over thousand bridges over a twenty year period were analysed. Analysis of the available data showed that climate and presence of water under the bridge have the largest impact upon the deterioration processes while the influence of structural material is visibly smaller. According to the analysed data there is no correlation between traffic load and deterioration processes.