In order to evaluate the general conditions (i.e. safety, serviceability and durability) of tunnels, a detailed analysis of the lining structure and surrounding rock mass is required. During the service life of the tunnel, regular survey activities should be performed to check the tunnel conditions and regular conservation practices are necessary to preserve the tunnel’s structural integrity and guarantee safety and serviceability during operation. The collection of data about tunnels since their construction and during their service life may help in the assessment of tunnel conditions and improve the understanding of tunnel degradation with time. The long term behaviour of the Swiss National Road tunnels has been studied and a specific data base has been developed. Based on detailed literature review and analysis of principal inspections results collected in the data base, the main pathologies that affect the Swiss road tunnels have been identified. In addition, by means of a specific data analysis, both degradation potential and rate have been investigated and the main influence factors involved have been selected. The obtained results confirm what was expected according to observations in the past. After a brief introduction about the tunnels of the National Roads network, this paper describes the main steps of the data analysis, different methods used and main results of the analysis. Due to the fact that the tunnels within Swiss National Roads were developed during the 60s, attention has been focused only on concrete lined tunnels.