Rehabilitation Techniques for Aged Railway Tunnels

Due to fact that most of the railway tunnels in Croatia were constructed around hundred years ago, and taking in consideration lack of investments and maintenance strategies, there is an increasing need for their rehabilitation. However, this need is far greater than the available financial framework and therefore it is necessary to properly define the rehabilitation priority list and to apply the state-of-the-art rehabilitation methods to improve the safety and functionality aspects. This will result in overall lifetime increase of these critical infrastructure objects. In order to deal with such challenging task, this paper presents the techniques and methodologies for all stages of tunnel rehabilitation process, starting from investigation works in order to determine current condition of tunnel, through development of rehabilitation design, implementation of rehabilitation measures and quality control programme. The problems of non-satisfactory free tunnel profile, lining instabilities, excessive drainage of groundwater etc. will be presented through the examples of several railway tunnels in Croatia.