Influence of cross passages temperatures on the life-cycle cost of technical equipment in a railway tunnel

Abstract

In order to achieve the climate goals, the implementation of sustainable construction is becoming more and more topical in the construction sector. Due to very long service lifes especially in railway projects, the consideration of life-cycle aspects into the early design process is of great importance. Regarding the assessment of the economic pillar of sustainability, life-cycle costing has become an established method. This study presents the application of life-cycle cost analysis (LCCA) for decision aiding in railway construction. The two tunnel tubes of the project Koralmtunnel (KAT) are connected with approximately 70 cross-passages (CPs) at intervals of around 500 m. These CPs serve as escape-ways and additionally host utility rooms for technical equipment (telecomunication, power supply and remote control). First thermal simulations revealed indoor temperatures up to 80 [openbullet] C due to the heat release of the technical equipment without implementation of technical cooling systems in operation phase. This is caused by the limited heat transfer with the surrounding rock and with the adjacent running tubes. Therefore, the implementation of a cooling system is necessary. It is stated that higher indoor temperatures lead to reduced service lifes of the installed telecommunication systems. By the application of Arrhenius equation, the influence of several indoor target temperatures on the expected life time of the installed telecommunication systems has been determined. In order to meet target temperature requirements appropriate scenarios including different cooling scenarios have been designed. Finally, LCCA by application of the net-present value-method (NPV-method) was conducted in order to determine the most economical solution regarding CPs cooling systems based on selected target-temperatures.