Example of a fatigue life evaluation of noise barriers along a high speed railway line

In 2012 a new high speed railway line located in Lower Austria was put into operation by the Austrian Federal Railways. Different trains passing with a target speed of up to 230 km/h generate a high aerodynamic impact on trackside structures as noise barriers. Soon damages on the mounting detail of noise barrier posts on bridge sections occured and a first evaluation showed that the original mounting detail of the noise barrier posts was likely to not reach its expected lifetime due to fatigue failure. Therefore new constructions for the posts were developed by local engineers and a test installation with the newly designed posts was realized along the high speed railway line. The presented work shows the results of a detailed fatigue life evaluation for details of this new constructions which were assumed to be conservatively designed. Due to the large number of necessary noise barriers along a railway line a more inexpensive design of the noise barrier posts was aspired by the railway operator. Based on the measured impact from long term monitoring along the track the mean aerodynamic load collective for different types of trains was evaluated and used as input for a numerical finite element analysis. Structural hot-spot stresses of the relevant details were extrapolated from the calculations and used for assessment of the theoretical lifetime of the mounting detail based on the linear damage accumulation law according to Palmgren- Miner. With this detailed evaluation the study could show the possibility for improving and simplifying the design of the mounting detail which may lead to reduced construction costs for noise barriers with respect to the lifetime of the structure.