Ground vibration, effected by rail services, is an important environmental concern, affecting European citizens nearby any rail infrastructure. Surveys show that many Europeans are subjected to annoying levels of vibration and vibration-induced noise. Although solutions are available for tracks in tunnels, tracks at grade are a much more extensive problem even for vibration-induced noise.
However, solutions for tracks at grade are lacking: for some problems currently no feasible solutions at reasonable cost are available. A group of railway operators, infrastructure managers, infrastructure and rolling stock manufacturers, and construction companies, end users of vibration mitigation technology, have gathered, and have combined forces in the Railway Induced Vibration Abatement Solutions (RIVAS) project.
Providing tools and methods to reduce vibration below the threshold of perception and induced noise below background levels by 2013. The group includes the expertise of research organisations and universities with specialist laboratory and theoretical modelling facilities.
The issues are treated in a holistic way with the focus on reducing the annoyance to line side residents. The project examines all vibration effects and aspects of the system: vehicle, track, propagation, freight and high-speed rail services.
- WP1 establishes the test procedures to monitor and control the performance of vibration mitigation measures under realistic conditions;
- WP2 develops and evaluates mitigation measures based on reducing the excitation of vibration at the vehicle' track interface by improved maintenance;
- WP3 develops and evaluates mitigation measures for ballasted and slab tracks;
- WP4 will develop and evaluate mitigation measures based on sub-grade improvement and ground barriers within the railway infrastructure;
- WP5 addresses the impact of the vehicle.
Each of the solutions is to be validated with field tests on the major European rail networks represented in RIVAS.
The RIVAS results contribute to European standards in particular to a harmonisation of metrics.
The key deliverables of the RIVAS project are
- Mitigation measures for ballasted and slab track
- Guidelines for the design of transmission mitigation measures under/next to the track
- Guidelines for the design of low vibration vehicles
- Assessment of the benefits of mitigation measures in terms of human response and agreed protocol for the evaluation of annoyance and exposure to vibration
- Agreed measurement protocols to assess and monitor the performance of anti-vibration measures
- Agreed protocol to characterise vibration response properties of soils.
- Guidelines for maintenance of track and vehicles for low vibration.
Design studies and numerical modelling of the influencing parameters have been performed to finally predict vibration levels at hypothetical receiver locations at the reference sites in order to ensure maximum comparability. Vibration reduction strategies based on optimized vehicle design and optimized maintenance of both wheel and track have been worked out and tested.
Designs of wide sleepers in combination with soft under sleeper pads and of rail fastening systems with soft under rail pads have been proposed as being the most promising solutions. Corresponding systems were tested in laboratory. In the last phase field tests were performed. Solutions especially dedicated to reducing vibrations emitted from curves and switches could be achieved.
Vibration reduction measures on the transmission path between track and receiver (analogue to noise barriers) are ideal candidates for retrofitting existing lines as their installation does not require closing the track. Several designs have been studied by computer simulation: soil stiffening and sheet pile walls close to the track, open trenches and trenches filled either with soft or stiff materials. Their effect has been predicted for the reference cases and for two sites, where installation and field testing could be performed. For the latter sites, design optimization has been performed for the relevant frequency range taking into account soil layering. The potential field test sites, which are located in Spain and Switzerland, have been characterized by geotechnical tests.
The RIVAS project has been strongly end-user driven in order to ensure an utmost exploitation of results in practice and to prepare an extensive and fast implementation of technical developments.