Hans van Leeuwen, Managing Director – DGMR Consulting for construction, industry, traffic, environment and software
Monitoring noise & vibration and asset management
Long term noise and vibration monitoring is one of the new developments of the recent years. Especially the combination of including information such as running speed, meteorological information and the identification of the passing vehicles. A microphone at a few meters from the track and two vibration accelerometers on the rails of the two separated tracks (directions) give a huge amount of information on noise and vibration levels of passing vehicles.
For this data the absolute, high accurate, noise and vibration level is less relevant. The differences from day to day and the variation between the vehicles is the main issue. The trend analyses of the noise and vibration is the main result of this long term monitoring. This data transformed to information is extremely useful for asset management of maintenance of the infrastructure and/or the vehicles.
A test project where synchronized long term noise and vibration monitoring was done for over more than 1,5 year shows extreme interesting results. Monitoring systems were placed at four locations along a light rail network. The parameter passing speed, meteorological conditions, like temperature and humidity of the rail were measured and vehicle identification was added to detect noise and vibration events.
One of the interesting results of the monitoring is the effect of the increasing roughness of the tread of the rail. Depending on the construction and geometry of the track, the composition of the various vehicles, the running speed or other parameters, there is a huge effect on the noise emission. The variation is between a few tenth of a dB(A) per month and 0.9 dB(A) per month. One of the conclusions is that the high increase of the noise level also needs a frequent grinding of the track. The efficiency of the grinding method of the grinding procedure is also an aspect under investigation. With the optimization of the grinding method, lots of effort and therefore also cost will be saved.
One other aspect is the condition of the vehicle. When adding the vehicle identity one gets results on the noise emission of it and also the increase of the noise due to the condition of the wheels and any flat sides on the wheel. The paper will give the aspects on long term monitoring, the conversion of data into information and method analyses how to get to asset management in relation to rail and wheels.