Rail Roughness Monitoring in the Netherlands

Rail grinding is not a time-invariant noise mitigation measure. By reducing the rail roughness, the rolling noise will decrease, but since the rail roughness is not invariant, neither is the noise reduction that is achieved. In general, the rail roughness will again increase after grinding and consequently the rolling noise emission will increase. After a certain amount of time, the rail needs to be ground again to achieve a certain desired average noise reduction. Regular monitoring of the rail roughness condition of the rail is necessary to keep track of the rail roughness and rolling noise emission changes over time. The rail roughness can measured with direct and indirect measurement methods. In the Netherlands, we have developed a monitoring method based on a combination of direct and indirect measurements. The direct measurements are done with commercially available instruments. For the indirect measurements we have developed a new system called ARRoW. In addition, a software program was developed that automatically combines the results from the direct and indirect measurements and delivers the roughness condition of a complete track. The new monitoring method has been successfully used on the new high speed fine (HSL-Zuid) that connects Amsterdam to Brussels and Paris and for conventional rail in a recent research project in the Dutch IPG (innovation) program. The technical details and some of the practical issues involved in the application of these methods will be discussed.