Monitoring Procedure established in Directive 70/157/EEC and UNECE Regulation 51
Noise emissions of four-wheel motor vehicles are addressed by Directive 70/157/EEC and the equivalent UNЕСЕ Regulation No. 51 . The noise limits have been reduced several times, the most recent being in 1995. This last reduction did not have the expected effects and subsequent studies showed that the measurement method does not reflect real world driving behaviour anymore. It was therefore decided that, before reducing the limits once again, it is first of all necessary to develop a new test cycle and bring the driving conditions for the noise test closer in line with real life driving operation.
The UN-ЕСЕ Working Group on Noise elaborated a new test method which was published in 2007. During a period of three years this new method was used on a provisional basis in parallel with the existing test method in order to get practical experience with the application of this new method, to evaluate its qualities and to establish a database with measurement results. The monitoring period under UN-ECE Regulation No 51 lasted from 1 July 2007 until 1 July 2009, while the monitoring period under Directive 70/157/EEC started on 6 July 2008 and expired on 6 July 2010. During the monitoring periods the type approval authorities were obliged to execute the noise emission tests according to both methods and to submit the results of both tests to the European Commission.
On the basis of the results of the monitoring data, TNO has executed a study, VENOLIVA [2 MB] , into the differences between the current type approval test method and the new test method.