Comparison of results from road noise measurements and road noise calculation methods CNOSSOS-EU, Nord2000Road and Nord96

To gain more experience with CNOSSOS-EU a series of road noise measurements was conducted to compare actual measurements with calculated results. These measurements were taken along an urban four-lane motorway in Oslo with speed limit 70 km/h, during the summer of 2023, in accordance with Norwegian standard NS 8174-02 as far as practicable. The resulting road noise levels LAeq, 24t were compared to the calculated levels obtained using three different methods for road traffic: Nord96, Nord2000 and CNOSSOS-EU. The measurement locations were chosen to span from open areas to more complex situations. The key finding is that the calculated noise levels consistently exceed the measured levels across all three calculation methods. Interestingly, the discrepancies between measured and calculated levels are highest in open areas and tend to diminish in more complex scenarios. Specifically, Nord2000 yields higher levels than Nord96 and CNOSSOS-EU, although the differences between Nord2000 and the other two methods become negligible in complex situations. Additionally, the transition in software from Cadna/A to SoundPLAN influences the results. These findings indicate a need for further investigation into source data for vehicles, and potentially road surfaces.