Joël Lelong

Selecting Noise Source and Traffic Representations that Capture Road Traffic Noise Dynamics Near Traffic Signals

Considering trafic dynamics greatly improves noise estimation in urban area. This can be achieved by coupling a dynamic trafic model with both noise emission laws and sound propagation calculation. Determining the relevant noise source and trafic representations to estimate classical noise descriptors (L-Aeq and statistical descriptors) near trafic signals has been recently studied. This research topic is extended in this paper to more specific descriptors which are able to capture noise dynamics at the trafic signal scale, for usual urban trafic situations (upstream, in front of, and downstream a trafic signal) and different distances from the road (5.5, 10 and 15 m). It appears that 14m-line sources ensure an estimation of all descriptors with errors below 2 dB(A) if trafic dynamics is precisely described. Macroscopic and microscopic car-following models are both relevant to highlight noise dynamics triggered by the trafic signal, but some differences between those traffic representations are observed.

Tram noise emission: Spectral analysis of the noise source contributions

In France we can assist to a wide development of tram networks for public transportation in main cities. At the same time arises questioning on the noise emission of trams and possible consequences for resident exposure. A French research project has been conducted for studying noise and vibration emission of trams : this paper concerns the description of the noise emission of passing‐by trams. A measurement campaign was achieved on the city of Nantes network, involving two kinds of trams with distinct technologies and equipment, and tested on two types of tracks having different platform surfaces. Acoustic measurement included both a 2D‐array for noise source identification and a microphone set for vertical directivity analysis. The dominant noise sources are mainly the bogie areas (powered bogies, unpowered bogies) and an extended noise source along the track and the lower part of the tram, all of them involving rolling noise. This paper focuses on the spectral description of the main sources. A paramet...

Analytical solution for bending vibration of a thin-walled cylinder rolling on a time-varying force

This paper presents the analytical solution of radial vibration of a rolling cylinder submitted to a time-varying point force. In the simplest situation of simply supported edges and zero in-plane vibration, the cylinder is equivalent to an orthotropic pre-stressed plate resting on a visco-elastic foundation. We give the closed-form solution of vibration as a series of normal modes whose coefficients are explicitly calculated. Cases of both deterministic and random forces are examined. We analyse the effect of rolling speed on merging of vibrational energy induced by Dopplers effect for the example of rolling tyre.