European Directive 2002/49/CE on the evaluation and management of environmental noise highlights the need to inform residents about the hazards and impacts of environmental noise and stresses the need to adopt noise prevention and mitigation action plans. In particular, it compels large cities to produce noise maps. In France, this requirement to take account of noise, especially road noise, applies to every conurbation that needs to implement an Urban Travel Plan (Plan de Déplacement Urbain (PDU)) as laid down by the Domestic Transport Policy Act (LOTI).

From noise calculations to an integrated approach using Geographic Information Systems (GIS)

Standardized methods are available that meet these legal obligations, particularly the production and dissemination of noise maps for major conurbations. These maps are based on simplified urban noise propagation models, and use sound source models, for roads in particular, that apply average traffic conditions.
However, recent studies show that noise is only one of many factors that create the disturbance individuals experience: lighting, olfactory and aeraulic conditions also play a role in characterizing a location. Today, in order to understand the urban environment it has become essential to combine data of different types, i.e. physical (thermal, acoustic, luminous, etc.) and “societal” (demography, the property market, etc.). For example, recent research, conducted in particular at the IRSTV (Institute for Research on Urban Sciences and Techniques) in collaboration with IFSTTAR, has attempted to develop integrated multi-physics approaches within a GIS, in order to provide computation, representation and information dissemination tools for the various stakeholders (the scientific community, local government and residents).

From static modelling to a dynamic description of urban noise

In the case of urban traffic noise, although the currently available tools meet the applicable regulations, which are based on a static description of traffic, their limitations are often apparent when more detailed data are required (quantification of noise emergence, consideration of the dynamics of traffic noise). Difficulties are also encountered when the impact of certain design changes needs to be evaluated, for example when intersections or the type of road are modified, or when exclusive rights-of-way are created for public transport.
This situation has led us to develop a special approach based on the dynamic modelling of traffic flow. This was developed in the Transport and Traffic Engineering Laboratory (LICIT ENTPE/IFSTTAR) and allows us to evaluate fluctuations in the traffic, caused by variations in flow, reductions or increases in capacity (as a result of the characteristics of the road), or traffic signals. This type of model is also able to simulate traffic flow within complex intersections, or the behaviour of clean vehicles, such as buses, in urban areas as these have different kinematic characteristics from light vehicles.
LAE’s research is concerned both with characterizing the acoustic emissions of vehicles in the conditions of real use (taking account of transitory kinematic factors and estimating driving behaviour), and describing acoustic propagation in complex environments such as urban areas. They have led to the development of a comprehensive model that is able to estimate noise levels at frontages at a very fine-grained temporal scale, of approximately 1 second.
This tool has been experimentally validated on a section of urban road in Lyon and a district level version is currently in the development phase. This includes new functionalities such as tramline modelling, with the ability to integrate the behaviour of intersection traffic control systems and the mode’s noise emissions.
This work, which is being conducted in close partnership with other teams in the French Scientific and Technical Network - RST (including the CSTB), will ultimately provide local authorities with a robust tool for evaluating the environmental impact (particularly in terms of noise) of a conurbation’s traffic control strategies or traffic management plans.