ITARI - Integrated Tyre and Road Interaction
Overview
Background & policy context:
Road traffic with its conventional heat-engine vehicles, whose energy efficiency is far from optimal, is one of the main sources of urban pollution from greenhouse gases, and it also contributes to the European Union's excessive energy consumption. With the increasing efficiency of engines, secondary effects such as rolling resistance will play a dominant role when aiming for further reductions in fuel consumption.
Noise pollution from road traffic is another major environmental problem. A major component of road traffic noise is tyre/road noise. To achieve the proposed reduction targets it is necessary to reduce tyre/road noise.
Safety is crucial on road surfaces, so the design of new, low-noise textures or textures with low rolling resistance must not risk the grip potential (especially under wet conditions). Currently more than 40 000 people are killed on EU roads every year. The strategic objective is to cut this number by 50% by 2015 and 75% by 2025. The aim is to design highly sophisticated road surfaces to provide an optimum grip. However high-grip surfaces considered alone may not necessarily be saving fuel or absorbing noise.
Models are needed to assist in the design of road surfaces and to predict their essential properties.
Objectives:
The main scientific and technical objectives of ITARI encompassed three main categories:
- design tools;
- measurement methods;
- a demonstration of production techniques.
The objective for the set of design tools was to allow for virtual design of road surfaces and their essential properties. This included tools for designing:
- low noise surfaces based on a hybrid simulation model for tyre/road noise;
- a prediction tool for rolling resistance as a function of surface properties;
- a prediction tool for wet grip.
Measurement tools were provided for the description of surface properties, especially concerning:
- absorption characteristics of road surfaces;
- flow resistance of surfaces;
- mechanical impedance of road surfaces.
While the development of models and tools took place mainly during the first two years, year three was specifically dedicated to the review and assessment of the project results. The main activities demonstrated and validated the results by:
- suggesting optimised innovative road surfaces with an improved overall performance, based on the models developed for the prediction of noise, rolling resistance and wet grip;
- building such virtually designed surfaces by applying new and innovative road surface technology;
- validating the results by measurements.
Methodology:
The main key for the design of surfaces is understanding the interaction between tyre and road surface, this interaction being responsible for contact forces acting between the two. The contact forces are, at the same time, a starting point for the prediction of noise generation, rolling resistance and wet grip.
The main part of the work is based on the tyre/road noise model developed in the European project RATIN. Models have been developed to predict noise and rolling resistance, which also support the development of prediction tools for wet grip performance.
Despite the complexity of the models, it is essential that the tools can be applied in engineering applications. Therefore one or several surfaces are selected for a paving experiment. These experiments will be made on the full scale paving test site of RWTH Aachen. The demonstration allows for creating desired texture features without the restrictions incurred by the usual material selection or manufacturing process.
In order to verify tools and models, theoretical results are compared with measured performance of the manufactured road surface.
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