Road pavements and PM10: summary of the results of research funded by the Swedish Transport Administration on how the properties of road pavements influence emissions and the properties of wear particles

Download
Christer Johansson

Wear particles from road pavements contribute to high particle concentrations in Swedish road and street environments. In order to obtain an idea of how the properties of road pavements can be influenced so as to reduce the emissions, several research projects were performed during the last century, mainly by the Swedish Road and Transport Research Institute (VTI), SLB Analysis at the City of Stockholm Environmental and Health Administration, and the Institution of Applied Environmental Research (ITM), Stockholm University. At VTI, the research was mainly carried out in a laboratory environment using the VTI heavy vehicle simulator. SLB Analysis and ITM mostly worked in the field with air quality measurements and with a survey vehicle called EMMA which measures particle concentrations behind the two front wheels. The studies mainly focused on the wear resistant pavements used on roads and streets carrying high traffic (SMA) since it is normally these roads and streets that cause problems due to high particle concentrations. However, some tests on ABT in the field have also been carried out. The pavement properties studied are those which are shown by experience to have the greatest influence on the overall wear of pavements, i.e. the maximum size of coarse aggregate and the properties of the aggregate in the pavement. Some alternative pavement designs have also been studied. These are porous asphalt, asphalt rubber pavements, and cement concrete pavements. Overall, the results show that the lower the maximum size of coarse aggregate and the lower the Nordic abrasion value of the aggregate material, the lower the particle formation. Even though experience shows that an AC design wears more rapidly than a similar SMA, no clear differences could be noted between these pavements in the field measurements, probably because the differences are concealed by the dust stirred up which, in field measurements, is difficult to distinguish from direct emission. In the heavy vehicle simulator, rubber asphalt tended in certain designs to produce slightly lower particle emissions, which was not confirmed by the measurements in the field. Porous (quiet) pavement produced lower emissions in the simulator, but since no correct reference pavement was tested, it was considered that the effect was mainly due to the use of a particularly wear resistant aggregate material in the pavement. Measurements in the field were not able to confirm that porous pavements produce lower particle emissions. Cement concrete, on the other hand, was found to cause lower emissions in field measurements, even though there is still some lack of clarity. Particle size distributions in PM10 are similar regardless of which properties of the pavement are changed, and the composition of these particles is fully governed by the mineralogy of the aggregate material. Several important research questions remain. The significance of the direct emissions in relation to suspended dust and the influence of various factors (texture, meteorology, different sources, drainage etc) on the road dust depot processes is important knowledge for better understanding and modelling of the emissions from roads. More knowledge is also needed on how particle emissions are influenced by different standard designs, alternative designs and materials, as well as by the influence of the age and wear of the pavement. The relative contributions which the different aggregate materials in the pavement make to the emissions are also of interest, since the aggregate is often of high quality, while the local stone which is used as the fill is of considerably lower quality. Finally, it may be stated that particle emissions are one of several important properties of road pavements. In choosing a pavement, other aspects must also be considered, such as noise properties, other environmental effects (inclusive of LCA), the effect on fuel consumption and tyre wear.

MEET US


5-6
Dec

Vision Zero for Sustainable Road Safety in the Baltic Sea Region

The conference Vision Zero for Sustainable Road Safety in the Baltic Sea Region is held i Vilnius, Lithuania. VTI is part of the organisation committé and also one of the speakers.

LATEST NEWS


2018-10-18

ADAS&ME is tackling the interaction between people and technology

ADAS&ME is a major EU project focused on automation, the human condition and the human environment. The budget is EUR 9.6 million and VTI is the coordinator.


2018-10-05

Users contribute to the development of train simulators

Apart from advanced driving simulators, VTI has developed several variations of train simulators which are used for training, education and research. In recent years, interest has increased drastically among major actors in the railway sector, and VTI has...


2018-10-03

VR study to contribute to a better working environment for bus drivers

A study where bus drivers test autonomous driving in a VR environment may contribute to a better working environment with reduced stress on the driver and safer driving.


2018-10-02

Non-native plant species spread via transport systems

Researchers at VTI have compiled a report on non-native invasive plant species in Sweden and how they spread via transport systems.


2018-09-20

EU-project VIRTUAL: improving road safety with virtual crash tests

Crash tests are used to improve safety on roads. Therefore the EU now funds a research project to develop virtual methods of crash testing. VTI coordinates the project, called VIRTUAL. The project now invites experts interested in Human Body Modeling to join...


2018-08-28

EU project protects cyclists and pedestrians

According to the World Health Organisation, more than one quarter of road traffic fatalities in 2010 were pedestrians and cyclists. Every year, about 335,000 unprotected road users die because of traffic accidents, which shows the scale of the problem. The EU...