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The high costs of maintenance related to pavement wear have caused many countries to prohibit the use of studded tyres. In Japan and Norway, regulations have also been based upon the health aspects of the road dust. In Japan studded tyres are prohibited and in Norway, restrictions have been placed on the use of studded tyres in some larger cities. In Sweden, wear particles from pavements, tyres, brakes and winter sanding/salting, have received a lot of attention the last few years. The reason for this is that measurements have shown that these particles are the main reason that the upcoming environmental quality standard for inhalable particles (PM10) will not be reached in many cities. The problem mainly occurs during dry episodes in winter and early spring and is mainly a result of studded tyre use and winter maintenance. A lot of new knowledge about wear particles is needed in order to develop cost-effective measures to deal with them. A great advantage is the possibility to study aerosols from each source both separately and in different combinations in a controlled environment. At VTI (Swedish National Road and Transport Research Institute) a road simulator (PVM), previously used for pavement and tyre wear studies, is used as a wear particle generator. The PVM can be equipped with different pavements and tyres and even friction materials such as sand can be applied. The PVM can be used at speeds up to 70 km/h and the pavement can be dry or wet. Also the temperature in the hall can be regulated below zero degrees centigrade. In this paper some results from the WearTox project will be presented. The production of PM10 from two pavements worn by studded tyres and friction tyres has been studied as well as the physical and chemical properties of the wear particles produced.

The High Coast Bridge is one of the world´s longest suspension bridges. The waterproofing and pavement for this bridge had to be chosen with care. A lowest average temperature of -–20°C, a minimum temperature of -–40°C and a maximum temperature of +30°C have been recorded in this reigon of Sweden. To be able to recommend the most suitable system for the bridge, a research project was started by the Swedish National Road Administration as early as 1992. As a result of research and testing during the project period, a suitable system for the bridge was suggested by the Swedish Road Administration in 1996. The waterproofing and pavement system chosen for the High Coast bridge consists of an epoxy primer system, an SBS-modified bituminous sheet layer, coarse aggregate mastic asphalt with SBSmodified bitumen and split mastic asphalt with SBS-modified bitumen and fibres. Various waterproofing and pavement producst and systems were tested in the research project, both separately and in different combinations for evaluation. Laboratory testing was performed at the Swedish National Road and Transport Research Institute (VTI), starting in 1992. Testing covered characteristics and performance of the various products and systems at low and high temperatures. Important parameters studied for total built-up systems included adhesion (to steel deck and between layers), shear and sliding resistance. Systems with SBS-modified bituminous sheet (3.5 mm thick), SBS-modified fine aggregate mastic asphalt (4 mm) and conventional fine aggregate mastic asphalt (4 mm) were compared. In 1993, eight different systems were laid on a steel bridge at Pitsund (further north than the High Coast Bridge) for evaluation on site and laboratory testing at VTI. Fatigue tests of the entire waterproofing and pavement system were performed for four possible systems and the reference system at the Otto Graf Institute (FMPA) in Stuttgart. Testing was performed in accordance with the German ZTV-BEL ST-92 “Dauerschwellbiegeprüfung”, but at temperatures from -–30°C to+3°C. The public procurement was completed in July 1996. The system was laid during late summer and autumn of 1997. Quality control testing was performed. Samples of all products used were taken during work on the bridge.