Tyre-to-road adhesion plays an important role when taking into account transmission of forces between tyres and road surface. It consequently influences vehicle safety. Moreover, it plays a significant role for modelling vehicle motion, which is often applied in the development of automotive active safety systems and in traffic accidents reconstruction. Furthermore, tyre-to-road adhesion properties are dependent on many factors. One of the factors is the type of tyre – summer or winter. This is the reason why it is justified to study the anti-slip properties of summer and winter tyres. This paper shows the method of measuring tyre-to-road adhesion coefficient. It is based on a skid resistance tester SRT-4 that consists of a special dynamometer trailer, towing vehicle and test-measuring equipment. It was designed to be applied in civil/road engineering and further developed. As a result, the SRT-4 system automatically obtains adhesion characteristics, such as the graph of tyre-to-road adhesion coefficient as a function of wheel slip ratio and velocity characteristics of peak adhesion coefficient. Results of the study present the above mentioned characteristics for different types of tyres (summer, winter) in different exploitation conditions. Differences between presented characteristics caused by tyre type and conditions of exploitation are shown. For example, for winter tyres we noticed that the peak value of adhesion coefficient was attained for higher values of slip ratio as compared with summer tyres.

Friction properties of the road surface have a great influence on the safety of automobile motion. These properties are characterized by the tyre-to-road adhesion coefficient, which is measured during the routine and acceptance investigations of roads. In the paper, the method of measurement of this coefficient is presented. For investigation of the tyre-to-road adhesion coefficient the special measurement system was developed. The main part of the system is dynamometer trailer, which makes it possible to measure the friction force between tyre and road surface. The adhesion coefficient as a quotient of the friction force and vertical load is a result of measurements. Additionally the system enables to determine the graph of the adhesion coefficient as a function of wheel slip ratio. In the paper a description of the measurement system and a principle of its operation are presented. Exemplary results of tyre-to-road adhesion coefficients measured on different roads are also presented. The results show many differences between these coefficients in dependence of road upper layer technology, degree of its wear, weather conditions, sliding velocity and others. The system originally designed for investigation of friction parameters of road surfaces can have much wider applications, for example in tyre investigations, for automotive experts, in the work of judgment witnesses and others.

The article presents the results of studies on the influence of the thermal state of vehicle combustion engines on pollutant emissions. This influence was analyzed based on data from Poland’s inventory of pollutant emissions for the years 1990–2017. The results show that during engine warm-up, carbon monoxide emission constitutes the largest share (up to 50%) in the national annual total emission. Volatile organic compounds are next in the ranking, whereas the share of nitrogen oxides is the lowest (less than 5%). Under the model traffic conditions, close to those in Poland’s cities in winter, simulation tests regarding additional pollutant emissions from passenger cars during engine warm-up were also carried out. As a result of the cold-start emissive behavior of internal combustion engines, emissions of carbon monoxide and volatile organic compounds showed a considerably greater impact on national pollutant emission, as compared to carbon dioxide, nitrogen oxides and particulate matter. This is particularly evident for the results of the inventory of pollutant emissions from road transport.

Energy consumption and pollutant emission aspects were ascertained for cars under traffic conditions: in cities, outside cities, on motorways and expressways, with the use of data from the inventory of emissions from road transport in Poland in 2018. The values of characteristics of energy consumption under model traffic conditions, as well as pollutant emissions and energy consumption of cars with internal combustion engines and cars with electric motors, constituted the basis for further analyses and conclusions about the characteristics of the vehicles under the study in terms of energy consumption and pollutant emissions. As a result of the research, it was found in the case of the use of electric drives, a very significant decrease in energy consumption—by 70% and the emission of non-methane volatile organic compounds—at the level of 90%. In the case of the emission of nitrogen oxides, there is a great advantage in relation to cars with compression-ignition engines, while the emission of nitrogen oxides from cars with spark-ignition engines is about two times lower. It was found that the emission of particulate matter for electric cars is about three times higher than for cars with compression-ignition engines and almost six times higher than for cars with spark-ignition engines. On the other hand, the impact on carbon dioxide emissions is small—less than 10%.

The estimation of the values of moments of inertia of vehicles for the needs of accidents reconstruction is very important. Usually, because of the problem of costs, there is no possibility to measure these parameters on a special test rig (physical or torsional pendulum). So, it is justified to look for new methods which would allow to obtain the mass moments of inertia of automobile. Of course, estimation is always burdened with error, but somebody who uses a formula for calculation of moment of inertia should put in the results the range of error of estimated value. In this paper the authors presented their own formulas on the basis of which the values of moments of inertia are estimated. As the basis of their work, a set of measurement results of the moments were used. They were performed by NHTSA for passenger cars exploited in the USA mainly in the 80's and 90's. In used NHTSA database there were also the vehicles that had the identical body version as in Europe. The presented new formulas were obtained using the procedure which was based on Monte Carlo method. However, the Authors decided to propose different formulas for each moment of inertia. They require a certain number of vehicle data, for example mass and wheelbase of a vehicle.

The aim of this study is to investigate the environmental hazards posed by solid particles resulting from road transport. To achieve this, a methodology used to inventory pollutant emissions was used in accordance with the recommendations of the EMEP/EEA (European Monitoring and Evaluation Programme/European Economic Area). This paper classifies particulates derived from road transport with reference to their properties and sources of origin. The legal status of environmental protection against particulate matter is presented. The emissions of particulate matter with different properties from different road transport sources is examined based on the results of Poland’s inventory of pollutant emissions in the year 2018. This study was performed using areas with characteristic traffic conditions: inside and outside cities, as well as on highways and expressways. The effects of vehicles were classified according to Euro emissions standards into the categories relating to the emissions of different particulate matter types. The results obtained showed that technological progress in the automobile sector has largely contributed to a reduction in particulate matter emissions associated with engine exhaust gases, and that this has had slight effect on particulate matter emissions associated with the tribological processes of vehicles. The conclusion formed is that it is advisable to undertake work towards the control and reduction of road transport particulate matter emissions associated with the sources other than engine exhaust gases.