The energy use within the transport sector is steadily increasing and this is a development that occurs even though the engines are becoming more energy efficient. Since almost all fuel used is based in fossil energy sources it means that the total amount of CO2 emissions due to transports are also increasing.
To reduce the impact on the climate and to reach the European Union goal of using 20 % less energy, there is a need for research that evaluate strategies for a more energy efficient transport sector. In this research it is important to take on a system perspective where, for instance, study the interaction between the transport sector and energy sector. Also, the transport system should be evaluated in a life cycle perspective. In order to perform such studies it is vital to be able to accurately describe the various conditions that have an impact on energy use and exhaust emissions of transports. An essential follow-up are the prerequisites for these estimations like traffic work, load factors, the composition of the vehicle fleet etc.
Important tools in this work are computer simulation models and equipment for measuring fuel use and describing driving patterns.
We perform research and take on questions about:
The importance of traffic energy use and exhaust emissions in the life cycle of a road.
The effect on traffic fuel use due to road alignment, pavement characteristics, driving patterns and attributes of the vehicle fleet - Analysis at micro level.
The effect on traffic fuel use due to different conditions of the standard of roads, speed limits and the composition of the vehicle fleet. – Analysis at macro level.
We also work with producing engine fuel maps and improve the estimations of vehicle parameters, such as rolling resistance and aerodynamic drag, which are important input data for estimations of fuel use. We have developed methods to estimate these variables for any segment of the vehicle fleet. Furthermore, we can deliver basic data regarding fuel consumption and exhaust emission.
Examples of projects:
MIRIAM (Models for rolling resistance In Road Infrastructure Asset Management Systems) is a collaborative research project with members from several European countries and also the US. The aim is a more environmental friendly and energy efficient road infrastructure which will be reached by reducing rolling resistance. For instance, the effect of road surface characteristics on traffic fuel use is studied and also the importance of rolling resistance in the life cycle perspective of a road.
The project analysis the effects of allowing longer and heavier vehicles, both trucks and cargo trains, and in what degree there are benefits with doing this. Energy use is one of the parameters that are studied.
Production measurements of rolling resistance
The aim is to develop improved vehicle parameters for describing driving resistance for light and heavy duty vehicles, where heavy vehicles (40 – 60 tonnes) are of particular interest.
ELVIS aim at analysing how the railway system can be more effective by using longer and/or heavier cargo trains. This will be evaluated by measuring electricity consumption and by a cost benefit analysis. It will also be analysed how network capacity, other traffic, operator needs, robustness etc. are affected by the physical and temporal space that are allocated to a specific train.
National traffic emission calculations
Every year VTI performs estimations of exhaust emissions and fuel use for the road traffic in Sweden. The calculations are performed with HBEFA 3.1 and are the basis for the national emission report.