Potential Energy Savings by Reducing Rolling Resistance of Dutch Road Pavements Berthe van Haaster 1 ; Ernst Worrell 2 ; Jan Paul F. Fortuin 3 ; and Willem-Jan van Vliet 4 Abstract: The current study focuses on options to improve vehicle energy efficiency by reducing rolling resistance on Dutch national highways. Different studies of pavement materials have been evaluated, and models have been compared to experimental data to review rolling resistance indicators. The study shows that texture parameters MPD (mean profile depth) and RMS (root mean square) are relevant indicators for rolling resistance, whereas the effect of road roughness (IRI) is found to be larger than indicated in the evaluated models. The effects of other wavelength regions, texture orientation, and road wear need further investigation. The rolling resistance assessment shows that single-layer porous asphalt concrete (PAC) with aggregate size 6=16 (which is most currently used on Dutch highways) has rolling resistance levels that are 8–10% higher than the levels of double-layer porous asphalt concrete (DPAC) with aggregate size 2=6. Switching to DPAC 2/6 for highways would result in energy savings of 2–2.5%. These calculations are based on estimations and results with high uncertainty and should therefore be taken as a rough estimate of the potential energy savings. Further research is recommended to further refine and validate the results of this study. DOI: 10.1061/(ASCE)MT.1943-5533.0000999. © 2014 American Society of Civil Engineers. Author keywords: Rolling resistance coefficient; Dense asphalt concrete; Porous asphalt concrete; Road wear; Road texture; Fuel consumption. Introduction Pavement materials on national roads have gained a lot of attention during the last few decades in the Netherlands. Recent road research has focused on noise reduction, safety, and durability for evaluating road pavements, while reducing vehicle fuel con- sumption by reducing rolling resistance is a topic that has been less emphasized. To investigate opportunities to mitigate climate change, recent initiatives propose to include energy considerations into road pavement assessments. Road traffic on national highways contrib- utes nearly 15 million ton CO 2 emissions per year (Statistics Netherlands; CBS 2011a), providing a scale factor that makes even a small savings percentage count. Rolling resistance is one of the many forces that a vehicle has to overcome when driving. The total vehicle fuel consumption is mainly affected by rolling resistance and aerodynamic resistance, but inertial forces when accelerating and internal friction losses have an effect as well (Bennett and Greenwood 2003; Sandberg et al. 2011a). Internal friction forces include transmission losses, engine friction, and suspension losses. The side-force resistance is an extra contribution to rolling resis- tance that occurs when driving in curves, when driving on the edge of a rut in the pavement, or when there is a poorly adjusted camber angle (Sandberg et al. 2011a). Suspension losses are forces needed to overcome frictional losses in shock absorbers and heating; longitudinal unevenness will cause suspension losses (Sandberg et al. 2011a). At lower speeds the rolling resistance levels are of more importance, and at higher speeds the aerodynamic resistance becomes more important (Sandberg et al. 2011a; Ejsmont and Sandberg 2002). Road pavement characteristics have an influence on rolling resistance levels of roads. High rolling resistance levels lead to higher energy consumption by vehicles, which leads to higher CO 2 emissions. The current study tries to give an overview of the current state of the art on rolling resistance research and energy use while focusing on Dutch road pavements. The main question that will be answered is: To what extent can fuel consump- tion on national highways be reduced by reducing the rolling resistance by changing pavement type? First the methodology of this study is described, after which the theoretical background to the study is provided. This is followed by the results and an evaluation of proposed factors for rolling resis- tance calculations. Conclusions are presented in the last section. Methodology This study reviews available international literature on rolling re- sistance. It consists of an evaluation of the available experimental data, a comparison of the experimental data with the models of roll- ing resistance, and an evaluation of factors for rolling resistance calculations. Three studies with experimental data are included. Rolling resistance measurements have been performed at used test tracks at the A15 and A59 in the Netherlands in 2005 (Roovers et al. 2005), unused test tracks at the N60 in the Netherlands in 2008 (Boere and van Blokland 2008), and test tracks in Denmark 1 Researcher, Copernicus Institute of Sustainable Development, Research Group Energy and Resources, Utrecht Univ., Heidelberglaan 2, 3584 CS, Utrecht, Netherlands (corresponding author). E-mail: A.K .vanHaaster@uu.nl 2 Professor, Copernicus Institute of Sustainable Development, Research Group Energy and Resources, Utrecht Univ., Heidelberglaan 2, 3584 CS, Utrecht, Netherlands. E-mail: E.Worrell@uu.nl 3 Rijkswaterstaat Delft, Dienst Verkeer en Scheepvaart, Directie Ontwerp en Planvorming, Afdeling Leefomgevingskwaliteit, Schoemaker- straat 97, 2628 VK, Delft, Postbus 5044, 2600 GA, Delft, Netherlands. E-mail: Paul.Fortuin@rws.nl 4 Rijkswaterstaat Delft, Dienst Verkeer en Scheepvaart, Directie Ontwerp en Planvorming, Afdeling Leefomgevingskwaliteit, Schoemaker- straat 97, 2628 VK, Delft, Postbus 5044, 2600 GA, Delft, Netherlands. E-mail: Willemjan.van.Vliet@rws.nl Note. This manuscript was submitted on May 31, 2013; approved on December 3, 2013; published online on December 5, 2013. Discussion per- iod open until December 3, 2014; separate discussions must be submitted for individual papers. This paper is part of the Journal of Materials in Civil Engineering, © ASCE, ISSN 0899-1561/04014101(8)/$25.00. © ASCE 04014101-1 J. Mater. Civ. Eng.