2013 - Sweden - Rolling Resistance and Fuel Consumption

In order to evaluate traffic energy changes due to the improvement of road surface standard one need to describe:

• rolling resistance at different road surface conditions

• all other driving resistance

• fuel consumption (Fc) as a function of driving resistance.

Based mainly on empirical data from coastdown measurements in Sweden a general rolling resistance model – with roughness (iri), macrotexture (mpd), temperature and speed as explanatory variables – was developed and calibrated for a car; a heavy truck and a heavy truck with trailer.

This rolling resistance model has been incorporated into a driving resistance based Fc model with a high degree of explanation. The Fc function also includes variables for horizontal curvature (ADC) and the road gradient (RF).

If mpd per road link is reduced by up to 0.5 mm, the total Fc in the road network will be reduced by 1.1%. By reducing iri per link by 0.5 m/km, speed will increase in parallel to reduced rolling resistance and there will be approximately no resulting effect on Fc. If rut depth is decreased in parallel to iri there will be a further increase in speed. For individual road links there might be an energy saving potential if the proportion of heavy vehicles is big enough.