Energy Consumption and CO₂ Emissions of Road Transport Toll Highways in Spain

Abstract

This paper estimates the energy consumption of transport toll highways for 202 road segments and for seven vehicle types: gasoline cars, diesel cars, motorcycles, vans, articulated trucks, rigid trucks and buses. Energy consumption is related to traffic volume, Annual Average Daily Traffic (AADT) and Annual Average Hourly Traffic per lane (AAHT), and factors such as speed, road slope and percentage of heavy-duty vehicles (HDVs). Energy consumption estimates give an evaluation of the levels of energy efficiency of road segments. Energy consumption is estimated using fuel consumption-speed curves which regression parameters are balanced according with the coefficients from an empirical model based on site survey data. According with the paper, the mean energy consumption and subsequent CO₂ emissions from toll highway segments are estimated to be respectively 1,895 MJ/h/lane-km and 0.15 tCO₂eq./h/lane-km. These values increase to 2,644 and 0.22 if energy and carbon emissions of transport infrastructure are considered. Material Input per Service (MIP) is determined, as the life cycle wide energy consumption by the toll highway construction and vehicles, and set against passenger-kilometres and ton-kilometres transported. If the MIP of the infrastructure construction is allocated to the users according to traffic, the MIP is much higher for motorcycles than for car traffic. The aggregated MIP is significantly lower for articulated trucks than for vans. The aggregate of Spain’s toll highway segments requires 2.6 MJ/tu-km (0.6 infrastructure and 2.0 traffic).