Assessing road transportation impacts of connected and automated vehicles for a clean and sustainable mobility

Abstract

In the last years, the increasing availability of diverse sources of traffic information to record massive amounts of data has prompted significant deployments in sensor technologies. Accordingly, some strategies have been proposed to take benefits of these technologies for road users. In addition, connected and automated vehicles (CAVs) will be interacting in the road environment with conventional vehicles, which leads to an uncertainty in terms of the emissions impacts. The presentation will focus on the methodology and some results of the “MobiWise: from Mobile Sensing to Mobility Advising” research project, that will finish in January 2020. The R&D project has the main vision to improve mobility in cities for both commuters and travellers by building a 5G platform that encompasses the infrastructure with sensors, vehicles and people. The conceptual idea of MobiWise is to connect any sensor, person and vehicle, and then it uses all information to improve the user mobility, through a complete network and services platform for an Internet of Things in a smart city. Link-based relationships between speed microscale patterns data of individual vehicles were developed. The variability of speed, road grade and acceleration profiles were analysed in detail, as well as traffic congestion hotspots. VISSIM traffic simulation model was used and it allows exporting full disaggregated vehicles trajectory files that can be used by external applications to assess emission impacts. The performance analysis of different scenarios (regarding the penetration of CAVs) are based on link-specific travel time, carbon dioxide, nitrogen oxides, hydrocarbons and carbon monoxide emissions. Vehicle Specific Power (VSP) is a function of instantaneous speed, acceleration/deceleration, and road grade and allows estimating instantaneous emissions, taking as input the trajectory files given by VISSIM. This method is being refined with an on-board portable emissions measurement system. Preliminary results point out to small reductions in carbon dioxide (1-8%) and nitrogen oxides (1-2%) emissions under CAVs penetration rates of 10 and 20%, and increases in carbon dioxide and nitrogen oxides emissions up to 5% and 8%, respectively, with 50% of CAVs. If CAVs speed limits were decreased from current 120 km/h to 90 km/h, then the system-wide emissions would decrease up to 10% (depending on the pollutant and penetration of CAVs).