Fernandes, PauloPereira, S. R.Bandeira, J. M.Vasconcelos, LuísBastos Silva, Ana2016-04-132016-04-132016-04-08P. Fernandes, S. R. Pereira, J. M. Bandeira, L. Vasconcelos, A. Bastos Silva & M. C. Coelho (2016): Driving around turbo-roundabouts vs. conventional roundabouts: Are there advantages regarding pollutant emissions?, International Journal of Sustainable Transportation, DOI: 10.1080/15568318.2016.11684971556-83341556-8318http://hdl.handle.net/10400.19/3157This paper addresses the impact of turbo-roundabouts located in urban areas on pollutant emissions using field measurements of vehicle activity data and road congestion levels. The research also compares the emissions of vehicles moving along a turbo-roundabout and a conventional multi-lane roundabout. Based on field measurements taken at turbo-roundabouts without curb dividers located in Grado (Spain) and multi-lane roundabouts in Aveiro (Portugal), three representative speed profiles for each speed trajectory were identified: no stop (I), stop once (II), and multiple stops (III). This study also develops discrete models for turbo-roundabouts and multi-lane roundabouts in which the relative occurrence of those speed profiles is expressed as a function of the entry and conflicting traffic flows. The Vehicle Specific Power (VSP) methodology is then employed to estimate second-by-second pollutant emissions. This study tests the hypotheses that emissions are impacted by the differences in: 1) the characteristics of speed profiles in each movement; 2) the volumes of entry and conflicting flows; 3) the overall saturation level; and 4) the transportation facility considered (turbo-roundabout /multi-lane roundabout). Considering the selected case studies and traffic demands, vehicles at turbo-roundabouts generated more emissions (15-22%, depending on the pollutant) than multi-lane conventional roundabouts, especially under medium and high congested levels. These findings suggest that there are no advantages in implementing turbo-roundabouts from an environmental point of view, even in no saturated conditions.engTurbo-roundaboutsMulti-lane roundaboutsSpeed ProfilesDiscrete ModelsEmissionsjournal article10.1080/15568318.2016.1168497