Performance Assessment of Turbo-roundabouts in Corridors

There is a widespread agreement in the scientific community that the transformation of a conventional multi-lane roundabout into a turbo-roundabout results in a significant increase of road safety levels. However there is no consensus regarding its effect in terms of capacity, as there are some authors that point towards a small reduction in capacity, namely in the major roads entries. The concept of turbo-roundabout is quite recent and therefore there are only a few studies of its performance, in particular, when applied in a network or in a corridor.In this context, this paper focuses on the evaluation of the performance of the turbo-roundabout solution, when applied in corridor, compared to a normal double-lane roundabout. The analysis was based on two key components: capacity and pollutant emissions. The work was supported by microsimulation techniques using the AIMSUN software, based on a real case study calibrated and validated for this purpose.It was possible to conclude that the turbo-roundabout performance is strongly influenced by the traffic load of the network, severely losing its performance in oversaturation conditions. The performance of the solution was also particularly sensitive to the traffic directional distribution, both in the entries as well as in the corridor. In global terms, it was found that the results for the environmental indicators follow the progress of the capacity indicators.