Isolating key features in urban traffic dynamics and noise emission: a study on a signalized intersection and a roundabout

Urban planning and transport network are considered as major urban systems with great impact on the sound environment. Most of the work done in transport management and traffic design to improve the quality of both outdoor and indoor sound environment relies on conventional noise mapping software outcomes. This type of tool is based on macroscopic traffic modelling, considering traffic flow as a steady noise source. A commonly implemented practice intended to reduce noise in urban areas is the transformation of a signalised crossing into a roundabout. However, the individual vehicle behaviour becomes relevant in these decisions, where high time-pattern fluctuations are responsible for changes in the quality of the urban sound environment and of human activity. The present paper studies a set of indicators from isolated key features in these two road traffic configurations and their possible variations (acceleration, heavy vehicles, etc.). A VISSIM microscopic traffic simulation model combined with the CNOSSOS-EU noise emission model is used to test cases based on real situations, now in development stage. The approach presented aims to provide stronger basis in the reasoning behind why different road traffic configurations adopted in the urban planning practice give certain effects in relation to the urban sound environment