This paper describes a turbo roundabout design procedure based on the rules of design vehicle movement geometry. Previous studies carried out on various junction types have shown that this design approach ensures the usage of optimal roundabout element dimensions as well as safety and comfort during driving. A five-step design procedure is suggested, including a detailed description of relevant influential parameters. They are choosing a design vehicle, implementing the initial roundabout scheme on which the vehicle swept path is analyzed, choosing a method of assigning input parameters for swept path requirements testing procedure, choosing optimal design elements of a standard turbo roundabout, and fastest path vehicle speed analysis.

Road traffic noise is the second largest environmental stressor in urban areas in Europe after air pollution. The harmful effects of noise arise mainly from the stress response it triggers in the human body, which can have significant consequences for physical and mental health. Therefore, the use of a reliable noise prediction model is an important prerequisite for the quality assessment of a number of residents exposed to excessive noise levels and for the selection of appropriate noise mitigation measures. In this study, the analysis of road traffic noise in an urban street in the narrower centre of the Croatian capital Zagreb was performed using four noise prediction models: "RLS-90", "RLS-19", “NMPB-Routes-96 (SET-RA-CERTU-LCPC-CSTB)”, and “CNOSSOS-EU”. LimA V2021 noise prediction software was used for the analysis, and the noise modelling results were validated with short-term noise measurements. The main objective of the research presented in the article was to test the “CNOSSOS-EU” method, recently introduced in Croatian noise control practice, and to gain initial insights into which of the aforementioned noise prediction models is the most reliable for the assessment of road traffic noise in urban environments in Croatia. A comparison of the noise modelling results with the results of short-term noise measurements has shown that the German national calculation methods “RLS-90” and “RLS-19” as well as the “CNOSSOS-EU” method provide significantly more accurate noise predictions than the “NMPB-Routes-96 (SETRA-CERTU-LCPC-CSTB)” method.

Significant progress in autonomous vehicle (AV) development has been made over the years through advancements in artificial intelligence, sensor technology, and data processing; however, many challenges remain, particularly regarding road safety and the complexity of adapting these vehicles to certain traffic situations. As a result, many European countries are funding research projects and setting targets and strategic plans for autonomous mobility, while scientific research proposes establishing standards and design guidelines for adapting road infrastructure to new transportation trends. This review paper examines physical road infrastructure in the era of AVs and identifies potential modifications, considering the development of AVs during both the early and later stages of their introduction into mixed traffic flow. Accordingly, necessary road infrastructure adaptations and the main design parameters affecting road geometric design for AV operation are presented. The design parameters considered include stopping sight distance, vertical curve radii, straight sections, lanes, and others. Furthermore, potential changes in existing physical infrastructure are illustrated using the example of a deceleration lane. Whether it is new infrastructure or modifications to existing infrastructure, both are analyzed in terms of the proportion of AVs in the traffic flow.

Previous studies have shown that existing turboroundabout design procedures, in which swept path analyses are conducted at the end of design process, contain certain disadvantages and understatements which can lead to oversized or undersized turboroundabout solutions i.e. low intersection capacity, poor traffic safety, low driving comfort and high construction costs. Within the scope of this study elements of standard turboroundabouts were designed in accordance with the design vehicle movement trajectories obtained by the swept path analyses. Reliability of the software used in these analyses was verified by the real drives at the test site. Geometric design of standard turboroundabouts was conducted with variation of following influential parameters: design vehicle; circulatory roadway radii; approach leg offset and angle value. Design approach applied in this research resulted in optimal intersection design regarding the occupation of surrounding area and the design vehicle swept path requirements. Circulatory roadway radii and approach leg offset and angle limit values applicable on this intersection type are determined, taking into account the real traffic situation. Additional practical contribution of this research lies in the ability of application of research results in revision of existing guidelines for the design of turboroundabouts, as well as in development of new guidelines in countries which still do not have their own regulations on the design of this rather new multilane roundabout type.