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Subject reviewTurbo roundabouts are lately a more common choice in designing multilane roundabouts. First guidelines for geometric design of this particular roundabout layout were developed by a Dutch Information and Technology Platform CROW in 2008. Soon after, a number of European countries began to develop their own regulations on turbo roundabouts, adjusted to their traffic cultures and their local conditions. In order to present the diversity of design approaches for turbo roundabout planning in various European regions, comparative analysis of turbo roundabout design procedures described in Slovenian technical specifications, Serbian design manual, German working document, and Croatian and Dutch guidelines is made. Relevant influential parameters used in these procedures are commented. Study presented in this paper may contribute to the success of turbo roundabout planning procedure. Keywords: comparative analysis; geometric design; guidelines; influential parameters; turbo roundabouts Geometrijsko oblikovanje turbokružnih raskrižjaPregledni rad Turbokružna raskrižja su u posljednje vrijeme sve češći izbor pri projektiranju višetračnih kružnih raskrižja. Prve smjernice za geometrijsko oblikovanje ovog posebnog tipa kružnog raskrižja razvijene su od strane nizozemskog istraživačkog centra CROW u 2008. Ubrzo nakon toga, nekolicina europskih zemlja započela je s razvojem vlastitih smjernica, prilagođenih njihovim prometnim navikama i lokalnim uvjetima. Kako bi se dobio uvid u raznolikost pristupa oblikovanju turbokružnih raskrižja u različitim europskim zemljama, provedena je komparativna analiza postupaka njihova oblikovanja opisanih u slovenskim tehničkim specifikacijama, srpskom priručniku, njemačkom random dokumentu, te hrvatskim i nizozemskim smjernicama. Komentirani su relevantni utjecajni parametri koji se u navedenim postupcima koriste. U radu prikazano istraživanje doprinijelo bi uspješnosti provođenja postupka geometrijskog oblikovanja turbokružnih raskrižja.

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Previous studies have shown that a valid roundabout design approach should include a determination of design elements based on the position of design vehicle’s movement trajectories obtained by swept path analysis in early project stages, and not a conduction of swept path analysis at the end of design process. Several software which enable such significant progress in the design practice (optimal design of roundabout elements based on the results of vehicle movement simulation) are currently available on the market. Consequently, it is of great importance to know their accuracy. The reliability of vehicle movement simulation results is usually verified by field tests in which the distances between the test vehicle’s movement trajectories are measured by means of a meter, which is a dilatory and time-consuming process. Within the scope of this study, a new approach for determination of the position of test vehicle’s movement trajectories at the test site using a precise GNSS (Global Navigation Satellite System) device is described. The test vehicle was conducting a critical manoeuvre (left turn for 270°) for ten times, and the distances between its movement trajectories were determined by means of a meter and a precise GNSS device. The situation on the test site was then simulated on a computer and the assessment of the accuracy of chosen software for vehicle movement simulation was made.