FASTEST PATH VEHICLE SPEED ANALYSIS AT STANDARD TURBOROUNDABOUTS WITH VARIOUS APPROACH LEG POSITIONS

In previous studies, a new (improved) turboroundabout design approach based on the rules of the design vehicle movement geometry was proposed, and the optimal design of elements of standard turboroundabouts for various design vehicle scenarios, circulatory roadway radii, and approach leg positions was defined. Within the scope of this research, the applicability of the current Dutch calculation model for fastest-path vehicle speed analyses at standard turboroundabout schemes designed by a previously described procedure was examined. Research results have shown that this Dutch calculation model does not apply to standard turboroundabouts whose approach legs are aligned under various angles and translatory shifted regarding the roundabout geometric center, and therefore, should not be used for speed analyses at this roundabout type until a new calculation model, which corresponds to the real traffic situation, is developed

ASSESSMENT OF NOISE MITIGATION MEASURES IN URBAN AREAS

U radu je na primjeru Masarykove ulice smještene u užem centru grada Zagreba prikazan postupak ocjene učinkovitosti različitih mjera za smanjenje razina buke koje se odnose na upravljanje prometom. Analiza stanja bučnosti za šest različitih scenarija provedena je metodom računalnog modeliranja u specijaliziranom računalnom programu za predviđanje razina buke LimA, prilikom čega je definiran onaj optimalni koji je rezultirao najvećim smanjenjem razina buke u Masarykovoj ulici te najmanjim povećanjem razina buke u okolnim ulicama. Rezultati proračuna validirani su kratkotrajnim mjerenjima razina buke na terenu u dnevnom, večernjem i noćnom periodu.Within the scope of this study, the assessment of effectiveness of various traffic management and engineering noise mitigation measures at Masarykova Street located in the narrower centre of the city of Zagreb was made. Noise analyses were carried out by means of noise modelling procedure using the specialized noise prediction software LimA. Six different noise mitigation scenarios were observed, and optimal one regarding the amount of noise reduction in Masarykova Street and the amount of noise increase in adjacent streets was defined. Noise modelling results were validated by short term noise measurements carried out in day, evening, and night periods

Geometric design of turbo roundabouts

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.Turbo 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

Sight distance evaluation on suburban single-lane roundabouts

U radu se obrađuje problematika preglednosti na izvangradskim kružnim raskrižjima. Dan je pregled postupaka određivanja potrebne preglednosti, prikazanih u propisima, normama i smjernicama koji vrijede u Austriji, Francuskoj, Hrvatskoj, SAD-u, Srbiji i Švicarskoj. Detaljno su prikazani utjecajni parametri i postupci određivanja polja preglednosti definirani u razmatranim dokumentima. Istaknuta je raznolikost u pristupima ispitivanju preglednosti te je dan komentar rezultata ispitivanja provedenih na teorijskom primjeru izvangradskog kružnog raskrižja.The issue of sight distance evaluation on suburban single-lane roundabouts is analysed. An overview of regulations, standards and guidelines applied in Austria, France, Croatia, USA, Serbia, and Switzerland, which describe procedures for determining the necessary sight distance, is given. Influential parameters for defining clear vision areas for intersections, defined in the aforementioned documents, are presented in detail. An emphasis is placed on the diversity of sight distance evaluation approaches, and test results obtained on a theoretical example of a suburban roundabout are commented on

Impact of vertical traffic calming devices on environmental noise

Sve veći broj stanovnika u urbanim sredinama izložen je štetnom djelovanju buke okoliša, koja u značajnoj mjeri narušava njihovo zdravlje i kvalitetu života. Dominantan izvor buke okoliša u takvim područjima je cestovni promet, a jedna od učestalo primjenjivanih mjera za smanjenje razina buke je smanjenje brzine vožnje. U radu je analizirano kako oprema za smirivanje prometa, koja se uobičajeno primjenjuje radi povećanja sigurnosti prometa, utječe na smanjenje razina buke. Analiza je provedena na sedam dvotračnih dvosmjernih gradskih cestovnih prometnica na kojima su ugrađeni različiti tipovi umjetnih izbočina i uzdignutih ploha.Increasing numbers of people living in urban areas are being exposed to harmful action of environmental noise, which severely affects their health and quality of life. The predominant source of environmental noise in such areas is road traffic, and a frequently used measure to curb down this noise involves reduction of driving speed. The influence of vertical traffic calming devices, normally used to improve traffic safety, on the degree of noise reduction, is analysed in this study. The analysis was carried out on seven urban two-lane two-way roads, on which various types of speed bumps and speed humps are installed

Designing highways for the traffic of autonomous vehicles

U posljednjih nekoliko godina sve je veći broj istraživanja koja se bave razvojem autonomnih vozila. Sposobnost autonomnih vozila da samostalno upravljaju, predviđaju situacije, komuniciraju s okolnim vozilima i infrastrukturom te sredinom u kojoj se nalaze, postavlja nove zahtjeve za projektiranje cestovne infrastrukture. Postupna prilagodba cestovne infrastrukture u najvećoj će mjeri ovisiti o stupnju razvoja autonomnih vozila i njihovom udjelu u prometnom toku. U ovom su radu prikazani rezultati postojećih istraživanja vezanih uz geometrijsko oblikovanje autocesta prilagođenih prometu autonomnih vozila te su dane smjernice za provedbu daljnjih istraživanja čiji će cilj biti detaljna analiza svih projektnih elemenata prilikom izgradnje novih ili rekonstrukcije postojećih autocesta, a ovisno o udjelu autonomnih vozila u prometnom toku.In the last few years, there has been an increasing amount of research dealing with the development of autonomous vehicles. The ability of autonomous vehicles to drive themselves, predict situations, communicate with surrounding vehicles and infrastructure, and interact with the environment in which they are located sets new requirements for designing road infrastructure. Gradual adaptation of the road infrastructure will largely depend on the level of development of autonomous vehicles and their share in the traffic flow. This paper presents the results of existing research related to the geometric design of highways adapted to the traffic of autonomous vehicles and provides guidelines for the implementation of further research. The main purpose of the research will be a detailed analysis of all project elements during the construction of new or reconstruction of existing highways, depending on the share of autonomous vehicles in traffic flow

The Influence of Visibility Conditions in Horizontal Road Curves on the Efficiency of Noise Protection Barriers

Ensuring sufficient visibility on planned roads by sight distance testing is an integral part of every project, but problems with visibility can emerge when noise barriers are erected on existing roads. Namely, in order to provide sufficient noise protection, high noise barriers are often placed at minimum distance from the carriageway edge, and additional visibility testing in most cases is not carried out

The Design Vehicle Steering Path Construction Based on the Hairpin Bend Geometry—Application in Roundabout Design

A prerequisite for a well-designed roundabout is the definition of the design vehicle movement geometry and its turning envelopes. This is because kinematic and dynamic requirements lose their importance due to low driving speed. In this paper, the investigation of the deviations of design vehicle steering paths for straight passage through the roundabout constructed according to the two approaches is presented. The first approach (A-1) includes the application of short, straight lines between the adjacent arcs on the path, and the second (A-2) implies the application of consecutive circular arcs. A computer simulation of vehicle movement was conducted using the Autodesk Vehicle Tracking 2020 software. The results showed that A-2, a faster and simpler approach, is applicable with caution, as the resulting turning envelopes derived from this approach are more offset from the roundabout centers compared to the A-1 approach. A total of 72% of right-hand-side path and resulting right-hand-side design vehicle body and chassis turning envelope deviations were between 0.00 and 0.15 m, 27% were over 0.15 m, and 7% were over 0.25 m. This results in larger roundabout entry and exit widths as well as the need for large lateral clearances for entries and exits on roundabouts where heavy pedestrian traffic on sidewalks is expected. The noted offset of left-hand-side design vehicle trajectories on the circulatory roadway (which was mostly between 0.05 and 0.15 m) could have a positive impact on the deflection around the central island

The Design Vehicle Steering Path Construction Based on the Hairpin Bend Geometry—Application in Roundabout Design

A prerequisite for a well-designed roundabout is the definition of the design vehicle movement geometry and its turning envelopes. This is because kinematic and dynamic requirements lose their importance due to low driving speed. In this paper, the investigation of the deviations of design vehicle steering paths for straight passage through the roundabout constructed according to the two approaches is presented. The first approach (A-1) includes the application of short, straight lines between the adjacent arcs on the path, and the second (A-2) implies the application of consecutive circular arcs. A computer simulation of vehicle movement was conducted using the Autodesk Vehicle Tracking 2020 software. The results showed that A-2, a faster and simpler approach, is applicable with caution, as the resulting turning envelopes derived from this approach are more offset from the roundabout centers compared to the A-1 approach. A total of 72% of right-hand-side path and resulting right-hand-side design vehicle body and chassis turning envelope deviations were between 0.00 and 0.15 m, 27% were over 0.15 m, and 7% were over 0.25 m. This results in larger roundabout entry and exit widths as well as the need for large lateral clearances for entries and exits on roundabouts where heavy pedestrian traffic on sidewalks is expected. The noted offset of left-hand-side design vehicle trajectories on the circulatory roadway (which was mostly between 0.05 and 0.15 m) could have a positive impact on the deflection around the central island