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Road transport is an important component of urban infrastructure planning in developed countries. Not only big cities but now also smaller cities with a smaller population and a smaller area face the problem of a high number of road vehicles. The operation of these vehicles requires the construction of sufficiently high-capacity roads, intersections, parking lots, etc. And it is at intersections, i.e. places where traffic flows meet, that the biggest problems occur, i.e. high traffic accidents, high noise, deteriorating environment, etc. Standard intersections, especially in terms of capacity, are no longer enough, and therefore atypical intersections of non-standard shapes must be built. However, these can often be dangerous and it is necessary to look for other forms of controlling, or a combination of different types of intersections, i.e., for example, roundabouts with traffic lights. The paper deals with design traffic lights for atypical intersection. There is described used method, i.e. techniques of traffic surveys, capacity assessment according to technical conditions and evaluation of road traffic using a micro simulation traffic model in PTV VISSIM software. For a specific example of an atypical uncontrolled intersection, 3 variants of modifications are presented here and their suitability is assessed on the basis of multi-criteria evaluation. [ABSTRACT FROM AUTHOR]

Traffic volumes in road traffic show growth, especially in developed countries. Where necessary and depending on space, financial possibilities and other aspects, increasingly more capacity roads (multi-lane highways, complex grade-separated interchange, etc.) are being built. The places, where the roads meet (i.e. at the intersections), are the most problematic (traffic accidents, capacity problems, etc.). Standard intersections (i.e. level intersections, roundabouts, intersections with traffic lights or grade-separated interchanges) do not fulfill their task. Traffic designers, in collaboration with traffic engineers, therefore design non-standard types of intersections, which are basically combinations of standard ones. For example, turbo-roundabouts, roundabouts with traffic lights, double roundabouts, and multiple roundabouts, are created. The paper deals with the roundabouts with traffic lights. This type is not common intersection type in the Czech Republic. On the other hand, for example in Holland, it is quite common to meet a turbo roundabout with traffic lights. Some of them are very complicated - for example, with seven traffic lanes on one entrance to the intersection. However, despite their complexity, the traffic on them is smooth. The paper describes the roundabouts with traffic lights from a safety point of view (analysis of conflict situations) and from a capacity point of view. [ABSTRACT FROM AUTHOR]

The paper deals with comparison of selected capacity calculations for roundabouts used in the Czech Republic. Some traffic engineers use the qualitative methods based on Germany methodology HBS, but some ones still use the quantitative methods for capacity assessment of roundabouts. The quantitative methods are based on the traffic volumes on entries and circulatory roadway of roundabout and they usually use an array of coefficients which represent next roundabout parameters. The qualitative methods are also based on the traffic volumes on entries and circulatory roadway of roundabout and they minutely deal with numbers of traffic lanes, time spaces and mainly average delay times (e.g. critical gap and follow-time) and level of service for entries. The method used in the Czech Republic also deals with the capacity of the exits, including influence of pedestrians on pedestrian crossings and volume/capacity ratio for exits. Attention is also paid to the other types of roundabouts, i.e. not only single-lane and double-lane roundabouts, but also mini and turbo roundabouts. This paper presents the results of calculations by both types of methods for various types of roundabouts and shows the differences used methods. [ABSTRACT FROM AUTHOR]

Roundabouts are generally perceived as safe solution of dangerous intersections. If they are built correctly, number of traffic accidents is lower than in case of common intersection types - it relates also to severity of results (i.e. fewer deaths and serious injuries, and lower property damages). In comparison with uncontrolled intersections the roundabouts have higher capacity available. Czech standards and technical conditions assess roundabout capacity on the basis of calculation of capacity for approaches and departures. Both cases take geometric parameters of roundabout, number of traffic lanes, traffic volumes etc. into account. Besides, capacity calculation of departures from roundabout takes account of occurrence of pedestrians on pedestrian crossings. Influence of possible cycle pass (i.e. occurrence of passing cyclists) isn't solved here. One of reasons is the fact that the cyclists must yield to vehicles in the Czech Republic. This paper deals with possibility of change when conversely the vehicles must yield to cyclists on cycle pass (like in some foreign countries) in Czech conditions (i.e. with using Czech standards and technical conditions). This change will certainly influence road traffic and decreases roundabout departure capacity. The paper describes two method of capacity assessment: numerical method according to Czech technical conditions and assessment by micro simulation models made in PTV VISSIM software. [ABSTRACT FROM AUTHOR]

In the last years, turbo-roundabouts replace conventional multi-lane roundabouts with aim to ensure a higher level of traffic safety and capacity. The most important feature of turbo-roundabouts is a spiral course of the circulatory carriageway allowing drivers easily pass through the roundabout from the entry - circulatory carriageway - to the exit without a need to change traffic lanes. Despite of an original proposal assuming the physical separation of spiral lanes, in many countries, the lanes are "separated" with a horizontal road marking only. However, experiences which were observed at turboroundabouts have shown that about 40% of drivers act in illegal behaviour. The ignorance of traffic rules primary leads to an increasing a crash risk and secondary it leads to an inefficient use of both lanes at the entries and on the circulatory carriageway, such as it is on standard two-lane roundabouts. So, the physical separation of traffic lanes has significant importance to ensure a higher level of road safety and subsequently even an efficient use of both lanes at the main "turbo" entries. The effective use of both left (inner) and right (outer) entry lane has a positive impact on the capacity of two-lane entries. In the article, this effect was calculated using a theoretical capacity model. The results show, for example, an increase in the potential two-lane entry capacity about 19% by increasing the left lane use from 40% to 50%. [ABSTRACT FROM AUTHOR]

One of the main points of sustainable infrastructure is to provide their users with benefits throughout the whole lifespan of said infrastructure. In the ambit of transportation, this means providing consistent road user costs consisting of travel time costs, vehicle operating costs and road safety costs. This article aims to describe a novel approach to cost benefit analysis of turbo-roundabouts on a case study. First, the article describes theoretical model for capacity and average waiting time calculation on a one-lane roundabouts and turbo-roundabouts. This method is then applied to the case study's traffic situation for existing roundabout and planed turbo-roundabout. In the second part a novel approach for monetization of road user costs is described. Life cycle cost analysis is performed to monetize road user costs, particularly travel time costs, throughout the lifecycle of the roundabout for variant "Do nothing" and "Do something". "Do something" being reconstruction of existing roundabout into a turbo-roundabout. Paper presents the results of cost benefit analysis of this reconstruction. Conclusions are drawn for expected procurement cost of the planed turbo-roundabout. [ABSTRACT FROM AUTHOR]

The article presents the results of research on traffic safety on roundabouts in the Czech Republic. The project, entitled "The Impact of the Geometry of Construction Elements on Road Traffic Safety and Fluency on Roundabouts and the Possibility of Accidents Prediction" was carried out by VŠB-Technical University of Ostrava over the years 2009 and 2010. The results have shown that two factors have had a major impact on safety, namely the number of lanes and the maximum achievable approach speed on the legs of the roundabout. On double-lane circulatory roadways, more than a fourfold relative accident rate was observed, in comparison with single-lane roundabouts located in similar conditions. When the maximum approach speed reached 70 kph or higher, the accident rate was double in comparison with roundabouts where the maximum approach speed was ensured (by means of construction) to be 50 kph or less. Achieved results of the research have been incorporated into the methodology for designing roundabouts, which is certified in the Czech Republic. [ABSTRACT FROM AUTHOR]

Turbo-roundabouts are becoming a new type of intersections realized in the Czech Republic. Turbo-roundabout is roundabout with special arrangement of two or more lanes, which should ensure greater security and traffic capacity than conventional roundabouts with two or more lanes. This article presents different types of turboroundabouts. Physical separation of lanes of the circulatory roadway in the area of turbo-roundabouts and in the area of their individual types is an often discussed problem. The article focuses closely on the use of physical separation between traffic lanes and describes use of different types of materials and executions that are realized at turbo-roundabouts in European countries. Further, there are also described types of separation of lanes at intersections which have already been implemented in the Czech Republic. The article also deals with road safety according to the number of conflict points at individual types of roundabouts, with the influence of the physical separation of lanes, with the execution of road marking and with water runoff. In conclusion is also mentioned the maintenance of intersections during the winter months. [ABSTRACT FROM AUTHOR]

The article focuses on the issue of road defects, defects of components and materials used on roundabouts, which are located close to industrial zones. These defects are mostly caused by heavy freight vehicle crossing. Defects of the roundabouts may arise solely due to improper geometry of the crossroad itself, but also by selecting building materials inappropriately due to the nature of the transport. The article presents specific examples of roundabouts, described using this issue. In conclusion, there are recommended materials and possible solutions of this problem at the end of the article. [ABSTRACT FROM AUTHOR]

Building of roundabouts has many positive environmental and socio-economic benefits which can be monetized to express the financial value of positive effect they have on their environment. The article shows how the construction of roundabouts can lower the noise pollution created by traffic on urban intersections. The first chapter describes the basic definitions and description for the reader to grasp the basic knowledge needed to understand the main body of the paper. The main part describes the noise level reduction after reconstruction of selected intersection to roundabouts in selected cities of Slovak Republic and Czech Republic. In the last chapter a simple method of monetizing the benefits resulting from noise level reduction is shown. The objective of the article is to show the amount of noise based socio-economic benefits related to construction of roundabouts. [ABSTRACT FROM AUTHOR]