In this article a practical example on studying vulnerability using the method of the critical scenario and multi-criteria analysis is presented. Giving a simple method to handle reliability related to a certain path, section, link, junction or a whole trip for travelers and operators of urban road networks as users of traffic information systems it would be a huge step forward. The best would be to have one single parameter coming from an engineering calculation or a model, which would mean the same for the user and the engineer, and both of them would be able to use it as it was. Introducing a clear definition of reliability and vulnerability of road networks used by a wide range of applications is of capital importance. This article makes some steps towards achieving this goal.

Gap-acceptance method is one of the classical methods used to analyze capacity of roundabouts. Critical gap has a privileged role in this approach. Different driver behavior and local rules of traffic has a key role in implementing it in the local standard for capacity calculation in each country. Therefore, a reliable method for estimation of critical gap at a certain location can be of great importance. This paper presents the first steps of an experimental investigation and analysis on whether it is possible to find correlation between video-based gap acceptance data and certain design parameters of roundabouts in Hungary. Ten single lane roundabouts of different size were recorded for hours in different locations in and around Budapest to assess gap acceptance data and relate it to certain design parameters like diameter, distance of neighboring entries, entry width, width of splitter island, number of entries over time, and entry angle – or any combination of those. Using only a linear approach, strong positive correlation was found between measured critical gap and distance between legs. There is correlation (not so strong however) between critical gap and (approach) entry width as well as splitter island width, and enough data were examined to say that there is no correlation between central island diameter and critical gap.

Traffic control strategies of signalized circular intersections are analyzed in this article after a brief overview of traffic lights in roundabouts. A detailed description was made on the 'direct' mode of operation of the Hungarian regulation describing three types of control program. Finally a comparison of traffic performance is given based on the main geometric features and parameters of the signal programs with a description of the signal plan structure. The PTV Vissim environment was used to examine and evaluate the performance of each combination through the average delay per vehicle resulting proposals for the application as well as for further studies in subject.

Közúti forgalomszervezés Szintbeni közúti csomópontok teljesítôképessége-Jelzôlámpával irányított körforgalmú csomópontok alkalmazhatósága A közúti infrastruktúra fejlesztés tervezése hosszú távú és rendkívül költségigényes feladat. A fejlesztési döntések nagy távlatokra határozzák meg a közúti közlekedési rendszerek működését. Időnként a műszaki szabályozás és a tervezési előírások eltérnek egymástól, esetenként hiányosak. A gyors építések miatt az egyes előírások szakmai vitája elmarad vagy késik. Ilyenkor a gyakorlat kikényszeríti egy-egy csomópont utólagos átépítését, ami költségigényes, zavarja a forgalmat és csak utólag vagy részben képes javítani a tervezési hibák okozta zavarok kiküszöbölését. A KRESZ előírások is késve követik az építési újdonságokat, tehát fontos az építés és a közlekedés szabályainak egyidejű egyeztetése, amelyhez jelentős segítséget nyújthat egy nem nagyon elterjedt módszer, megoldás tudományos ismertetése, az előnyök részletes bemutatásával.

Cooperative intelligent transport systems and services (C-ITS) are based on periodical data sharing between cooperative V2X communication units (in-vehicle and roadside units, ITS stations) via a short-range ad-hoc network. All participants are able to acquire information several times per second from others such as position, speed and driving direction as well as intentions and event triggered messages like incidents and emergency braking. Roadside infrastructure can share traffic information like road works or speed limits. As such, C-ITS improves road safety and effectiveness of the transportation system while reduces harmful environmental effects. Transportation authorities and road network operators use cost-benefit analysis to decide on necessary developments. Taking into account only the momentary statistical renewal rate of the vehicle fleet (disregarding all handheld devices), a fully capable operation of such a system can only be predicted in more than 10 years. An overview of existing C-ITS use cases throughout Europe and a simplified comparative analysis of estimated costs and quantifiable benefits of such a system in Hungary is presented in this article. Our research assigned the first developments (i.e. technologies and use cases) in the next 1-3 year period to prepare certain parts of the public road network for CAV testing.