Flashing green signal, as a part of the green traffic signal, indicates that the green signal is about to end. Drivers have more time to decide whether to stop or pass the intersection since they have prior information that the yellow signal will start. The application of flashing green at the end of the green signal is optional, hence, the question is how engineers could decide to use flashing green or not? The answer to the question should be based on researches on flashing green effects on traffic efficiency and safety at signalized intersections. The aim of this paper is to analyze the impact of flashing green on traffic efficiency by determining the value of effective green time. The research was conducted at two intersections in Belgrade, with and without a flashing green signal. Results indicate that effective green is shorter when flashing green is applied, due to the decreased utilization of the yellow signal.
Nagli porast broja vozila tokom dvadesetog veka je doprineo disbalansu ponude i potražnje saobraćajnog sistema, što za posledicu ima nastanak zagušenja u saobraćaju. Usled pojave zagušenja, neminovno je povećanje vremenskih gubitaka, potrošnje goriva i emisije štetnih materija i buke. Neophodno je delovati na saobraćajnu potražnju i ponudu. Obzirom da su gradske sredine oformljene i često nema prostornih mogućnosti za povećanje kapaciteta, javlja se potreba za upravljanjem saobraćajem svetlosnim signalima. Optimizacijom parametara rada svetlosnih signala se postojećim metodama optimizacije najčešće teži minimiziranju vremenskih gubitaka. Međutim, sa aspekta zaštite životne sredine neophodno je razmotriti i mogućnost minimiziranja potrošnje goriva. U radu je predložena optimizacija parametara rada svetlosnih signala sa ciljem minimiziranja potrošnje goriva i predstavljeni su rezultati sprovedene optimizacije. Pokazalo se da se predloženom optimizacijom ostvaruju uštede u ukupnoj potrošnji goriva, oko 2% u vršnom periodu i oko 5% u vanvršnom, u odnosu na metodu Vebstera.
It is generally accepted that synthetic fi bres provide high UV protection capability of textile products, while cellulose fi bres have low UV absorption capacity. However, textile materials made of synthetic fi bres are not considered to be comfortable for wear in warm weather, whereas cellulose-based textile materials are considered to be much more comfortable to wear, especially in the summer months. For this research, the idea was to produce specially blended knitted fabrics from staple/fi lament hybrid yarns in order to provide clothing materials with eff ective UV protection properties, keeping satisfactory comfort properties as well. To obtain hybrid yarns, folding technique was used. The Ultraviolet Protection Factor (UPF), as a quantitative measure of the eff ectiveness of the material to protect human skin against UV radiation, was determined for the rib knitted fabrics by in vitro test method according to the European standard. The physical properties of the knitted fabrics related to their UV protection properties: bulk density, porosity and air permeability were also determined. The hybrid yarns, from which the rib knitted fabrics were produced, having always hemp yarn as a staple component, caused the diff erences in UV protection capability of the rib knitted fabrics through the infl uence of a fi lament spun component. The hybrid yarn aggregation within knitted fabrics also infl uenced their UPF values. Even though the pure hemp knitted fabric was marked as "UPF>50" (according to European standard) due to natural pigments and lignin in hemp fi bres which act as UV absorbers, most of the hemp/fi lament hybrid yarn knitted fabrics exhibited even higher UPF. Therefore, the engineering approach proposed in this research was confi rmed as an eff ective way to design clothing materials with optimal UV protection capability and other wear comfort parameters. Keywords: ultraviolet protection factor, hemp/fi lament hybrid yarn, knitted fabric, air permeability
The flashing green signal indicates that the green signal will end, and its application at signalized intersections is optional. This paper presents the results of the survey conducted among Belgrade drivers. The survey was conducted in order to analyze behavior, perceptions, knowledge, and attitudes towards the flashing green signal. Results showed that drivers mostly support the flashing green implementation. Also, respondents expressed an opinion that the flashing green improves traffic efficiency and safety. A third of drivers decelerate and stop when flashing green starts. In a situation where the vehicle in front of them decelerate when flashing green starts, 13% of drivers will try to change lane and pass an intersection. This result indicates that drivers of following cars can have conflicting decisions. Results showed that half of the respondents underestimate the flashing green duration while a third of them overestimate it.
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