1,718 research outputs found

    A constant travel time budget? In search for explanations for an increase in average travel time

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    Recent research suggests that during the past decades the average travel time of the Dutch population has probably increased. However, different datasources show different levels of increase. Possible causes of the increase in average travel time are presented here. Increased incomes have probablyresulted in an increase in both costs and benefits of travel. The increase in travel time may also be due to benefits having increased more rapidly than costs. Costs may even have decreased due to the increased comfort level of cars and increased opportunities offered to make double use of one's time(e.g. working in a train)

    Позиціонування вугільної галузі у зовнішньому енергетичному балансі України

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    Здійснено формування зовнішнього енергетичного балансу з розрахунком показника чистого експорту. Виконано комплексну оцінку співвідношення обсягів виробництва та споживання вугілля в Україні. Виявлено невідповідність обсягів виробленого та спожитого вугілля та його акумуляцію в Україні. Обґрунтовано необхідність зменшення обсягів імпорту вугілля. Ключові слова: виробництво, зовнішній баланс, імпорт, комплексна оцінка, споживання, формування, чистий експорт.Осуществлено формирование внешнего энергетического баланса с расчетом показателя чистого экспорта. Выполнена комплексная оценка соотношения объемов производства и потребления угля в Украине. Выявлены несоответствие объемов произведенного и потребленного угля и его аккумуляция в Украине. Обоснована необходимость уменьшения объемов импорта угля. Ключевые слова: внешний баланс, импорт, комплексная оценка, потребление, производство, формирование, чистый экспорт.Under present-day conditions it is important to maximize the consumption of energy resources produced in Ukraine, in particular coal resources. It will contribute to solving several macroeconomic problems of Ukraine like raising the energy assurance level as a component of national security of Ukraine, improving the competitiveness of domestic enterprises and the trade balance of Ukraine. At the present stage of development the most popular energy resources are oil and natural gas which is conditioned by their high heating and ecological characteristics. At the same time the reduction of these resources, irregularity of their deposits and other objective factors make for consumption of local energy resources, in particular coal resources. It is defined that foreign energy balance is an index system that shows the demand-consumption ratio of an energy resource in a given period of time inside the country. A foreign energy balance model has been designed which includes calculation of the net export and makes it possible to clear up the modern tendencies that established in our country’s external economic relations of energy resources trade. It has been proved that the basic factor reducing the net export of energy resources is a great volume of imported natural gas though the trade balance of coal and peat operations is negative as well. A complex evaluation of production and consumption ratio of coal in Ukraine based on reduction coefficient to oil equivalent has been carried out which makes it possible to reveal the discrepancy between the volume of coal produced and the volume of coal consumed with its latter accumulation in Ukraine. The necessity of reducing the volume of coal import is proved. Keywords: foreign energy balance, import, complex evaluation, consumption, production, formation, net export

    On the relationship between travel time and travel distance of commuters. Reported versus network travel data in the Netherlands

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    This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and reported travel time. Reported travel times are usually rounded in multiples of five minutes. This calls for special statistical techniques. Ignoring the phenomenon of rounding leads to biased estimation results for shorter distances. Rather surprisingly, the distance as the crow flies and the network distance appear to be slightly better proxies of the reported travel time compared with the shortest network travel time as indicated by the route planner. We conclude that where actual driving times are missing in commuting research the other three indicators mentioned may be used as proxies, but that the following problems may emerge: actual travel times may be considerably higher than network times generated by route planners, and the average speed of trips increases considerably with distance, implying an overestimate of travel time for long distance commuters. The only personal feature that contributes significantly to variations in reported travel times is gender: women appear to drive at lower average speeds according to our data. As indicated in the paper this may be explained by the differences in the car types of male and female drivers (females drive older and smaller cars) as well as higher numbers of stops/trip chaining among women. A concise analysis is carried out for carpoolers. Car-pooling leads to an increase in travel time of some 17% compared with solo drivers covering the same distance. In the case of car poolers, the above mentioned measures appear to be very poor proxies for the actual commuting times

    Transport Modelling During Preparation of General Plans in Big Cities: Reasons and Challenges

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    Rapidly growing mobility of people in European cities attaches greater importance to the sustainable developmentconcept. The dynamics of European cities are however different. Cites such as Lithuanian, Slovakian and Polishones will rapidly increase traffic flows and car ownership at fast pace. Also in most of Western Europe, even if at lowerrates, private mobility is increasing. In some cities, however, car use and car ownership are finally decreasing, alsothanks to policies implemented. Of course, an increase of traffic flows poses problems in terms of street space, pollutionand liveability of cities. Sustainable integration of all kinds of transport into the urban development process is one ofthe most effective actions in the hands of city planners. The coordination between the planning of residential and businessdevelopment areas and the expansion of public transport and its hierarchical integration is however a difficult butnecessary exercise. Transport modelling tools, in particular, need important advancements to integrate transport andland use in simulations. This article analyses the main challenges in the use of transport models to support the constructionof city plans by means of two case studies of Milan and Vilnius. The analysis deals both with traditional aspects,such as the proper simulation of multimodal choices, the level of detail of zoning, the issues associated to the simulationof traffic management policies. Then, we will focus on two aspects still open: the integration of transport modelling andeconomic assessment or ranking of actions, and the inclusion of land use changes in the modelling

    Bereikbaarheid: perspectieven, indicatoren en toepassingen

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    In dit hoofdstuk geven we een overzicht van perspectieven op en indicatoren voor bereikbaarheid. Doel ervan is duidelijk to maken dat voor zowel onderzoek als beleid het van groot belang is goed aan to geven wat men precies onder bereikbaarheid verstaat, en dat de juiste keuze van bereikbaarheidsindicatoren voor zowel onderzoek als beleid van groot belang i

    Perceived risk of lock-in in the front-end phase of major transportation projects

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    Lock-in is defined as the tendency to continue with an inefficient decision or project proposal. The front-end phase is critical to project success, yet most studies have focused on lock-in in the implementation phase. Moreover, little is known about the way in which decision-makers perceive the risk of lock-in. In this paper we identify determinants of lock-in in the front-end phase and we reveal decision-makers’ perceptions of risk of lock-in. Our findings show that risk attitudes towards lock-in vary with the level of risk aversion. However, this is not sufficiently acute to drive the level of regret needed to avoid lock-in. This implies that decision-makers do not accurately assess the risk of lock-in and as such their risk perceptions are a mediating factor in the formation of lock-in. Based on escalation of commitment, path dependency, and prospect theory, the main contribution lies in providing a more comprehensive understanding of lock-in in the front-end phase

    A simple catch: Fluctuations enable hydrodynamic trapping of microrollers by obstacles

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    It is known that obstacles can hydrodynamically trap bacteria and synthetic microswimmers in orbits, where the trapping time heavily depends on the swimmer flow field and noise is needed to escape the trap. Here, we use experiments and simulations to investigate the trapping of microrollers by obstacles. Microrollers are rotating particles close to a bottom surface, which have a prescribed propulsion direction imposed by an external rotating magnetic field. The flow field that drives their motion is quite different from previously studied swimmers. We found that the trapping time can be controlled by modifying the obstacle size or the colloid-obstacle repulsive potential. We detail the mechanisms of the trapping and find two remarkable features: The microroller is confined in the wake of the obstacle, and it can only enter the trap with Brownian motion. While noise is usually needed to escape traps in dynamical systems, here, we show that it is the only means to reach the hydrodynamic attractor.“la Caixa” Foundation (ID 100010434), fellowship LCF/BQ/-PI20/11760014. The European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 847648
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