Results 1 - 10 of 386
Results 1 - 10 of 386. Search took: 0.029 seconds
|Sort by: date | relevance|
[en] In his famous novel The Caves of Steel, Isaac Asimov imagined a public transportation system based on a series of parallel moving walkways accelerating pedestrians progressively toward a high-speed central lane which continuously carries the crowds of the gigantic cities of our future Earth. In this paper, it is shown that the user of this system would face an interesting optimization problem, namely the design of the path which would minimize the travel time from one place to another. This problem is solved with the classical techniques of Lagrangian mechanics. (paper)
[en] The concept of smart city gives an excellent resolution to construct and develop modern cities, and also demands infrastructure construction. How to build a safe, stable, and highly efficient public transportation system becomes an important topic in the process of city construction. In this work, we study the structural and robustness properties of transportation networks and their sub-networks. We introduce a complementary network model to study the relevance and complementarity between bus network and subway network. Our numerical results show that the mutual supplement of networks can improve the network robustness. This conclusion provides a theoretical basis for the construction of public traffic networks, and it also supports reasonable operation of managing smart cities. (rapid communication)
[en] This article described different traffic congestion schemes that cities around the world have adopted to ease traffic grid-lock. Congestion fees that discourage road use involve assigning a price to a road based on the demand for using that road. A weekday congestion fee which was imposed on drivers in the city of London in 2003 resulted in a 30 per cent drop in vehicular traffic in the city centre. The pricing structure was independent of vehicle type, distance travelled or time of day. The successful scheme is credited with an increase in cycling and public transit ridership as well as a decrease in accidents and air pollution without hindering business within the congestion zone. However, the effectiveness of congestion fees in North America is questionable. Although San Diego's high-occupancy toll lanes have helped reduce congestion and pollution because the revenue raised is invested in public transportation, objections have been raised regarding plans to implement congestion fees in San Francisco and New York city centres because doing so would prevent those with low incomes from driving in the city. London has responded to such challenges by putting all net revenues derived from the fees back into public transportation. Similar measures were taken in Stockholm, Sweden where massive improvements were made to its transit system prior to introducing congestion fees to avert criticism. In order for congestion fees to be effective and gain public approval, there should be clear objectives that include demand management, good transportation alternatives, revenues that go to public transit and a simple pricing system that uses proven technology. The cumulative annual cost of congestion in 9 urban centres in Canada ranged from $2.3 billion to $3.7 billion in 2002 according to Transport Canada. Analysts have cautioned that congestion schemes would be difficult to duplicate in North American cities that are highly dependent on automobiles. However, the authors emphasized that this should not deter Canadian municipalities from taking action to reduce grid-lock, particularly when there are lessons from which to learn. 2 refs., 1 fig
[en] The aim of this paper is to investigate the use of different self-reported measures for assessing the human response to environmental vibration from the construction of an urban LRT (Light Rapid Transit) system. The human response to environmental stressors such as vibration and noise is often expressed in terms of exposure–response relationships that describe annoyance as a function of the magnitude of the vibration. These relationships are often the basis of noise and vibration policy and the setting of limit values. This paper examines measures other than annoyance by expressing exposure–response relationships for vibration in terms of self-reported concern about property damage and acceptability. The exposure–response relationships for concern about property damage and for acceptability are then compared with those for annoyance. It is shown that concern about property damage occurs at vibration levels well below those where there is any risk of damage. Earlier research indicated that concern for damage is an important moderator of the annoyance induced. Acceptability, on the other hand, might be influenced by both annoyance and concern, as well as by other considerations. It is concluded that exposure–response relationships expressing acceptability as a function of vibration exposure could usefully complement existing relationships for annoyance in future policy decisions regarding environmental vibration. The results presented in this paper are derived from data collected through a socio-vibration survey (N = 321) conducted for the construction of an urban LRT in the United Kingdom. - Highlights: • The human response to construction vibration is assessed in residential environments. • Exposure–response relationships are generated based on survey and semi-empirical vibration estimation. • Annoyance, concern and acceptability are compared as response measures. • Concern and acceptability are viable measures complementing annoyance.
[en] Highlights: • We propose three light rail scenarios, each covering a specific landscape structure to curtail private vehicle-driven urban sprawl in the Flemish rhombus. • We used the participatory multi-actor multi-criteria analysis (MAMCA) to assess the social, economic and environmental impact of alternative light rail scenarios. • We discuss catalyst measures to comply with the identified drawbacks of the proposed scenarios. - Abstract: Rail transit is generally acknowledged as an alternative transport mode in contributing towards sustainable mobility. In addition to minimising negative externalities, rail transit has sustainable land-use opportunities to integrate transport- and spatial planning. The objective of this paper is to determine the impact of integrative light rail scenarios and their ability to curtail private vehicle driven urban sprawl in the Flemish rhombus. The paper proposes three light rail scenarios: an infrastructural scenario; tramification scenario; and spatial rail scenario, each covering a specific landscape structure to reorganise the dispersed spatial environment in Flanders in the long-term. We used the participatory multi-actor multi-criteria analysis (MAMCA) which incorporates the objectives of all involved stakeholders to assess the impact of the scenarios. The infrastructural alternative scenario gained most support among the involved stakeholders, on the grounds of improved multimodality, enhanced user amenities, reduced implementation costs, moderated greenhouse gas emissions and mitigated infrastructural barrier effects. Despite the merits of the infrastructural scenario in terms of stakeholder objectives, few possibilities are included to elaborate upon sustainable land-use development. In response to the low performance of this assessment criterion, catalyst measures are discussed to support the implementation
[en] Given the difference between peak and off-peak occupancy rates in public transport, emissions per traveller kilometre are lower in the peak than in the off-peak period, whereas the opposite pattern is observed for cars. It is argued that it is much more fruitful to analyse environmental effects in marginal terms. This calls for a careful analysis of capacity management policies of public transport suppliers that are facing increased demand during both peak and off-peak periods. A detailed analysis of capacity management by the Netherlands Railways (NS) revealed that off-peak capacity supply is mainly dictated by the demand levels during the peak period. The analysis included the effects of increased frequency and increased vehicle size on environmental impacts, while environmental economies of vehicle size were also taken into account. The main conclusion is that the marginal environmental burden during the peak hours is much higher than is usually thought, whereas it is almost zero during the off-peak period. This implies a pattern that is the precise opposite of the average environmental burden. Thus, an analysis of environmental effects of public transport based on average performance would yield misleading conclusions
[nl]Aangezien de bezettingsgraad van het openbaar vervoer in de spits hoger ligt dan daarbuiten zou men verwachten dat spitsreizigers minder vervuilen dan dalreizigers. In deze bijdrage wordt aangetoond dat dit in elk geval voor de trein niet opgaat. De reden hiervan is dat een extra treinreiziger in de spits leidt tot de inzet van extra capaciteit (meer of langere treinen) die ook buiten de spits wordt ingezet. Dit betekent dat een extra treinreiziger buiten de spits niet leidt tot de inzet van meer capaciteit: er is dan immers ruimte genoeg in de treinen. De marginale milieukosten van treinreizigers buiten de spits liggen dus dicht bij nul. Voor deze analyse is het onderscheid tussen gerniddelde en marginaie kosten essentieel. Een ander belangrijk concept waarmee in de analyse rekening wordt gehouden betreft het bestaan van milieu-schaalvoordelen: per zitplaats vervuilen kleine voertuigen meer dan grote. De conclusie is dat NS in overweging zou moeten nemen om capaciteitsplanning en prijszetting in sterkere mate af te stemmen op de vraag. Dit is niet alleen goed voor het milieu maar zou ook gunstige bedrijfseconomische effecten kunnen hebben
[en] Arguments for and against the highly controversial levy approved by Translink, the transportation authority in Greater Vancouver, are discussed. This highly controversial plan will cost car owners in the Greater Vancouver Regional District up to $120 per year for transportation improvements to roads, public transit and bicycle paths. Supporters of the levy contend that divisive as the levy may be, it is a bold first step towards a user-pay system. The GVRD transportation system is badly in need of improvement and the levy is a quick and temporary way to finance the necessary work. However, even supporters of the scheme suggest that the levy should not be seen as the final solution. Instead, they urge Translink to move towards a usage-pay system, including a fuel tax, combined with road and bridge tolls. A pay-as-you-go system would encourage residents to drive less, or to drive more fuel-efficient vehicles. Regardless of how the public reacts to the levy system, Translink should commit to building a more equitable system to pay for the transportation improvements needed by the region
[en] In most countries with greenhouse gas emission reduction commitments, transportation has been relatively spared, thus, far in the targeting of reduction obligations, owing to the supposedly high marginal cost. With the prospect of tightening reduction targets, pressure is, however, mounting to address transportation more seriously in the near term and not to rely solely on medium to long-term breakthroughs of alternative fuel technologies. This means stricter policies at the demand side of the mobility market. In addition to fiscal and spatial policies, cap-and-trade systems have been put forward as a new option that deserves serious consideration. This paper reviews the possibilities and pitfalls of such a system applied to passenger transport. Key concerns are the transaction costs of the system and trade-offs between transaction cost and equity effects. A simple system with low(er) transaction cost is more likely to invoke politically sensitive equity effects. On the basis of the recent upsurge in monitoring and feedback studies, one may also conclude that the organisation and tailoring of the information interfaces for the household/traveller requires still elaborate study and testing.
[en] The profits made by the six main oil companies (ExxonMobil, Shell, BP, Chevron, Philips and Total) reached 121 billion US$ in 2005, i.e. two times the gross domestic product of a country like Bulgaria. The beneficiaries of these profits are mainly the shareholders while a small part only is reinvested by oil companies in production capacities (the lack of refining capacities would be responsible for a third of the rise of petroleum products price). Considering the recent increase of automotive and space heating fuels price, this situation appears as neither legitimate, nor conformable with the general interest. The aim of this proposal of law is the establishment of a tax on excessive profits of oil companies. This tax would contribute to reduce the petroleum dependence of France and to prepare the French economy and society to the 'after-petroleum' era (development of collective transport systems, financing of research on alternate energy sources). (J.S.)
[en] Highlights: • An integrated life cycle approach is used to study Urban Transport Metabolism (UTM). • A selection of different material, energy and environmental assessment methods is synergically applied. • The study is based on an accurate inventory of infrastructure, machinery and operative resource costs. • Results show that the different methods provide much needed insight into different aspects of UTM. • Innovative Bus Rapid Transport shows better resource and environmental performance than Normal Bus Transport system. - Abstract: An integrated life cycle approach framework, including material flow analysis (MFA), Cumulative Energy Demand (CED), exergy analysis (EXA), Emergy Assessment (EMA), and emissions (EMI) has been constructed and applied to examine the energy efficiency of high speed urban bus transportation systems compared to conventional bus transport in the city of Xiamen, Fujian province, China. This paper explores the consistency of the results achieved by means of several evaluation methods, and explores the sustainability of innovation in urban public transportation systems. The case study dealt with in this paper is a Bus Rapid Transit (BRT) system compared to Normal Bus Transit (NBT). All the analyses have been performed based on a common yearly database of natural resources, material, labor, energy and fuel input flows used in all life cycle phases (resource extraction, processing and manufacturing, use and end of life) of the infrastructure, vehicle and vehicle fuel. Cumulative energy, material and environmental support demands of transport are accounted for. Selected pressure indicators are compared to yield a comprehensive picture of the public transportation system. Results show that Bus Rapid Transit system (BRT) shows much better energy and environmental performance than NBT, as indicated by the set of sustainability indicators calculated by means of our integrated approach. This is because of the higher efficiency of such modality (less affected by traffic, higher vehicle occupancy, suitability for large distance transportation). The study suggests that the higher economic and resource investments performed in order to provide dedicated roads, more modern transport technology and higher speed, translated into a better use of resources and lower environmental pressure, also because of the attraction of an increased number of passengers, who would have otherwise used car transportation modalities. This study also provides a clear evidence that more than one criterion is needed to address a fully reliable and sustainable urban transportation policy. An integrated approach is therefore suggested to support decision making in the presence of complex systems and different kinds of concerns to be taken into proper account.