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1.
Y. Tao J. Dong X. Pan Y. Xiao J. Tu 《International Journal of Environmental Science and Technology》2017,14(12):2733-2744
The health risks presented by noxious vehicle emissions inside tunnels has been amplified due to the increasing use of roadway tunnels. Particularly, for adjacent roadway tunnels, vehicular emissions from the upstream tunnel can further deteriorate the air quality within the following tunnels. A scale vehicle tunnel model was designed to experimentally modelled the airflow and pollutants dispersion in contiguous roadway tunnels. The channelling effect on pollutants dispersion between adjacent roadway tunnels was studied, and factors such as ventilation speed, open road section length, traffic condition (e.g. car free, car running and traffic congestion) were considered. Pollutants mass flow rate ratio between downstream and upstream tunnels was calculated to evaluate the variation of the entrained pollutants amount. For the car free condition, pollutant can be easily entrained into the downwind tunnel when the gap distance between roadway tunnels decreased. For the car running condition with fixed tunnel gap distance, the traffic speed variation barely changed the pollutants mass flow rate ratio. Furthermore, evident influences on pollutants concentration were observed from continuous congestion and partial congestion. Lastly, numerical simulation using computational fluid dynamics approach was conducted for the car free scenario, and reasonably good agreements were found for pollutants concentration ratio compared with the experimental data. The results yielded from this study further quantified the relationships among different influential factors on the pollutants dispersion between roadway tunnels, and can contribute to an improved tunnel ventilation system design, especially for the downstream tunnel. 相似文献
2.
Croatia is located on the southeastern edge of Central Europe (Ruppert 1995), between the navigable Danube River and the Adriatic Sea, so that participates not only in continental traffic, but in the maritime and river traffic of Europe as well.Although the transit position of Croatia is very favorable, transportation itself has unfortunately not been developed in accordance with these advantages. This is a result of the social-economic, especially political, development of the region in the course of its history. Unfortunately, politics also influences the selection of transit routes in this part of Europe today. With the break-up of socialist states, particularly the former Yugoslavia, new states have appeared which are seeking their place in the European traffic network. Because of the momentarily uncertain political circumstances, the construction of some transit routes in Croatia have not been foreseen in international developmental plans for continental transit, despite the fact that they would be logically expected given the advantages of their position. 相似文献
3.
Globally, transport literature indicates a strong effect of land use on urban travel as people living in low density suburban areas tend to travel more by car than people living in high density urban areas. This is because in dense areas, public transport is organised more efficiently and travellers tend to travel shorter distances. However, this assertion is frequently based on locations with efficient integration of transport within the land use planning framework. In Ghana and many African countries, it remains unknown whether the effect of land use on urban travel is strong as reported in developed countries and elsewhere. This research examines the effect of land use on urban travel in Ghana using Kumasi, the second largest city in Ghana, as a case study. Simple questionnaire survey with urban residents, semi-structured interviews with agencies and secondary data analysis were used for this research. Results indicate negative effect of land use on urban travel as there has been increased congestion in all the major road arterials in the city resulting in difficulty in commuting using motorised transport. Findings further show a weak effect of land use on urban travel, as areas experiencing change of land use have poor locational accessibility. The paper recommends innovative ways of meeting the growing travel demand of residents in the city such as the development of a light rail and bus rapid transit systems to help ease congestion and improve public transportation. 相似文献
4.
Bernhard Butzin 《GeoJournal》1991,2(1):11-26
Within a typical process of urbanization several particularities can be noticed in the Helsinki region: The peninsular location does not allow a zonal expansion of the city. It has rather enforced a tight spatial sectoral expansion with specific problems of traffic and land use. The retarded industrialization has led to an unusually fast population increase without control until the 1960s.The rapid growth created a twofold problem: pressure of population versus inadequate housing, small residences versus high rents; consequently selective migration and small size families. The number of jobs rapidly increased and displaced the residential population of the inner city. This resulted in high traffic which neither the few main roads nor the public transport system of central Helsinki could cope with.These problems correspond to the essential tasks of urban planning: the bottle neck in housing construction has to be broken; the growth of jobs in the central city needs to be stopped as well as the displacement of the residential population. Decentralization, especially of the private tertiary and quartary sector may help. A system of central places within the region would diminish the commuting traffic. Transportation may be solved by a concept of growth points and growth axis along the railway lines.This grown concept of Helsinki should be thought over under the now foreseeable conditions of population stagnation. 相似文献
5.
Out of administrative control: Absentee owners, resident elk and the shifting nature of wildlife management in southwestern Montana 总被引：1，自引：0，他引：1
This paper describes the historical roots of an ongoing wildlife management dilemma involving decreasing opportunities for elk management via public hunting on private land in the context of an expanding elk presence on private land in southwest Montana. Our main focus is on the role of private ranchland in elk ecology, and the ability of land owners to set elk migration in new directions through cumulative decisions about hunting and tolerating elk. This takes elk management, traditionally the purview of the state, out of administrative control. We document connections between the region’s historical and emerging land tenure patterns, and analyze associated changes in hunter access. Elk numbers expanded rapidly in the Upper Yellowstone Valley at a moment of significant transition in ranchland tenure. New owners more interested in natural amenities than in livestock production encouraged the elk and discouraged hunting. This reinforced the spread of elk, and further weakened the ability of the state and other ranchers to manage elk (which interfere with livestock production in numerous ways). Though elk and cattle use the landscape in similar ways, elk became more effective agents of landscape change in a reflexive relationship with ideas of land that stress natural amenities over production. 相似文献
6.
Dr. Bernhard Butzin 《GeoJournal》1978,2(1):11-26
Within a typical process of urbanization several particularities can be noticed in the Helsinki region: The peninsular location does not allow a zonal expansion of the city. It has rather enforced a tight spatial sectoral expansion with specific problems of traffic and land use. The retarded industrialization has led to an unusually fast population increase without control until the 1960s. The rapid growth created a twofold problem: pressure of population versus inadequate housing, small residences versus high rents; consequently selective migration and small size families. The number of jobs rapidly increased and displaced the residential population of the inner city. This resulted in high traffic which neither the few main roads nor the public transport system of central Helsinki could cope with. These problems correspond to the essential tasks of urban planning: the bottle neck in housing construction has to be broken; the growth of jobs in the central city needs to be stopped as well as the displacement of the residential population. Decentralization, especially of the private tertiary and quartary sector may help. A system of central places within the region would diminish the commuting traffic. Transportation may be solved by a concept of growth points and growth axis along the railway lines. This grown concept of Helsinki should be thought over under the now foreseeable conditions of population stagnation. 相似文献
7.
由于受长期地表降水与排水下渗、前期施工、拆迁等加卸载作用及车辆交通荷载的扰动影响,城市拆迁场地土体的特性与处于原始地形地貌和地层分布的土体情况有所不同。目前尽管已经发表了大量黄土浸水试验的成果,但基本都是在原状黄土场地进行,而在这类扰动场地黄土中开展浸水试验的研究尚不多见。在兰州东岗轨道交通车辆段建设场地进行了累计观测时间超过100天的试坑原位浸水试验。结合室内土工试验和现场测试结果,讨论了该扰动场地黄土浸水产生沉降变形的特征。结果表明:该扰动场地浸水发生沉降变形的时间发展过程具有"缓慢增长-突增-趋于稳定"的特点,其总沉降也远小于既有原状黄土场地的实测结果,应理解为广义的浸水增湿湿陷,其变形包括压缩变形和湿陷变形两部分,二者比例近似为7:3;前期扰动导致的较低的孔隙比和试坑开挖造成的卸荷是其总变形量较小的原因,但是其浸水沉降变形增长过程中突增的湿陷变形和土层空间分布不均匀引起的差异沉降值得引起注意。研究结果对于进一步加深对黄土湿陷变形与水稳定性的理解,选择扰动场地黄土地基处理和防排水措施具有一定的参考价值。 相似文献
8.
A. K. Verma Manish Kumar Jha Srinivas Mantrala T. G. Sitharam 《Geotechnical and Geological Engineering》2017,35(5):1953-1966
Rapid growth of urban population in Indian cities have led traffic congestion leading to demand for scientific utilization of underground space. Immediate underground level and deep level underground below the major arterial roads are the sustainable spaces available for meeting the demand of the future traffic/transport. Due to recent increased transit activities it has become one of the soft targets by terrorists or prone to catastrophic accidents in recent years which have increased the importance of rock structures study under explosive loading. In this paper, the response of a underground metro tunnel subjected dynamic loads have been investigated including explosive capacity (30 kg TNT), ground characteristics, liner thickness and blast pressure characteristics. Blast pressure representing CONWEP air blast loading model with positive over pressure phase was applied to lining of tunnel. A three dimensional explicit finite element method was used to analyze dynamic response and damage in twin tunnels of underground metro. It is found that liner of thickness 28 cm will start deforming at the explosive loading of more than 65 kg TNT. 相似文献
9.
Ian Alexander 《Geoforum》1980,11(3):249-275
A case study of office dispersal options in Sydney, Australia is presented within a Planning Balance Sheet Framework. Two dispersal options, one involving a limited number of large subcentres, the other a large number of smaller subcentres are examined. It is shown that both options are likely to result in considerable work-journey time savings for employees in relocated offices (particularly clerical and female workers) and considerable improvements in job access for many suburban residents. Overall, however, the large subcentre option appears to offer greater net benefits to both office employees and relocated organizations. Yet both options are likely to generate high external costs in terms of suburban road congestion, increased energy consumption, financial losses to public transport operators, and inequities of access to captive public transport users. These problems could be avoided if the government were to embark on a programme of upgrading public transport services and restricting car usage to the point where the majority of suburban commuters used public transport. This would involve considerable public expenditure, which is unlikely to be forthcoming in the present economic climate. But without such a programme, a policy of office dispersal would create more problems than it would solve. 相似文献
10.
隧道等洞室开挖后,其周边通常会产生许多贯穿裂隙,直接影响到围岩稳定。研究贯穿裂隙岩体的强度及其破坏方式对于围岩加固等具有重要意义。基于库伦强度准则,通过建立数学模型,利用 - 坐标系下裂隙面和岩块的强度曲线位置关系研究了贯穿裂隙岩体强度和破坏方式。探讨了贯穿裂隙岩体强度与裂隙面的倾斜角、黏聚力和内摩擦角及岩块的黏聚力和内摩擦角间的关系,得到了贯穿裂隙岩体破坏方式的相关判据。数值算例表明该模型能够预测在任意最小主应力下贯穿裂隙岩体的强度和任意加卸荷路径下岩体破坏方式,与传统的利用 - 坐标系下裂隙面、岩块的强度曲线和摩尔应力圆的位置关系来判断岩体破坏方式的方法相比,该模型的方法更简便有效,结论更直观,能更好地为工程设计和岩体加固提供技术支撑。 相似文献
11.
Dragos Toma-Danila 《Natural Hazards》2018,93(1):97-111
Through this paper we propose and test a GIS framework that addresses the issue of seismic risk due to urban road network failure. The approach relies on full GIS integration, on Monte Carlo simulations for generating potentially disrupted network configurations, considering also the damage probability due to direct earthquake implications, and on traffic considerations (both in typical and post-earthquake situations). The damage probability can be obtained using fragility functions for critical structures like bridges and tunnels or by determining empirically the possibility of affected buildings to generate debris leading to road obstruction. Multiple performance indicators such as travel time and distance under various conditions are combined, in order to quantify the risks inflicted by dysfunctionalities in the emergency intervention process. The framework considers at the same time temporal and spatial dimensions, being able to cope with traffic dynamics or reconfigurable network configurations. The ArcGIS Network Analyst Module is used for model integration, and full city scale analysis is performed in order to test the capabilities. Bucharest (capital of Romania) is selected for the case study; this 2 million inhabitant city is one of the most endangered in Europe, due to earthquakes that occur in the Vrancea Area, at intermediate depth, with moment magnitudes > 7, but also due to the vulnerable building stock. Beside this, it is one of Europe’s top cities when it comes to traffic congestion. The results of the study provide initial insights on the deficiencies of the city’s road network and connectivity limitations, showing the high impact of road obstructions and traffic congestion on intervention times, for ambulances and firefighters, in case of an earthquake. 相似文献
12.
R. K. Mishra M. Parida Ph.D. S. Rangnekar Ph.D. 《International Journal of Environmental Science and Technology》2010,7(4):737-750
Due to increasing motorization, construction of flyovers and growth in transport network, the noise level has exceeded the prescribed limits in many Indian cities. The health implications of high noise levels are being identified as hypertension, sleeplessness, mental stress, etc. Due to this adverse effect of noise level, it is essential to assess the impact of traffic noise on residents and road users. This research is an effort to quantify and analyze the traffic noise emissions along bus rapid transit corridor in Delhi. Field measurements were carried out to understand and assess various aspects of the impact of bus rapid transit system corridor on land use and social lives of residents and road users. The present analysis presents the comparison between observed and predicted noise level at selected corridors and also describes the mitigatory measures to overcome such type of traffic noise pollution through design of noise barrier along the road and motivate people towards the use of public transport system. 相似文献
13.
Through this paper we propose and test a GIS framework that addresses the issue of seismic risk due to urban road network failure. The approach relies on full GIS integration, on Monte Carlo simulations for generating potentially disrupted network configurations, considering also the damage probability due to direct earthquake implications, and on traffic considerations (both in typical and post-earthquake situations). The damage probability can be obtained using fragility functions for critical structures like bridges and tunnels or by determining empirically the possibility of affected buildings to generate debris leading to road obstruction. Multiple performance indicators such as travel time and distance under various conditions are combined, in order to quantify the risks inflicted by dysfunctionalities in the emergency intervention process. The framework considers at the same time temporal and spatial dimensions, being able to cope with traffic dynamics or reconfigurable network configurations. The ArcGIS Network Analyst Module is used for model integration, and full city scale analysis is performed in order to test the capabilities. Bucharest (capital of Romania) is selected for the case study; this 2 million inhabitant city is one of the most endangered in Europe, due to earthquakes that occur in the Vrancea Area, at intermediate depth, with moment magnitudes > 7, but also due to the vulnerable building stock. Beside this, it is one of Europe’s top cities when it comes to traffic congestion. The results of the study provide initial insights on the deficiencies of the city’s road network and connectivity limitations, showing the high impact of road obstructions and traffic congestion on intervention times, for ambulances and firefighters, in case of an earthquake.
相似文献14.
R. Helle 《GeoJournal》1977,1(3):55-60
Conclusions Transport via the Siberian railway in trade between West Europe and Japan is clearly advantageous compared with sea transport. Whether the Siberian transport route is productive for the Soviet Union measured by Western standards is difficult to say. Some Western experts at least have expressed their doubts.It is known that some industrial western market-economy countries have been asked to invest in the construction of the Baikal-Amur railway in return for promised supplies of earth gas and oil. The development of the Siberian transit transport route may also be taken as a sign of an opening up of the Soviet Union to Western countries in a wider sense, and her growing interest in forming trade relations with the West.From the start the Siberian transit transport route was intended, in addition to the Soviet's own transport needs, for goods traffic between West Europe and Japan. Since then connections have been made with Hong Kong and the Philippines. In the future connections via Siberia may be made with Taiwan, South Korea and other East Asian countries and Australia. Thus the international significance of the Trans-Siberian railway in trade between the Far East and Europe will increase considerably. This will mean that the Soviet officials will be faced with what may prove a difficult decision concerning the growing demands of international transit traffic in relation to the increasing domestic transport on the same rail network.It seems likely that the Soviet Union will obtain an increasing proportion of the foreign exchange she needs from this growth in transport. In 1975 this sum was estimated at US $ 150.000.000. With the development in traffic the Soviets are also obtaining and developing new technological know-how. The biggest losers are the shipping lines belonging to the Far-Eastern Freight Conference. They are mainly from Western countries, but there are also members from Poland and East Germany who will lose freights to the Siberian transport route. 相似文献
15.
Nicholas Blomley 《Geoforum》2005,36(3):281-296
Legal spaces are said to be a crucial materialization of law, serving to communicate legal meaning and, in so doing, helping to produce a liberal-legal consciousness. Given its centrality to legal ordering and liberal ideology, the spatial manifestation of the public-private divide, especially when related to property, would appear to be particularly important in this regard. Public and private are assumed to be both mutually exclusive and exhaustive. Drawing upon empirical research conducted in a neighbourhood in Vancouver, Canada, I argue that spatial and legal categories such as public and private may be more fluid than one might suppose. While the public/private divide is clearly powerful, and informs much policy and governmental action, it is not necessarily the case that it has the purchase on everyday life that some scholars have suggested. People may live in more complicated and overlapping worlds when it comes to supposedly determinate categories such as property. 相似文献
16.
David Correia 《Geoforum》2010,41(1):66-73
Beginning in the 1990s, private ownership in Maine forestland shifted from a number of corporate owners to a patchwork of timber investment management organizations (TIMOs) and real estate investment trusts (REITs). This transformation reflected restructuring trends in the paper and pulp industry. During this same period, forest certification increased to levels that today make Maine one of the most certified states in the United States with nearly 8 million acres certified by one of a number of certifying entities. This paper examines the contradictory tensions of these trends. Specifically, the conservation goals of certification are undercut by increased investment in timber resources characterized by new financial instruments focused on return on investments. The increased use of first-party, industry-based certification suggests that the antagonisms between capital and conservation are being resolved in ways that undermine the purported conservation goals of forest certification standards. 相似文献
17.
Natural Hazards - In Kuwait, the transport sector is facing a daily traffic congestion pandemic. The traffic congestion is significantly influencing the economy and obstructing the development and... 相似文献
18.
Evan McKenzie 《GeoJournal》2006,66(1-2):89-102
Common interest housing (CIDs), which includes nearly all gated communities as well as non-gated but privately governed neighbourhoods, has become the predominant form of new housing construction in America. Optimistic early assessments that CIDs would prove to be more efficient alternative to municipalities are confronted by the fact of high levels of conflict and litigation, which are proving costly to residents as well as local governments. These conflicts are often highly publicized in the press, leading to concerns in the real estate industry that the demand for such housing could be jeopardized. The conflicts arise from having unpaid, untrained volunteer directors carrying out what were once municipal government functions, and concern financial issues as well as alleged abuses of power by association boards. In response to some of these concerns, across the nation, small but vocal ant-HOA owners groups are organizing, using the internet as their medium and gaining attention from the press. A consensus is emerging that the law governing private communities needs major changes, and different approaches are proposed or being implemented in several states. This paper examines these emerging regulatory trends and offers an assessment of their prospects. 相似文献
19.
20.
某大型地下洞室群围岩稳定性分类研究 总被引：17，自引：5，他引：12
根据地下洞室群的特点 ,选取岩体质量综合级别、块体状况、开挖位移及破坏区、岩爆烈度四因素为分类指标 ,建立了大型地下洞室群围岩稳定性分类体系。针对不同稳定性等级 ,提供了相应的开挖方式和支护处理建议。最后 ,运用该分类体系对某地下洞室群的主厂房进行了分析评价。 相似文献