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1.
From roadkill to road ecology: A review of the ecological effects of roads   总被引:1,自引:0,他引:1  
Transportation infrastructure affects the structure of ecosystems, the dynamics of ecosystem function, and has direct effects on ecosystem components, including their species composition. Clearly, the construction of transport lines results in the direct destruction and removal of existing ecosystems, and the reconfiguration of local landforms. However, transportation systems, and more specifically, roads, have a wide variety of primary, or direct, ecological effects as well as secondary, or indirect, ecological effects on the landscapes that they penetrate. The effects of roads can be measured in both abiotic and biotic components of terrestrial and aquatic ecosystems. The nature of road systems as network structures renders vast areas of the landscape as road-affected, with small patches of isolated habitat remaining beyond the ecological influence of roads. The increasing attention of scientists to the unintended ecological effects of roads has resulted in the emergence of the science of “Road Ecology,” marked with the publication of a multi-authored volume, Road Ecology: Science and Solutions, in 2003.  相似文献   

2.
Freight modal shift from road to rail is a potential means by which the negative environmental and social impacts of transport can be reduced. This paper explores recent supply chain changes and assesses their impacts on the mode choice decision-making process, specifically addressing the implications for the use of rail. Despite many of the identified changes effectively making the use of rail more difficult, considerable evidence has been found of the potential for rail to attract new traffic. Much of the identified potential is unlikely to materialise, however, without improvements in rail network capability and capacity and a greater customer focus from rail freight operators.  相似文献   

3.
Floods are becoming more frequent and the magnitude of direct consequences, relating to destruction of critical infrastructure and loss of life, has highlighted the importance of flood management. This study proposes a methodology for quantifying the impact of predicted and historic flood events on emergency services. The approach moves beyond simple flood inundation mapping by accounting for the relationship between flood depth and vehicular speed. A case study is presented for Calgary, Alberta, where the depths of a predicted 100-year flood and a historic 2013 flood event are modeled. The methodology applies geographic information systems to flood depth mapping, utilizing digital elevation models, flood extents, and hydrological data. Flood depths are then assigned to links comprising the road network, where the maximum vehicle speed is calculated as a function of the standing depth of water on a link. The flooded network is used to derive service areas for several types of emergency services (emergency medical services (EMS), fire, and police), following targeted response times. The results locate and quantify the residential and work populations that no longer meet the targeted response times. During both flood scenarios, EMS is found to have the greatest reduction in accessibility, with 23% and 47% of residents and workers, respectively, not served. Fire services are seen to be more resilient with only 3% and 9% of residents and workers, respectively, not served. The results for police services are similar to fire services. However, the former have a greater range of response times, meaning these areas represent those that are completely isolated during both flood events. Overall, the integrated methodology quantifies vulnerable populations on a partially degraded network, the results of which can be used to develop evacuation plans and emergency response strategies.  相似文献   

4.
This paper seeks to contribute to ongoing debates around the politics of hybrid mobilities, smart cities, surveillance capitalism and mobility fixing. Based on a set of qualitative interviews with key stakeholders and secondary sources, the paper uses the emergence of dockless public bike sharing in Shanghai between 2016 and 2018 as its case study. In order to explain the emergence of dockless PBSS and illustrate our contention that this system seeks to create surplus value from the work of mobility (in this case cycle commuting), we examine the processes of valorisation that have occurred in order to both position PBSS as a worthy activity (and therefore remunerate participants affectively) and produce use values for the data generated by users. In doing so we also highlight the ways in which these processes of valorisation seek to ensure that the mobility work of users is not aligned with the products of that labour in order to avoid calls for this mobility work to be remunerated as wage labour (which would reduce any surplus value extraction). Ultimately we argue that these processes of valorisation are not only invasive, but exclusionary in that they prioritise select aspects of social practice that address matters of (governmental) concern, rather than a more rounded interpretation. We argue that there is an urgent need to recognise mobility practices beyond registers that simply prepare the ground for their marketisation.  相似文献   

5.
This paper reschedules train services on a double-track high speed railway in a disrupted situation, where one track of a segment is temporarily unavailable. We have to decide the sequence of train services passing through the blocked segment, the arrival and departure time of each train service at each station, and the canceled train services. Three practical train rescheduling strategies are explicitly compared and formulated by three MILP models. The uncertain duration of the disruption is handled. A rolling horizon approach is applied to solve our models. The models are tested on a real-world instance of the Beijing-Shanghai high speed railway.  相似文献   

6.
Passengers' dissatisfaction with service quality is one of the crucial factors affecting the market share loss of airlines. This study aims to find out how airlines become capable of satisfying their passengers by considering the diversity of pre-purchase expectations. Therefore, the study proposes a novel model for clustering air passengers to identify passengers with similar expectations. Thus, the passengers' expectations of the service quality attributes in each cluster were measured and converted into quantitative degrees of customer satisfaction by applying the Kano model. Finally, Importance-Satisfaction Analysis (ISA) was employed to finding that which service quality indicators fall into the “Keep up the proper work”,” Concentrate here”,” Possible overkill”, and “Low priority” category for eliciting applicable marketing strategies.  相似文献   

7.
During the past decade, air passenger service in the United States has been exposed to numerous carrier bankruptcies, antitrust investigations, mergers, labor problems and a massive increase in competition. These internal elements, combined with the rising costs of fuel and the threat of terrorism combine to make a relatively uncertain air travel landscape for both passengers and operators. Moreover, these dynamics have generated significant geographical shifts in airline route structures and airports serviced by commercial carriers. These factors, combined with increasing levels of consumer access to fare and routing information, have altered the landscape of air travel accessibility in the United States. The purpose of this paper is to examine issues of consumer air travel accessibility through an analysis of three critical measures: flight segments, flight time and ticket costs. In addition, a typology of air passenger accessibility is generated for the 156 busiest commercial airports in the United States using these three measures. Results suggest significant local and regional biases in time and cost, relative to distance, for many US markets.  相似文献   

8.
An accurate estimation of airport catchment area enables airlines and airport operators to make informed decisions and to target potential markets precisely. This study uses the state of Indiana as a case study to estimate traffic leakage from the local airport, Indianapolis International Airport (IND), to two large hub airports in Illinois, the neighboring state of Indiana, namely Chicago O'Hare International Airport (ORD) and Chicago Midway International Airport (MDW). By using a decision making model that considers flying cost and access cost, this study simulates from local passengers' perspective which origin airport delivers the most cost effective flight itinerary. Using the top 20 routes of IND in 2018 as model inputs, the catchment area of two Chicago based airports in Indiana with variable coverage is plotted for different traveling scenarios. The analysis shows that an airport catchment area is sensitive to location, service level and traffic volume of competing airports nearby, as well as purpose of travel (business or leisure), number of travelers in a group (single, couple, family or multiple), length of trip, destination (domestic or international), preference of airlines (network carrier or budget carrier), and frequent flyer program status (premier member or general member). These findings could be valuable to all three aforementioned airports as well as airlines serving these airports when allocating operational and marketing resources. More importantly, this study creates a generic model that could be used by virtually any airport to estimate scenario-based catchment area using readily available itinerary and spatial data without resorting to expensive passenger surveys.  相似文献   

9.
This paper extends research on urban form and travel behavior beyond adult travel by examining teen travelers aged 13–19 in the Greater Toronto Area. Data from the Transportation Tomorrow Survey (TTS) survey are used to study four main research questions: (1) How has teen mode choice changed from 1986 to 2006? (2) How do these choices vary as teens transition from the 13–15 age group to being of driving age (16–19)? (3) How do these choices vary across the different urban and suburban regions of the GTA? (4) What are some of the differences between teen travel and adult travel? Results show that in general, active transportation has decreased, while auto-passenger mode shares have increased across the region. The younger group walks more and the older group takes transit more for both school and discretionary travel. Jurisdictions with better transit supply and orientation have higher transit mode shares for school trips, but discretionary trips have very low transit mode shares. Walk mode shares for both school and discretionary travel are similar across all jurisdictions, regardless of whether they are urban or suburban. In contrast to adult travel in the GTA, built form characteristics and transit supply do not appear to have a direct relationship with teen mode choice. Urban form appears to exert an indirect influence on teen travel.  相似文献   

10.
Despite evidence showing the spatial nonstationarity of the determinants of bike activity, very few studies have addressed the phenomena, probably due to the limited sample size of the traditional count data. To address this gap, this study demonstrated the applicability of Strava bike activity data by developing a geographically weighted Poisson regression (GWPR) model that can reveal how the influence of socioeconomic and land-use factors vary across a region. The city of Austin was selected as a case study, and Strava bike volume was gleaned from 1494 intersections. The representativeness of the Strava data was first examined by comparing those data with the video-based actual bicycle volume data from 43 intersections in the study area. Despite the high deviation in several locations, Strava volume exhibited moderate linear relationships with actual volume. The GWPR model developed in this study outperformed the traditional global model and revealed significant spatial variability of nine variables related to age, income, education, transit stops, hub locations, offices, schools, trails, and sidewalk facilities. Notable spatial variations on bike activity were observed across the study area in terms of magnitude, direction, and significance of the impact for all model variables. The analysis and discussion offer guidance to practitioners and policy makers in tailoring policies and programs that consider the spatial context. The study also provides insights for understanding the potential use of crowdsourced data in examining bike activity, especially when resources are limited.  相似文献   

11.
The paper presents a random utility-based measure of accessibility to explain the first-mile issue in urban transit. A discrete access stop/station location choice model is used to calculate the expected maximum utility of transit access choices as the measure of the proposed access to transit measurement approach. It captures the effects of changes in various personal, sociodemographic, transportation and land-use variables on access to urban transit that are overlooked by conventional approaches of accessibility measurements (count-based cumulative opportunities measures and gravity-based measures). The proposed accessibility to transit measurement approach is empirically measured for the Greater Toronto Area and is integrated into an operational tool programmed in a GIS-based traffic assignment software, TransCAD 7.0. This allows comparing it to the conventional measures, and the results reveal that the conventional measures tend to over-estimate access to transit.  相似文献   

12.
The purpose of this research is to compare salient approaches for identifying the patterns of college students' information search behaviours while preparing for their spring break trips. Comparing four different prominent constructs (i.e. past experience, prior knowledge, involvement and a concept of specialisation combining those three variables), the results of the study indicate that involvement and the specialisation concept have more distinctive results than the others in terms of measurement of travellers' perceived usefulness of information sources and the importance of information content. In addition, the different groups assigned different priorities for usage of main information sources. As a result, involvement and the specialisation concept appear to provide more distinctive clarification for identifying the information search behaviours of spring break travellers. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

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