首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 406 毫秒
1.
This paper discusses how various aviation infrastructure service providers have dealt with the fall off in airline traffic following the terrorist attacks in the US on September 11th. It shows that these organizations have relatively high fixed costs and low incremental costs for providing services. As such, small changes in traffic have large impacts on revenue because revenues are generally proportional to activity. However, because of the high component of common and fixed costs, airport and ATS provider costs do not change in proportion to activity. When traffic declines, revenue shortfalls can arise because most airport and ATC systems operate on a simple cost recovery basis. The responses to the events of September 11th have also caused substantial increases in security costs. To the extent these costs are passed forward to system users, they will increase the price of travel and impact patronage further. Airlines also have substantial fixed capacity costs. The declines in traffic are often felt as an erosion of yields and fares as carriers seek to maintain traffic loads for the capacity they are going to operate. In general, the ability to pass along cost increases from providers to airlines or from airlines to passengers depends on relative supply and demand elasticities. Because infrastructure provision is often a monopoly, and the demand for airline services is price elastic, we suggest that most of the cost increases will be borne by the airlines. We also suggest that short-haul flights will be most severely impacted because the fees and taxes are a larger proportion of the fare for these flights. We also examine the extent to which additional infrastructure costs imposed on operators may exacerbate the downturn in their traffic.  相似文献   

2.
Accessibility is not a static feature because it is affected by a large number of factors, such as changes in transport infrastructure, the spatial distribution of human activities, and their interdependence. In this study, we examine the role of location quotient-based travel costs as the travel impedance function in accessibility measurement to better capture accessibility changes over time. The travel impedance function is one of the most widely studied aspects of accessibility. In most studies, travel impedance is determined by a negative exponential function in the travel cost assessment of the accessibility measure as a means to incorporate the distance decay effect. Here, we apply an accessibility index that uses location quotient-based travel costs and an accessibility measure with simple travel costs in order to test the proposed theory. The results of the two methods vary considerably. The location quotient method is discussed in detail, including its potential advantages for measuring accessibility changes. We argue that the location quotient-based travel cost is an appropriate method for determining the travel impedance function in accessibility measurements, especially for analyzing accessibility changes.  相似文献   

3.
Health care accessibility is a vital indicator for evaluating areas where there are medical shortages. However, due to the lack of population data with a satisfactory spatial resolution, efforts to accurately measure health care accessibility among older individuals have been hampered to some extent. To address this issue, we attempt to measure accessibility to health care services for older bus passengers in Nanjing, China, using a finer spatial resolution. More specifically, based on one month's worth of bus smart card data, a framework for identifying the home stations (i.e., a passenger's preferred station near their residence) of older passengers is developed to measure the aggregate demand at the bus stop scale. On this basis, a measurement that integrates the Gaussian two-step floating catchment area (2SFCA) and the adjusted 2SFCA methods (referred to as the adjusted Gaussian 2SFCA method) is proposed to measure accessibility to health care services for older people. The results show that: (1) almost all home stations experience inflated demand, especially those located in the suburbs; (2) despite abundant health care resources, home stations in urban districts are rarely identified as high accessibility stations, due to high demand densities among the older population; and (3) more attention should be paid to two types of home stations – those with a medical institution and those with bed shortages, respectively. The first type is predominantly distributed in the periphery of the city, in the suburbs where the travel time required to access the nearest health care service by bus is longer. The second type is mostly located in the outskirts of urban districts and in the central area of one suburb. These findings could help policy makers to implement more appropriate measures to design and reallocate health care resources.  相似文献   

4.
Urban public health is one of the most critical yet neglected aspects of urban planning in developing countries such as India. Inequity in access to government healthcare facilities affects the overall urban population and can substantially negatively impact the vulnerable population, who mostly rely on government healthcare services. In this paper, the accessibility measure for healthcare services by public transport is developed using travel time and the number of transit stops (accounting for transit connectivity) for Greater Mumbai. We also identified socially vulnerable wards (administrative units) using a Social Vulnerability Index (SVI), developed based on 16 indicators using Principal Component Analysis (PCA). Developed regression models showed that the proposed accessibility measure explains the coverage and usage of healthcare services better than the traditional accessibility measure, which is based on only aggregate level travel time impedances. South Mumbai has relatively better accessibility for public hospitals and dispensaries, whereas, lower level of accessibility is observed in the eastern part for public healthcare services. Assessment for the spatial inequity based on the Gini index, bivariate Moran's I, and mean access value reveals a higher degree of spatial inequity for accessing government hospitals for the slum population. The study developed a decision framework to suggest effective policy measures, which can be prioritised based on SVI to reduce the disparity in the spatial distribution of accessibility to government healthcare systems for vulnerable groups. Our findings can aid transportation and urban planners, health researchers, and policymakers to improve accessibility in under-served areas and give special attention to the needs of the vulnerable population.  相似文献   

5.
Equity in public transit ridership has attracted the attention of planning authorities as a mechanism to tackle social exclusion. The association of accessibility indexing with different income groups is fundamental to analyses of socio-spatial inequalities and identifying gaps in public transit services. However, few studies have addressed accessibility inequalities in medium-sized cities of the global South. This paper aims to identify spatial gaps in public transit service in seven medium-sized Brazilian cities by analyzing the relative accessibility of public transit and private automobiles for travel to central business districts (CBDs), which are primary employment and service centers. Demographic and socioeconomic data on the seven cities were extracted from the country's 2010 population census. To measure accessibility to CBDs, a Google Maps application programming interface was used to produce realistic estimates of travel times for public transit and private automobiles over different time periods. This method is more accurate than traditional accessibility calculation methods and provides real-time information on traffic conditions, such as speed limits, traffic jams, and waiting times. The study found significant intra-regional differences in accessibility to CBDs by public transit and private automobiles, providing a scientific basis to optimize the socio-spatial distribution of public transit services in seven cities in five different regions of Brazil.  相似文献   

6.
As accessibility becomes an increasingly relevant concept in the analysis of sustainable transport and urban development, the accuracy of accessibility measures becomes increasingly vital. While more complex measures are gradually gaining popularity with increasing data and computational resources, policy makers and planners are still prone to opt for less complex methods that are easy to use and interpret. The cumulative opportunities measure is the most widely applied accessibility measure in planning practice, but it is also among the least accurate due to its lack of consideration of the impact of competition for those opportunities. This study seeks to highlight the impact of addressing competition for different urban services in the cumulative opportunities measure. A competition component is added to the measure, which is applied to a case study of three types of urban services in the Perth metropolitan area; jobs, primary/secondary education and shopping. The results show that considering competition changes the spatial patterns of accessibility and its equity. Since this approach reveals demand-supply imbalances, it can more accurately determine spatial inequalities in accessibility, and hence increases the utility of the cumulative opportunities measure. We also find that the three services had varying levels and spatial patterns of accessibility and spatial equity, thus relying on any single one of them for assessing spatial structural performance can be misleading.  相似文献   

7.
TPL的物流服务水平与物流成本决策   总被引:1,自引:0,他引:1  
物流服务水平与物流成本之间存在效益悖反,对于第三方物流,进行物流服务水平与物流成本的权衡与决策是一项重要的战略性工作。借助经济学中的弹性概念进行TPL服务-成本能力分析,用以表明不同环境下物流成本对于物流服务水平变动的敏感程度,结合竞争环境和竞争对手水平、顾客需求等相关影响因素,实现对物流服务水平与物流成本的综合决策。  相似文献   

8.
The selection of airport is an important consideration for low-cost carriers (LCCs) to remain cost competitive. The objective of this study is to identify and rank the airport selection criteria of LCCs. Based on reviewing the existing literature, five main factors comprising 16 sub-factors were developed. The factors were first validated by three industry experts from the aviation industry. Thereafter, a survey questionnaire requiring a comparison of the factors was administered on 28 executives who were involved in the strategy planning and formulation of LCCs based in China or Korea. The collected data were analysed using fuzzy analytical hierarchy process (FAHP). In descending order of their importance, the main factors influencing LCCs' selection of airport are (1) airport charges, (2) airport performance, (3) airport growth opportunities, (4) catchment area and (5) airport infrastructure. The top three sub-factors are airport costs, demand for LCC services and passenger throughput. The research contributes to academic research by providing a holistic assessment of the key considerations influencing LCCs' selection of airport. In addition, it implicates policy formulation of LCCs by providing a framework for assessment of airports that are suitable for LCCs’ operations.  相似文献   

9.
The aim of the work presented here is to develop a mathematical model that can assist decision-makers in selecting the optimal network of subsidised routes in air transportation. Sweden is used as a case study. The results show that even if most of the Swedish population already has a good accessibility, the model can suggest new routes that can further improve accessibility without increasing the subsidisation cost. The closure of an airport reduces the available commercial routes, which would impair the accessibility to a given destination; a subsidised route would hence be required as a replacement. The ability of the model to consider several accessibility criteria makes it useful for managers at transportation authorities when making airport location decisions.  相似文献   

10.
In rapidly-growing metropolitan regions, it is crucial that transportation-related policies and infrastructure are designed to ensure that everyone can participate equitably in economic, social, and civil opportunities. Ridehailing services are touted to improve mobility options, but there is scant research that incorporates this mode within an accessibility framework. This paper employs a generalized cost measure in a multi-modal accessibility framework, namely Access Profile Analysis, to assess the role of ridehailing in providing job access to historically under-resourced parts of Toronto, Canada, referred to by the city as Neighborhood Improvement Areas (NIAs). Ridehailing is analyzed both as a mode of commute and as a feeder to the transit network (a first-mile solution). The results indicate that there are two main determinants of the extent to which ridehailing provides additional accessibility over transit: the transit level of service at the origin zone and the zone's proximity to employment opportunities. The ridehailing mode is shown to increase accessibility especially to closer destinations (jobs), with the highest improvement seen in the city's inner suburbs. On the other hand, integrating ridehailing with public transit does little to improve access to jobs. Compared to the rest of the city, NIAs experience a higher accessibility improvement from ridehailing alone, but not from its integration with transit. Nonetheless, job accessibility remains lower in NIAs than in other areas – even after the introduction of ridehailing.  相似文献   

11.
The achievement of good spatial accessibility and equity in the distribution of urban services is one of the supreme goals for urban planners. With Scottish Government backing, the City of Edinburgh Council (CEC) has started to construct a tram network to cater for the future needs of Scotland’s capital city by providing an integrated transport solution using trams and buses. Spatial Network Analysis of Public Transport Accessibility (SNAPTA) which is a GIS-based accessibility model has been developed to measure the accessibility by public transport to different urban services and activities. The model responds to several limitations in other existing accessibility models in planning practice. It offers an alternative and practical tool to help planners and decision makers in examining the strengths and weaknesses of land use – transport integration. SNAPTA has been applied to a pilot study in Edinburgh city to identify the contribution of the infrastructure improvements of the tram system and Edinburgh South Suburban Railway (ESSR) to improved accessibility by public transport to six types of activity opportunities. This paper outlines the concept and methodology of the SNAPTA model, and presents the findings related to this pilot study with a focus on changes in potential accessibility to jobs between four different public transport network scenarios. The accessibility values so obtained help to identify the gaps in the coverage of the public transport network and the efficiency in the spatial distribution of urban services and activities. The findings focus on whether the planned transport infrastructures for Edinburgh will lead to better accessibility and reduced inequity (in terms of accessibility) across the city.  相似文献   

12.
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   

13.
Domestic express coach services in Germany have long been heavily restricted by regulation, although offerings comparable to countries like, for example, Great Britain or Sweden bear substantial opportunities for competition, the environment, and mobility. In this paper, we motivate market entry in the German express coach market for local public and integrated transport companies by high profitability rates in other countries and the availability of bus facilities and skills. This is followed by the evaluation of supply and demand. Supply is represented by an analysis of external and internal costs showing that express coaches have significant cost advantages that are intensified by the possible internalization of external costs. Demand is represented by a survey of customers that is evaluated with a conjoint analysis. Our results suggest a market share for express coach services in Germany of at least 5.3%.  相似文献   

14.
We compare analytically and numerically the optimised performance of different urban public transport modes for three objectives: total cost minimisation, profit maximisation, and welfare maximisation. We find that under optimal operation, buses provide lower waiting time and operator costs, therefore the only possible advantage for rail is providing a lower in-vehicle time cost if trains are faster. Using Australian data, we found that bus rapid transit provides a lower total cost, higher profit and welfare, up to their capacity. Introducing passengers dislike of crowding and train-specific attraction elements might make Heavy Rail the most cost effective mode for high levels of demand.  相似文献   

15.
Urban population growth and economic development have led to the creation of new communities, jobs and services at places where the existing road network might not cover or efficiently handle traffic. This generates isolated pockets of areas which are difficult to reach through the transport system. To address this accessibility problem, we have developed a novel approach to systematically examine the current urban land use and road network conditions as well as to identify poorly connected regions, using GPS data collected from taxis. This method is composed of four major steps. First, city-wide passenger travel demand patterns and travel times are modeled based on GPS trajectories. Upon this model, high density residential regions are then identified, and measures to assess accessibility of each of these places are developed. Next, the regions with the lowest level of accessibility among all the residential areas are detected, and finally the detected regions are further examined and specific transport situations are analyzed.By applying the proposed method to the Chinese city of Harbin, we have identified 20 regions that have the lowest level of accessibility by car among all the identified residential areas. A serious reachability problem to petrol stations has also been discovered, in which drivers from 92.6% of the residential areas have to travel longer than 30 min to refill their cars. Furthermore, the comparison against a baseline model reveals the capacity of the derived measures in accounting for the actual travel routes under divergent traffic conditions. The experimental results demonstrate the potential and effectiveness of the proposed method in detecting car-based accessibility problems, contributing towards the development of urban road networks into a system that has better reachability and more reduced inequity.  相似文献   

16.
The Metrocable in Medellín, Colombia, is an innovative system to improve access to deprived areas located in hilly zones. The idea to use cable cars as feeders to the metro was integrated into an ambitious urban project that, to date, has improved accessibility dramatically for some low-income residents. Using data before and after the project’s implementation, we evaluate the impact on social equity for the population in the zone of influence, considering changes in accessibility to employment and in housing-related costs. The access provided by the project to the main high-employment centres has doubled the number of opportunities that can be reached by the “target population,” even though travel-time savings and costs have seen only small changes. In fact, prior access to the CBD was poor and expensive, but time and costs were reduced with the Metrocable, although this reduction was not equal for all locations in the metropolitan area. In general, we argue that the main benefits, in terms of accessibility that differentiates the areas analysed from those used for comparison, are related to a localised ease of access to specific centres of activity according to the centralised development of the city’s job market along the mass transit lines. In terms of housing costs, we developed a set of difference-in-difference models that considered rent, transport, and public utilities costs; however, none of them have allowed us to conclude that there was a statistically valid relationship between the Metrocable and the changes in costs between the two analysed populations.  相似文献   

17.
Transformative mobility services present both considerable opportunities and challenges for urban mobility systems. Increasing attention is being paid to ridehailing platforms and connections between demand and continuous innovation in service features; one of these features is dynamic ride-pooling. To disentangle how ridehailing impacts existing transportation networks and its ability to support economic vitality and community livability it is essential to consider the distribution of demand across diverse communities. In this paper we expand the literature on ridehailing demand by exploring community variation and spatial dependence in ridehailing use. Specifically, we investigate the diffusion and role of solo requests versus ride-pooling to shed light on how different mobility services, with different environmental and accessibility implications, are used by diverse communities. This paper employs a Social Disadvantage Index, Transit Access Analysis, and a Spatial Durbin Model to investigate the influence of both local and spatial spillover effects on the demand for shared and solo ridehailing. The analysis of 127 million ridehailing rides, of which 15% are pooled, confirms the presence of spatial effects. Results indicate that density and vibrancy variables have analogue effects, both direct and indirect, on demand for solo vs pooled rides. Instead, our analysis reveals significant contrasting effects for socio-economic disadvantage, which is positively correlated with ride-pooling and negatively with solo rides. Additionally, we find that higher rail transit access is associated with higher demand for both solo and pooled ridehailing along with substantial spatial spillovers. We discuss implications for policy, operations and research related to the novel insight on how pooled ridesourcing relate to geography, living conditions, and transit interactions.  相似文献   

18.
Approximately one-fifth of Perth’s population is aged 60 or older. Projections suggest that this proportion will continue to increase as a result of the large number of children born after the World War II (1946–1964). Access to and accessibility around train stations for the aging population is and will become a more important issue as the elderly population continues to grow. The aim of the paper is to develop and apply a new measure of accessibility to train stations at a fine spatial scale, justified by the special circumstance of the elderly using a case study in Perth, Western Australia. Intercept surveys are used to collect data on factors affecting train station accessibility for patrons aged 60 years or older, at seven highly dispersed train stations. Overall accessibility is measured separately using a composite index based on three travel modes (walk-and-ride, park-and-ride and bus-and-ride). The results illustrate that key variables, such as distance from an origin to a station, walking or driving route directness, land-use diversity, service and facility quality, bus connection to train stations, all affect the accessibility to train stations for the elderly. This implies that improvements to these factors will improve accessibility for this population group.  相似文献   

19.
Spatial labour markets are subjected to the forces of regional economic activity and competing network effects. Commuting is, therefore, an important equilibrating vehicle in a City Network constellation. Cities act as attractors of commuters, as most economic activity occurs in cities, thus providing a high share of attractive workplaces. Cities that are centrally connected in a network may act as both centripetal and centrifugal forces in the whole system. The present paper focuses on what is named the City Network (CN) approach. A central idea is the accessibility concept, which is interpreted here as the potential of opportunity for interaction, which has a positive impact on economic growth. In our paper, the accessibility concept and the CN concept are linked together by positioning accessibility in the CN system. Since accessibility measures give geographical insights into the distribution of economic activities and the related (dis)equilibrium of regional development patterns, the connection with the labour market is evident, and, therefore, a second focus of our analysis.In an applied setting, our paper aims to investigate spatial accessibility patterns in the main CN in Germany. The 17 districts which belong to the country’s CN were chosen from the 439 German labour market districts on the basis of three criteria: (a) their connection to the high speed railway network; (b) the most accessible districts according to previous results (2002); (c) relevant districts for the German economy. Our applied modelling research concerns home-to-work commuters travelling between the selected districts belonging to the German CN, for both 2003 and 2007. Here, a comparative analysis of the ranking of the most accessible districts - also for different intra-zonal travel times - is carried out in order to map out the changes in accessibility between 2003 and 2007, especially in the light of new high speed connections and commuting flow dynamics.  相似文献   

20.
The Indian aviation industry has a vast potential to grow to cater to its population and commerce through developing air transport services to the regional airports. This paper examines the possible determinants of domestic air traffic demand in Indian regional airports serving below three million passengers per annum. Using multiple regression analysis, we find that distance to the nearest airport and accessibility of the airport significantly affect traffic volumes in regional airports. This study also highlights the specificities of Indian regional airports.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号