Greenhouse gas emissions from flying can offset the gain from reduced driving in dense urban areas

Numerous studies have illustrated how denser urban forms lead to smaller greenhouse gas (GHG) emissions from passenger transport. Many of these studies have excluded aviation since the association between urban structure and air travel is not as intuitive as it is the case of ground travel. However, several recent studies have concluded that air travel is a significant contributor to the GHGs from passenger transport. Furthermore, even air travel habits depend heavily on lifestyles and socio-economic factors that are related to the urban form. Here we analyse the interactions between urban structure and different transportation modes and their GHG impacts in Finland. The study utilises the data from the Finnish Transportation Agency’s passenger traffic survey from May 2010 to May 2011, which includes over 12 000 people and over 35 000 trips. The survey is based on one-day travel diaries and also includes additional data on long-distance trips from a longer period. Methodologically, the study takes a traveller’s perspective to assess the GHG emissions from passenger transport. We found that (1) air travel breaks the pattern where GHG emissions decrease with increasing density of urban structures, and (2) in the metropolitan region there is a clear trade-off between car-ownership and air travel in the middle income class. The main policy implication of our study is that air travel must be included in GHG assessments and mitigation strategies targeting travel behaviour. In dense urban regions, the emissions of air travel have the potential to offset the gain from reduced private driving.     

Greenhouse gas impacts of different modality style classes using latent class travel behavior model

This study analyzed the interconnections between urban structure and socioeconomic, demographic and lifestyle variables and direct ground transport greenhouse gas (GHG) emissions in the Helsinki metropolitan region in Finland by using a latent class choice model (LCCM). The aim of the study was to identify and improve our understanding of the latent modality styles which guide people's everyday travel choices, and the resulting GHG implications. The GHG implications for different modality style groups are particularly interesting, since such analysis has not been included in previous studies. This study used the transport survey of the Helsinki Region Transport (HSL) from 2012, including over 17,000 trips, and consisted of two parts: first, the population was divided into classes based on latent class analysis, and secondly, the mode choices and GHG emissions were modelled for each class. Seven modality style groups were defined with strongly varying GHG impacts and travel profiles. According to the class specific choice modelling the probabilities of selecting different modes also varied significantly. The study offers new information for designing effective mitigation policies for different types of modality style groups. For example, car-oriented groups would benefit from more fuel-efficient vehicles and vehicles with alternative power sources, whereas the multimodal traveler could be more receptive to policies promoting cycling and public transport. Overall, the study depicts the potential of the latent class method to study the emissions caused by heterogeneous populations and to search for efficient GHG mitigation possibilities.     

Spatial-modal scenarios of greenhouse gas emissions from commuting in Hong Kong

Transportation is a major source of greenhouse gas emissions in cities. Multiple strategies including green technologies, transport management, urban planning and behavior changes are required to mitigate transport emissions. This paper aims to introduce an analytical framework to investigate the impacts of different spatial-modal strategies on reducing commuting emissions. Based on the optimization approach of excess commuting, the proposed framework incorporates the minimum, maximum and random (unpredictable) travel outcomes to inform planning of an urban form embedded with fewer emissions. This analytical framework is applied to Hong Kong to estimate the emissions ranges (the minimum and maximum amounts) under 42 spatial-modal scenarios - a combination of six spatial strategies (status quo, monocentric, highly polycentric, moderately polycentric, dual-centric and tri-centric) and seven modal strategies (status quo, pro-rail (high), pro-rail (moderate), pro-bus (high), pro-bus (moderate), pro-car (high) and pro-car (moderate)). The findings illustrate the emissions impacts if Hong Kong is further developed following a job concentration or decentralization principle. It also indicates that if Hong Kong is reconstructed to be a city with multiple CBDs, a dual-centric strategy is desirable because both minimum and maximum commuting are shorter than that of a tri-centric strategy. Moreover, the modal strategy to actively promote rail usage shows more impacts on emissions reduction and car usage should be maintained at the current level. If commuter's travl is less predictable, the high rail usage under a dual-centric city form is a more sustainable spatial-modal strategy. The proposed analytical framework of city's commuting emissions affected by structural and modal changes is transferrable to other places and could offer planners different benchmarks of travel pattern to substantiate their sustainable city planning vision.     

Interplay between ethanol and electric vehicles as low carbon mobility options for passengers in the municipality of São Paulo

The Brazilian cities as well as many of the large urban centers in the world continue to expand, increasing the demand for mobility and transport, while, at the same time, the same cities are investing in greenhouse gas (GHG) mitigation to avoid climate change. Brazil's urbanization rate increased from 26% in 1940 to almost 70% in 1980. During this period, the Brazilian population tripled and the urban population multiplied by seven. In 2010, the transport sector in São Paulo accounted for 71% of the total emissions released by the energy sector. Ethanol has been considered a fuel with less greenhouse gas emissions, when compared with fossil fuels. However, ethanol production would have to double to meet the expected demand. Electric vehicles (EVs) market is expanding around the world, and is also an option to reduce the transport emissions, if powered by clean electricity. To assess whether the adoption of EVs might bring more benefits than the current ethanol, we develop prospective scenarios supported by the Long-range Energy Alternatives Planning (LEAP) simulation tool, taking a bottom-up tank-to-wheel approach to consider the CO₂ emissions of car in São Paulo. The scenario considering a substitution of 25% of gasoline-powered cars by EV in 2030 showed a reduction in energy consumption and CO₂ emissions, around 15% and 26% respectively in that year in comparison with 2015. We discuss the interplay between ethanol and EV, also considering emission coefficients from life cycle analysis conducted in Brazil, and concluded EV will have higher positive impact on climate change mitigation than ethanol.     

The greenhouse gas mitigation potential of university commuting: A case study of the University of León (Spain)

This work analyzes the main drivers and critical aspects of mobility at the University of León (ULE) in Spain and its potential for mitigation of greenhouse gases (GHG). Through the implementation of a life cycle analysis (LCA) methodology (door-to-door and well-to-wheel approach), we examine the existing relationships between modal distribution, distances, travel times, urban structure, and direct and indirect carbon footprint and monetary costs of ULE users' commuting to its premises. Necessary primary information was collected by means of an online survey conducted on all ULE bodies and actors. Even though most distances traveled to the University are of <6 km (94.3% of the commutes), the use of the private car is second in importance (34%) after traveling by foot (41.5%), as well as the main hotspot in environmental terms (95% of GHG emissions). The results show how university policies focused on improving mobility habits (greater use of bus, bicycle and walking) can considerably reduce GHG emissions within a distance range of 0–6 km. For instance, the replacement of cars with bicycles (50% in <4 km distances) would reduce CO₂-eq emissions by 17.5% and increase monetary savings by 14.8%. However, 5.8% of the remaining travels (> 6 km) accumulate 49.4% of the emissions. Beyond that distance, behavior-oriented policies prove to be insufficient, and actions and measures at other levels encouraging technological change (use of electric cars and bicycles, etc.) and the improvement of infrastructures are also required. This article discusses the role of universities in promoting improvement of sustainable mobility within its premises.     

Using GIS tools to estimate CO2 emissions related to the accessibility of large retail stores in the Oulu region, Finland

Everyday traffic accounts for a significant share of overall greenhouse gas emissions, in particular carbon dioxide (CO₂). While several solutions have been proposed for decreasing the emissions, a new kind of land use planning is required in order to achieve long-term effects. This study focuses on the effect of large retail store locations in the urban structure on overall CO₂ emissions, by using the Oulu region, Finland, as a case study. The aim was to utilize GIS tools to assess store locations in terms of CO₂ emissions from private cars used for consumer traffic. In this case, not only are the locations of the existing and planned retail units investigated with respect to population distribution and car ownership, but the analysis is also carried out by regarding any location within the study area as a hypothetical site for a large retail unit. According to the applied method, CO₂ values are lowest near the centre of the studied region, the region with the highest population density, although the city centre itself did not turn out to be the most optimal location for a retail store in terms of CO₂ emissions. Nevertheless, by generally reducing trip length, a compact urban structure is an important way of achieving long-term cuts in CO₂ emissions.     

Inside the black box: EU policy officers' perspectives on transport and climate change mitigation

Transport is a significant and growing contributor to climate change. To stay within ‘safe’ global warming guardrails requires substantial cuts in greenhouse gas emissions. This represents a global political consensus, but there is evidence that current legislation in the transport sector is not significant enough to achieve medium- and longer-term reduction goals. In focusing on the European Union, this paper investigates the perspectives of twelve policy officers in three Directorates-General (MOVE, CLIMA, ENV) of the European Commission with regard to their understanding of mitigation goals and timelines, responsibilities for policy development and implementation, and perceived efficiencies of these policies to achieve climate objectives in the transport sector. Results indicate diverging and common views on climate policy goals and political responsibilities, as well as barriers to policy-making, including lack of political leadership on climate change mitigation, resistance from member states, the favoring of economic growth over cuts in greenhouse gas emissions, pressure from industry and lobby groups, preferential treatment of aero- and automobility over more sustainable transport modes, policy implementation delays, insufficient forecasting and monitoring tools, and an overreliance on technologies to contribute to emission reductions. In offering a view inside the ‘black box’ of transport policy-making, the paper reveals fundamental institutional (structural) and individual (agency-based) barriers that will have to be overcome if significant emission cuts in the transport sector are to be achieved.     

Excess kindergarten travel in Changchun,Northeast China: A measure of residence-kindergarten spatial mismatch

Home-kindergarten travel is an important urban travel activity. This paper firstly discussed the relationship between excess kindergarten travel and residence-kindergarten spatial mismatch. And then questionnaires and GIS are used to provide some baseline analyses of their distribution pattern both statistically and spatially in Changchun. Thirdly, we provide an exploratory analysis of the causes of excess kindergarten travel and spatial mismatch. Results indicate that a) kindergartens in Changchun are highly accessible if children attend their nearest kindergartens, b) however, there is numerous excess travel and high degree of spatial mismatch, nearly 87.1% of the kindergarteners travel excessively, c) the excess travel distances in inner city are much shorter than other areas, and the corresponding spatial mismatch degree is lower. Two critical factors influencing excess kindergarten travel and residence-kindergarten spatial mismatch are summarized. Firstly, the actual causes are a) parents' personal preferences and kindergarten choice tendencies, b) Danwei owned kindergartens generally with higher quality, tendentious enrollment policies, charge threshold, and c) the widespread use of private cars. Secondly, the root causes are limited public expenditure on kindergarten education and its unbalanced allocation, as well as Chinese traditional concept and prevailing way of parenting.     

Examining the spatial-temporal relationship between urban built environment and taxi ridership: Results of a semi-parametric GWPR model

With the advance of intelligent transportation systems (ITSs) and data acquisition systems (DASs), it becomes possible in recent to explore the determinants of urban taxi ridership using multi-source heterogeneous data. This paper aims to use floating car data, points-of-interests (POIs) data and housing-price data to assess the influence of the built environment on taxi ridership. Within a scale of 0.5 km grid, critical indicators related to the economic aspect, intermodal connection, and land use factors were obtained using the multi-source data in Shanghai. To capture the spatial and temporal heterogeneity, Semi-parametric Geographically Weighted Poisson Regression (SGWPR) models are built over different time dimensions. It is found that SGWPR models result in higher goodness-of-fit than the generalized linear models. More importantly, the results show the impacts of built environment factors on taxi demand are highly heterogeneous, positive or negative in different city areas, reflected in the significant temporal variations of the effects. Overall, these findings suggest that the built environment factors have significant impacts on urban taxi demand, and the spatial context should not be ignored. Findings in this paper are expected to help better understand the relationship between urban taxi demand and built environment factors, improving the service level of the urban taxi system, and offering valuable insights into future urban and transportation planning.     

Municipal solid waste management and greenhouse gas emissions at international airports: A case study of Astana International Airport

The steady expansion of the city of Astana and the increase of airport capacity is leading to an increase in municipal solid waste generation. The purpose of this study was to perform compositional analysis of the municipal solid waste produced at the Astana International Airport and evaluate different waste management scenarios in terms of greenhouse gas emissions. Recyclable and combustible fractions were found to be the major fractions (over 50%) of the total municipal solid waste generated in the Astana International Airport. Four base greenhouse gas emissions scenarios were proposed in this study, namely scenario-1 describing the current municipal solid waste management case, scenario-2 with integration of 29% recycling and 71% of municipal solid waste landfilling, scenario-3 for 100% of airport municipal solid waste being incinerated and scenario-4 for recycling 29% and the remaining waste being processed for energy recovery purposes. The proposed scenario 2 demonstrated significantly reduced net greenhouse gas emissions (t CO₂ eq/year) over the existing scenario 1, while scenarios 3 and 4 showed negative net greenhouse gas emissions. The experimental data provided and the scenarios discussed in this work are useful tools for decision makers for environmental waste management at airports.     

Commute travel and its effect on housing tenure choice of males and females living in the urban and rural areas of Bangalore city in India

This study attempts to identify various factors influencing individual’s choice of housing tenure with emphasis on the effect of commute trips on that choice. It also focuses on the sensitivity to various factors affecting the housing tenure choice between males and females of urban and rural areas. The study is based on both exploratory analysis and estimation of statistical models using a Household Travel Survey data collected for Bangalore Metropolitan Region in year 2010. The results indicate the role of both the land use attributes and commute travel characteristics on tenure choice and the behavioural difference between males and females. The sensitivity to various attributes is also observed to be varying between the individuals living in the urban and rural areas of the city. The finding that private mode use for commuting governs the housing tenure choice of individuals suggests that promotion of urban-transport policies such as Transit Oriented Development may be an effective strategy to curb the issues related to energy consumption and emission.     

Assessing equity in transport accessibility to work and study: The Bogotá region

This research was aimed at exploring levels of equity in accessibility to employment and education in the city-region of Bogotá, Colombia's capital city. Building on consolidated methodologies for the assessment of potential accessibility, we estimate accessibility indicators at the zone level, evaluate how potential accessibility varies among income groups, and present evidence related to transport mode, in order to analyze social and spatial inequalities produced by the distribution of accessibility to employment and education activities. The research incorporates a method to evaluate how accessibility varies among zones according to average income and mode of transport in order to produce evidence-based arguments that can inform transport policy in the city-region of Bogotá, and other similar contexts in the Global South. Our results show strong distributional effects of the socio-spatial and economic structure of the city-region, its transport infrastructure and services, and the effect of current transport and land-use policies for citizens of different income groups. The tools and empirical evidence in this research seek to contribute to informed policy development in Latin America and other developing contexts, and feeding current debates on the role of accessibility in addressing social and spatial inequalities stemming from urban mobility.     

Port activities and the spatial structure of cities: the case of Freetown, Sierra Leone

Port activities often give rise to distinctive regions within their town or city and it might be expected that they would have on effect on the spatial differentiation and spatial structure of urban areas. However, urban spatial theory appears to ignore this possibility, urban structure models having little or nothing to say about the role of port activities in shaping the spatial structure of towns and cities. Given this, the paper investigates the possibility of port activities having influenced the spatial structure of Freetown, Sierra Leone. It discusses the historical development of the port and city as a framework for consideration of the role of port activities in shaping the growing urban area. Attention is focused particularly on those areas where the influence is clearest, i.e. the central area with its concentration of business, commercial and administrative activities, and on the location of modern industrial areas in the emerging metropolitan area. Other factors that have shaped the urban area are discussed also. It is argued that, whilst port activities have been important historically, other influences have become more significant as the basis of the economy has broadened, the structure of society has become more complex and the city has assumed additional functions. The findings are tested by a brief and preliminary examination of other port-cities in tropical Africa, establishing that spatial associations between port activities and the central business area and between them and industrial areas are common.     

Analysing transport corridor policies: An integrative approach to spatial and social disparities in India

Although strategies to create transport corridor are prevalent in the global South, there is a lack of empirical research to evaluate these initiatives, in particular whether they have realised their general goal of reducing regional disparities. The current paper describes a multi-method approach involving spatial and non-spatial analysis to investigate spatial disparity along a proposed corridor and examine its integration within the existing settlement structure. The analytical framework is tested on India’s Delhi-Mumbai Industrial Corridor. A rationale is developed to enable a critical view of corridor policies as strategies for development in the global South.One important finding regarding policies on transport corridors is the risk that future growth will remain concentrated in districts directly linked to a proposed corridor, leaving peripheral areas marginalised. An integrative analysis of current spatial and social disparities in India shows growth to be high in areas with good accessibility between urban and rural areas. Specifically, growth in rural areas is fostered by the availability of good road network, and polytechnic and vocational institutions, whereas in urban areas, growth is positively associated with the provision of secondary schools. In order to prevent or even reduce disparities, this research recommends that spatial strategies be developed with mechanisms to enable their implementation by lower tiers of governments, that spatial plans and infrastructure outlays be reformed to improve accessibility between proposed corridors and peripheral areas, and that accessibility indicators be included in the design and implementation of transport development policies.     

Spatial disparity of income-weighted accessibility in Brazilian Cities: Application of a Google Maps API

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.     

‘60-20 emission’—The unequal distribution of greenhouse gas emissions from personal,non-business travel in the UK

Relatively little is known about the composition of greenhouse gas emissions from personal, non-business travel at the disaggregate levels. This paper aims to give insights into the distribution of emissions amongst the UK population. When including non-carbon climate effects air travel dominates overall greenhouse gas emissions. There is a huge range in emissions, with the highest 20% of emitters producing 61% of emissions. This ‘60-20 emission’ rule is surprisingly similar across units and scale of the analysis. Disaggregated data tell a different story than aggregated data. While income, working status, age and car ownership are significantly related to overall emissions, factors related to accessibility, household location and gender are not.     

Planning for low carbon mobility: Impacts of transport interventions and location on carbon-based accessibility

Accessibility has been conceptualized and applied in different ways, depending on the underlying political objectives. In the context of climate change and ambitious emission reduction targets, environmental concerns have risen high on the political agenda. Existing methods for assessing transport-related environmental impacts typically depend on realized or modeled travel behavior. Many of them do not entail a spatial dimension, ignore the importance of the land use component, lack scenario building capabilities or have limited communication value. Consequently, accessibility analysis and planning could make a valuable contribution towards a low carbon transition, but needs to attune to the specific objective of reducing transport-related greenhouse gas emissions. This paper introduces a novel conceptualization of location-based accessibility, where CO₂ emissions are used as a travel cost in place of time or monetary costs. By identifying and assessing options for interventions in the land use and transport system, carbon-based accessibility instruments might serve a number of potential decision-making purposes related to low carbon mobility planning. Carbon-based accessibility of a business park in the Munich region is analyzed in multiple scenarios to demonstrate the application potential of the method. The experiential application focuses on the effects of changes in vehicle efficiency and occupancy rates of both car and transit, but also compares the resulting carbon-based accessibility levels to alternative sites with the transport system unchanged. Applying carbon-based accessibility instruments to real-world planning issues could enhance strategic decision-making processes in the context of climate change mitigation.     

The impact of metropolitan,county, and local land use on driving emissions in US metropolitan areas: Mediator effects of vehicle travel characteristics

Many municipalities in the U.S. pursue compact development to reduce greenhouse gas (GHG) emissions from driving. Despite the efforts, however, recent studies suggest that some land use strategies such as densification and mixed-use development may result in slower vehicle movements, and consequently generate more driving emissions. Since vehicle miles of travel (VMT) is only a proxy and not an exact measure of emissions, reduction in VMT may not lead to a proportional reduction in transportation GHG emissions. Aside from local land use efforts, regional factors also influence vehicle travel and associated emissions.This study investigates the relationship between land use, vehicle travel, and driving emissions in the selected U.S. metropolitan areas at multiple geographic levels. The study employed structural equation modeling (SEM) techniques to examine how land use influences vehicle travel characteristics and associated emissions. The main data sources for the analyses include the 2009 National Household Travel Survey (NHTS) add-on samples and the Smart Location Database (SLD) from the U.S. Environmental Protection Agency (EPA). The study results show that VMT reduction and the associated environmental benefit do not show a one-on-one relationship due to the emissions penalty of lowered vehicle operating speed. Vehicle travel and associated emissions are not only influenced by local urban form factors but also affected by the greater geographical context.     

Aviation’s inclusion in international climate policy regimes: Implications for the Caribbean tourism industry

Nations with tourism dependant economies are becoming increasingly concerned about the inclusion of aviation in greenhouse gas mitigation policy for international bunker fuels and more recently adaptation policy proposals. The central concern is that such policies will increase the cost of traveling by air, therefore reducing visitor arrivals to long-haul, tourism-dependent destinations, often small island developing states. This study used a tourism arrivals model to examine the implications of currently proposed climate policies for the world’s most tourism dependant region – the Caribbean. Results indicate that under current proposals for both mitigation and adaptation focused climate policy, reductions in tourist arrivals from the major markets of Europe and North America would be negligible versus business as usual growth projections Only under the most stringent mitigation policy scenario. Which may portend a post-2020 policy regime, is a significant decrease in tourist arrivals predicted. Of the climate policies assessed, the adaptation policy had the potential to provide greater economic benefits to the Caribbean region.     

The impact of urban features in cycling potential – A tale of Portuguese cities

While the bicycle is commonly understood as a suitable alternative to fulfil most of urban mobility needs, adoption rates of this transport mode vary considerably among urban areas. Those at early stages of adoption, identified as starter cycling cities, face numerous challenges, reducing the effectiveness of policies and strategies. Much research has been dedicated at identifying social and physical environment conditions favouring the use of the bicycle. Assuming cycling potential results of a good combination of physical and socio-demographic factors, we set out to identify dominant contexts generating high levels of cycling potential. The previously developed Gross Potential for Cycling is applied to 21 Portuguese municipalities of different spatial contexts. By looking at the particularities of different typologies of urban territories, a set of k-means clustering analyses investigates which combination of factors contribute to the establishment of a high cycling potential.The results indicate that, in the set of case studies, high accessibility to schools and urban centralities are common in high cycling potential areas, regardless of spatial context. Three clusters were identified from the combination of the age profile of residents and the connectivity features of the territory, defining the main typologies of high cycling potential areas. As different urban typologies pose distinct configurations on the performance of the different evaluated indicators, these outcomes are crucial to inform policy makers on where to prioritize investment for the establishment of a new cycling culture.