How to plan for regional accessibility?

In order to address some of the shortcomings of traditional urban transportation planning, it is argued that a shift is needed from planning for mobility to planning for accessibility. Accessibility is a well-known and studied concept within the scientific literature. Its use in practice however is limited. This paper explores the ways of using the concept of accessibility in planning practice, with a special focus on the phase of policy design. Using the Amsterdam Region as an example, it is illustrated how simple accessibility measures can help planners with the design of integrated transport and land-use policies that call for different solutions than the traditional approach.     

Perceived accessibility: What it is and why it differs from calculated accessibility measures based on spatial data

Accessibility is usually evaluated using indicators calculated from spatial data. However, perceived accessibility, defined as the perceived potential to participate in spatially dispersed opportunities, is often poorly reflected by these calculated measures. This paper sets out to explain the mechanisms that lead to these mismatches. A conceptual model is constructed to establish what factors shape perceived accessibility. A schematic framework shows that mismatches between a calculated indicator and perceptions can stem from inaccuracies in awareness as well as from inaccuracies in the measure if the measure fails to take account of the subjective evaluations of accessibility components. When evaluating the performance of land-use and transport system configurations, calculated measures based on spatial and transport data only serve as proxies for how accessibility is actually experienced. This paper argues that bringing perceived accessibility to the fore of accessibility-based planning, by acknowledging and evaluating potential mismatches with calculated accessibility indicators, will advance the evolution from mobility-based to accessibility-based planning.     

Measuring the accessibility and spatial equity of urban services under competition using the cumulative opportunities measure

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.     

Daily fluctuations in transit and job availability: A comparative assessment of time-sensitive accessibility measures

Accessibility to jobs by transit is increasingly incorporated into transportation and land-use planning objectives, as it is proven to be a relevant indicator for assessing land-use and transport performance. With a rise in time-sensitive accessibility measures, choosing the appropriate measure is increasingly challenging for engineers, planners and policy-makers. This research presents a comparative analysis of three accessibility measures, two of which are time-sensitive. Relative accessibility measures are generated for five time periods based on a) constant transit service and number of jobs (constant); b) variable transit service and constant number of jobs (static) and c) variable transit service and variable number of jobs available (dynamic). The measures are first assessed by incorporating them into a transit mode share model. Interestingly, findings show that all three measures behaved similarly in the three regression models. Furthermore, all accessibility measures are found to be highly correlated. The study suggests that the most commonly used accessibility measure (constant measure at 8 am) is representative of the relative accessibility (static or dynamic) over the course of the day and is thus appropriate and meaningful to be used by policy-makers, engineers and planners.     

Accessibility and the journey to work through the lens of equity

Inequality in transport provision is an area of growing concern among transport professionals, as it results in low-income individuals travelling at lower speeds while covering smaller distances. Accessibility, the ease of reaching destinations, may hold the key in correcting these inequalities through providing a means to evaluate land use and transport interventions. This article examines the relationship between accessibility and commute duration for low-income individuals compared to the higher-income, in three major Canadian metropolitan regions, Toronto, Montreal, and Vancouver using separate multilevel mixed effects statistical models for car and public transport commuters. Accessibility measures are generated for jobs and workers both at the origin (home) and the destination (place of work) to account for the impact of competing labor and firms. Our models show that the impacts of accessibility on commute duration are present and in many cases stronger for low-income individuals than for higher income groups. The results suggest that low-income individuals have more to gain (in terms of reduced commute time) from increased accessibility to low-income jobs at the origin and to workers at the destination. Similarly, they also have more to lose from increased accessibility to low-income workers at the origin and to low-income jobs at the destination, which are proxies for increased competition. Policies targeting improvements in accessibility to jobs, especially low-income ones, by car and public transport while managing the presence of competition can serve to bridge the inequality gap that exists in commuting behavior.     

Assessing transport related social exclusion using a capabilities approach to accessibility framework: A dynamic Bayesian network approach

Accessibility is considered to be a valuable concept that can be used to generate insights on issues related to social exclusion due to limited access to transport options. Recently, researchers have attempted to link accessibility with popular theories of social justice such as Amartya Sen's Capabilities Approach (CA). Such studies have set the theoretical foundations on the way accessibility can be expressed through the CA, however, attempts to operationalise this approach remain fragmented and predominantly qualitative in nature. In this study, a novel framework of expressing accessibility at the level of an individual is proposed, based on the basic elements of the CA. In particular, dynamic Bayesian networks are used to express the causal relationship between capabilities, functionings, personal and environmental characteristics. This is done by introducing informative Dirichlet prior distributions constructed using data from traditional mobility surveys, modelling the transition probabilities with data related to place based characteristics and defining an observation model from unlabelled mobility data and places of interest (POI). We demonstrate the usefulness of the proposed framework by assessing the equality levels and their link to transport related social exclusion of different population groups in London, using unlabelled, service provider generated mobility data.     

Twenty years of accessibility improvements. The case of the Spanish motorway building programme

This paper presents an exploratory spatial data analysis of accessibility impacts of a large-scale national motorway building programme. Accessibility is calculated for Spanish municipalities from 1980 to 2000 using two indicators: motorway network access and market potential accessibility. The average distance from municipalities to their nearest motorway has been reduced markedly over this period. Market potential accessibility maps show that there have been gains in all locations, but some of the highest gains occurred in some of the more peripheral regions. A review of the theoretical and empirical literature on the economic impacts of transport investments indicates important implications for regional development.     

Estimating the influence of crowding and travel time variability on accessibility to jobs in a large public transport network using smart card big data

Accessibility metrics are gaining momentum in public transportation planning and policy-making. However, critical user experience issues such as crowding discomfort and travel time unreliability are still not considered in those accessibility indicators. This paper aims to apply a methodology to build spatiotemporal crowding data and estimate travel time variability in a congested public transport network to improve accessibility calculations. It relies on using multiple big data sources available in most transit systems such as smart card and automatic vehicle location (AVL) data. São Paulo, Brazil, is used as a case study to show the impact of crowding and travel time variability on accessibility to jobs. Our results evidence a population-weighted average reduction of 56.8% in accessibility to jobs in a regular workday morning peak due to crowding discomfort, as well as reductions of 6.2% due to travel time unreliability and 59.2% when both are combined. The findings of this study can be of invaluable help to public transport planners and policymakers, as they show the importance of including both aspects in accessibility indicators for better decision making. Despite some limitations due to data quality and consistency throughout the study period, the proposed approach offers a new way to leverage big data in public transport to enhance policy decisions.     

Job accessibility through public transport and unemployment in Latin America: The case of Montevideo (Uruguay)

Accessibility to job opportunities is one of the factors that explains labor outcomes. For developing countries, public transport plays a key role in providing the population with access to employment opportunities. This paper aims to quantify accessibility by public transport to employment in Montevideo, Uruguay and to explore how accessibility to job opportunities via public transport relates to unemployment. To do so, we calculate a cumulative measure of accessibility to job opportunities for 1063 small zones—approximately 4–6 blocks each—within Montevideo. This measure yields accurate data on accessibility and can be assigned to individual households. Accessibility in Montevideo is unevenly distributed among social strata and is concentrated within the central (and wealthier) areas of the city. In addition, a multilevel logistic regression analysis indicates that greater accessibility to jobs via public transport is associated with a lower probability of being unemployed. This finding suggests that improving accessibility to job opportunities via public transit may enhance individual labor outcomes.     

Future accessibility impacts of transport policy scenarios: Equity and sensitivity to travel time thresholds for Bus Rapid Transit expansion in Rio de Janeiro

The accessibility impacts of transport projects ex-post implementation are generally evaluated using cumulative opportunity measures based on a single travel time threshold. Fewer studies have explored how accessibility appraisal of transport plans can be used to evaluate policy scenarios and their impacts for different social groups or examined whether the results of project appraisals are sensitive to the time threshold of choice. This paper analyzes how different scenarios of full and partial implementation of the TransBrasil BRT project in Rio de Janeiro (Brazil) will likely impact the number of jobs accessible to the population of different income levels. The analysis is conducted under various travel time thresholds of 30, 60, 90 and 120 min to test whether the results are sensitive to the boundary effect of the modifiable temporal unit problem (MTUP). Compared to a partial operation scenario, the full implementation of TransBrasil that extends this corridor into the city center would lead to higher accessibility gains due to network effects of connecting this BRT to other transport modes. Nonetheless, the size of the accessibility impacts of the proposed BRT as well as its distribution across income classes would significantly change depending on the time threshold chosen for the accessibility analysis. Considering cut-off times of 30 or 60 min, both scenarios of TransBrasil would lead to higher accessibility impacts in general and particularly for low-income groups, moving Rio towards a more equitable transportation system. However, under longer thresholds of 90 and 120 min, an evaluation of this project would find much smaller accessibility gains more evenly distributed by income levels. The paper highlights how time threshold choice in cumulative opportunity measures can have important but overlooked implications for policy evaluation and it calls for further research on the MTUP in future transport and mobility studies.     

Population change and accessibility by road and rail networks: GIS and statistical approach to Finland 1970-2007

This study analyzes the relation of accessibility by road and railway network to population change between the years 1970-2007 in Finland. Accessibility is evaluated at built-up area unit and municipal levels by potential accessibility analysis and by measuring accessibility to network. Analyses are done in decadal periods by using geographical information systems (GIS) and data about road and railway networks involving digitized speed limits and geometry for each period. Accessibility variables and population change are related by generalized additive models (GAMs). The results indicate that the Finnish population has concentrated to areas with high road-based potential accessibility, especially since the opening in the Finnish economy in the 1990s. The accessibility of railway network was found to have affected the population change in the 1970s, when local level traffic reduced in the entire country, and in 2000-2007, following remarkable investments in long-haul transport.     

Policy packages and state engagement: Comparing car-use reduction policy in two Norwegian cities

Policy packages are structures used to combine different policy measures and address multiple objectives. This paper links local-level policy packaging with national authorities’ environmental strategies. Applying a multilevel-governance perspective, it examines how state engagement influences the integration of car-use reduction strategies in local policy packages. Two policy packages are empirically compared, one from the larger Norwegian city of Trondheim and one from the mid-sized city of Bodø. While both policy packages reveal ambivalence in whether to facilitate or restrict car usage, the strategies employed in Trondheim to mitigate the effects of road building are stronger than those used in Bodø. In Trondheim, more resources are used for climate-friendly transport and stronger regulation is applied to integrate land-use and transport policy. In explaining this, different levels of state engagement are emphasised. The study reveals how, both financially and in the building of institutional capacity, the approach of national authorities prioritises the larger city.     

Can freeway traffic volume information facilitate urban accessibility assessment?: Case study of the city of St. Louis

In urban contexts, accessibility measures are often utilized to represent the interactions among land use, transport and people’s trips to services and other facilities. Accessibility is generally evaluated using conventional traffic measures such as travel time and distance, but traffic volume, which is a product of the travel trips induced by people’s needs, may also be positively related to accessibility. This study tests the hypothesis “can freeway traffic volume information facilitate urban accessibility assessment?” Traffic volume based accessibility models are proposed to investigate this relationship and test the hypothesis. The results indicate that the answer to this question is a qualified “yes”, as there is a statistically significant relationship between traffic volume differences and accessibility. The coefficients of the models can potentially be used as a reference to guide the urban planning process. The limitations of the proposed models can be addressed by deploying Intelligent Transportation Systems (ITS) traffic sensors on ramps and arterial roadways.     

Thinking regional and acting local: Assessing the joint influence of local and regional accessibility on commute mode in Montreal,Canada

Accessibility indicators, measuring the ease of reaching destinations via a specific mode of transport, are increasingly used in planning and research as they support integrated land use and transport planning. Research has shown that increased local accessibility (walkability for example) is associated with an increase in walking mode share, whereas increase in public transport accessibility is associated with a greater use of public transport. Yet, while public transport agencies are promoting the combination of active and public transport options to address one's diverse mobility needs, local and regional accessibility are rarely addressed together in research or practice. This research aims to determine the joint influence of local and regional accessibility on the transport mode used for work trips in the Montreal metropolitan region, while controlling for socio-demographic characteristics. Data come from the 2013 Origin-Destination survey 2016 Canadian census, 2017 public transport data DMTI Enhanced points of interests. A multinomial logistic model is used to understand how local and regional accessibility are associated with walking, cycling or taking public transport to work across individuals. The results demonstrate that increases in both local and regional accessibility are associated with a higher probability of using sustainable modes. The predicted probabilities suggest that local accessibility is more closely associated with a decrease in car use. This study sheds light on the interaction between local and regional land use and transport systems and is of relevance to planners and policymakers wishing to develop neighborhoods that support the use of sustainable modes.     

Accessibility modelling: predicting the impact of planned transport infrastructure on accessibility patterns in Edinburgh,UK

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.     

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.     

Development and test of the Perceived Accessibility Scale (PAC) in public transport

Perceived accessibility, defined as “how easy it is to live a satisfactory life using the transport system”, is proposed to be a complementary measure to conventional, objective measures of accessibility. Aiming at capturing the subjective element of accessibility, as opposed to conventional accessibility that is based on the same objective attributes for large areas or groups of people, the authors developed and tested a measure of perceived accessibility; the four items self-reported Perceived Accessibility Scale (PAC). In study 1, 237 users of public transport rated PAC. The results showed that PAC is a reliable measure. The PAC was further validated and proved reliable in two waves (study 2) in altered conditions (Wave 1, N = 246, Wave 2, N = 259). Based on this, an overall PAC index was constructed. PAC can be used to determine the traveler's (or possible travelers) opinion of accessibility in transport planning or accessibility-mapping, or for directing interventions aimed at improving accessibility to where they are best needed according to the individuals. Further development of the PAC and its potential within transport research and planning, and its future validation is discussed.     

Dynamic accessibility mapping using floating car data: a network-constrained density estimation approach

The concept of accessibility has been attracting increasing attention from transportation planners and researchers. The goal of “smart growth” is to promote accessibility rather than mobility. Accessibility mapping is a highly effective tool to support smart growth planning. Studies on accessibility mapping and analysis have proliferated over the last decade as Geographic Information Systems (GIS) has been widely adopted to produce accessibility maps. Nevertheless, a major negative aspect of these efforts is the lack of dynamic access measurement. Traffic conditions change significantly over space and time, leading to non-stationary travel time estimation which is central to accessibility measurement. In this paper, we propose a dynamic accessibility measure based on real-time travel speeds that are derived from floating car data (FCD). We introduce a novel integrated access measure to compute accessibility to Points of Interest (POIs) constrained by road networks. POI accessibility measures are obtained by means of both Network Kernel Density Estimation (NKDE) and Network Linear Density Estimation (NLDE). Therefore, we are able to capture temporal dynamics by taking into account speed variability using FCD during peak and off-peak hours on weekdays and weekends. We demonstrate that the proposed approach can capture the spatio-temporal dynamics of accessibility using FCD for Wuhan city in China. Empirical studies were conducted to examine the impacts of density estimation parameters (search bandwidths) and POI weights on the integrated accessibility. We find that search bandwidth and POI weights would impose profound influence on final accessibility values. Experiments also show that NKDE and NLDE would produce significantly different estimation results.