Origin of accessibility in the planning profession
Forms of Accessibility Measurement: 1950's to 1990's
Throughout planning thinking around the world is the increasing attention to sustainability in our communities, largely coming from the increased awareness of environmental and social issues, over the last 20 years. This focus on sustainability is opening up interest in accessibility concepts. The portrait of a region painted by accessibility measures, relate closely to the objectives expected when we talk of sustainability.
Up till this point, this paper has summarised various perspectives on accessibility and mathematical measures used to quantify accessibility. In comparison to the mobility analysis concepts and tools, accessibility is a more diverse concept. It is useful at this point to look behind the historical definitions and mathematical forms of accessibility to see if we can understand the questions the practitioners of accessibility were endeavouring to answer when they defined and applied this concept.
To further our understanding of these directions, it is useful to look at the meaning of accessibility and how it has been applied in the second half of the twentieth century. This exposition continues this look past the measures to the reasons for using them.
Accessibility: What questions are being asked?
Applications; 1960's - 1980's
Spatial Interaction Models
The Hansen observations and accessibility quotient, is considered the origin of spatial interaction models. The drivers behind this development are not clear, however, it is likely that it was simply to simulate the mechanism behind the location of residents in an urban area. Accessibility was the key determining variable, linking location of residents as a function of accessibility to employment. (Later, in 1965, he used accessibility in a model aimed at simulating the potential location of retail services.) The practical ease of application of spatial interaction models were realised, leading to an onset of research activity. With the rapid urban growth and increase in car availability in the 1960�s, this model type became in big demand.
In the early to mid 1960�s a number of land use models developed which utilised accessibility concepts as their basis of allocating land use. The Empiric Model, the Alonso model, the Herbert-Stevens model and the Lowry model. Of these, the Lowry Model of Metropolis (1964) has been the most recognised as contributing to the integrated land use and transport planning style of modelling. Lowry (1964) achieved a major land mark when he used economic base principles.
The purpose of these models is to �locate entities such as population, housing, employment and workplaces to spatial sub units or zones within a region�. The intention behind the models is mainly to forecast the likely trends in urban change, The Lowry model was used to obtain more reliable projections into the future of population and employment growth and distribution, by taking into account the spatial interaction of land use and transport. This has mainly been applied to long range planning, where the transport modelling does not have the need to be as complex as it does in short range mobility analysis. Sensitivity testing and policy analysis of scenarios is also an important use of the models. (ISGLUTI, 1990).
However, the short range mobility analyses models require as input, estimates of future land use patterns and have benefited from the long range analyses provided using the Lowry type models.
Before this period, land use and transport models developed separately. The classical four step transport model developed as an outcome of large scale transport studies in the United States (Chicago, Pittsburgh and Penn Jersey Area were particular notable).
Lowry provided mechanisms for the location of population and retail and service employment based on the location of basic industry and the level of accessibility of the various residential zones in the area (ISGLUTI, 1990). The original intention of the Lowry model appears to have been to simply represent the mechanisms of urban system behaviour, in particular, the mechanisms of urban growth and change (Hutchinson, 1984).
The Model of Metropolis provided no detailed representation of transport, while accessibility was based simply on direct distance. Later modifications of the Lowry model were made to enable it to model not only the changes in travel patterns which result from changes in land use and transport provision, but also changes in land use resulting from changes in the supply of transport. This was done by expanding Lowry�s approach and coupling it to the four step transport model (ISGLUTI,1990)
Some of the land use/transport models of the 1960�s and 1970�s were not intended to reproduce the behaviour of the urban systems so as to predict responses to policy (predictive type model). Instead, some models were framed to map out land use configurations that optimise some community objective such as energy efficiency. These models became known as �normative� or �optimising type models.
In the 1980�s an international review was conducted by a team that was known as the International Study Group on Land use/Transport Interaction. (ISGLUTI). A number of operational models that were of the above types were reviewed and their relative effectiveness assessed. Of interest to this discussion are the observations made on the models which used accessibility as part of the methodology.
The optimisation model Saloc, was partially representative of the Herbert-Stevens model (published 1960), which itself was a direct derivative of the Alonso model (published 1964). Saloc was observed to determine residential location based on accessibilities to exogenously determined employment patterns and also on accessibilities between households. It also only uses accessibility to destinations as the spatial determinant of location.
Osaka is an example of a predictive model in the Empiric tradition developed by Hill (published 1965). It utilises accessibility to employment in locating population. In the tradition of the Lowry type model, it endogenously locates non basic employment such as manufacturing on the basis of two accessibility variables. One is characterised by population or other employment, which constitutes the markets of the type of employment. The other variable is characterised by the services or goods it uses. Osaka also locates service employment partly on a general measure of accessibility to employment and/or population.
While Osaka and Saloc are not designed to forecast trip matrices, their accessibility indicators include assumptions about potential trip patterns. Saloc measures through the accessibility indicator, the average generalised cost of travel from each zone to a specified opportunity set of workplaces. A similar indicator for access to services and access to workplaces is also taken into account.
Wilson (published 1970) , according to ISGLUTI, systematised and made rigorous the gravity models used in the Lowry type models. The Dortmund model developed in the Wilson tradition, was analysed by ISGLUTI as representative of one of these model types. Accessibility is a factor in this model type, used for locating population, housing, jobs and workplaces.
In a monograph also of this period, Pirie (1978) attempts to clarify the confused understandings of accessibility at the time. Of interest here is the picture he paints of the applications. Accessibility is invoked as the purpose or goal of physical planning (by authors such as Owen 1972, Pahl 1975, Stone 1973, Schaeffer and Sclar 1975), it is used to explain ground rent and home location (Stegman, 1969), as a variable in trip generation and mode choice modelling (Stapler and Meyburg, 1975) and is used to partly explain real-income transfer (Harvey 1973; Pahl, 1975). Accessibility has become a key concept for characterising a fundamental principle of human activity (Karlquist, 1975).
Usefulness of accessibility at a very general level, as a design guide or as a language for exposition of a plan (G William 1972) is acknowledged. It also of interest to note that both G William and Karlquist comment that in the early to mid 1970�s, accessibility is not sufficiently developed as an instrument of appraisal, that more precise definitions are needed for it to be a useful tool for describing, explaining or predicting human organisation and behaviour.
By the mid 1980�s the application of accessibility indicators was being used to provide direct insight on travel behaviour on the basis that there is a close connection between accessibility and travel behaviour. For example Sheppard (1980) developed a model that showed travel demand as a function of accessibility to opportunities.
Hanson & Scwab (1986) challenged the certainty of this relationship. By applying a cumulative opportunity type of accessibility measure to the Swedish town of Uppsala, they produced some supporting evidence that the relationship between accessibility using this measure and trip generation ( in particular trip frequency ) is weak.
They also conclude that other aspects of travel behaviour i.e. mode use and travel distance are more strongly related to accessibility. Accessibility has been seen as a way to measure what is possibly the major function of cities. i.e. the provision of opportunities for easy interaction or exchange. Hanson and Schwab bring out that implicit in the applications discussed is the notion that there exists a fundamental and significant relationship between accessibility and actual travel behaviour, although as just discussed, they question the truth of this.
Concluding remarks of Pirie in his monograph poses the question � accessibility application depends on one�s conception, therefore can conceptions be wrong or only inappropriate?�
Convenience & Equity in distribution of opportunities
Black (1977) in the monograph �Public Inconvenience� utilised accessibility for the express purpose of measuring how conveniently activities of employment, schools, shops, health services, sport and recreation are located in relation to where people live. He furthermore used accessibility to seek answers to the question of whether the process of urban development has resulted in a �fair� distribution of facilities throughout the Sydney metropolitan region and to identify the transport problems that arise when residents have poor access.
The above question was able to be reduced to a number of component questions.
The overall hope of the study was to establish whether a particular pattern of urban development (with its implicit level of efficiency) is equitable for all residential groups or whether benefits are distributed to favour any identifiable groups within the population.
- How close are job opportunities, schools, shops, recreation and health facilities and services and how effective is the public transport?
- Does accessibility to these activities vary according to the neighbourhood�s socio-economic composition?
- Does good accessibility reduce the amount of travel residents make to various activities?
- What are the levels of accessibility for the young and the elderly, who must rely on public transport for all but short journeys on foot?
- Are there other groups in the community who are relatively disadvantaged because they do not have the mobility which a car provides? Disadvantaged is thought of as real penalties such as time, cost or ability to pursue an activity.
- To what extent have government policies been coordinated to meet the objective of improved accessibility?
- Should policies be aimed at bringing the services to the neighbourhood, improving the provision of transport to centralised services or some trade off between the two?
In the Sapporo, Japan case study (Black, Kuranami and Rimmer, 1982) the concept of accessibility was utilised to explore the equity of urban investments and whether some community groups receive benefits at the expense of others, that is the distribution implications of policy measures. It is noted that as policies have different effects on different locations and groups, then one way that the state can influence welfare, in addition to its income redistribution policies, is through the availability of public goods and services. An underlying question in this work is on the fairness of past and present policies of locating both public and private facilities and transport services on different groups within any community. Accessibility here is physical structure of an urban area, representing the total set of available opportunities.
The aim of the analysis was to quantify the internal structure of cities, the accessibility properties of each land use and transport system and to relate to the superstructure of each society. It was acknowledged that the outcome is a result of conflicting objectives of efficiency, equity and coverage for various social groupings.
Hanson and Schwab (1986) observed that accessibility measures were also being used to evaluate the distribution and quality of opportunities provided to urban residents. They also observed the application to gauge the equity of potential locations for public and private facilities (Knox 1978; Bach 1980; Jones and Kirby 1982) and to assess the net utility of alternative road networks (Koening 1980). They cite Dalvi (1979) as identifying the underlying interest in accessibility stemming from a concern for equity issues in making evaluations on transport plans, which up until the point, have mostly focussed on evaluating highway networks and speed alternatives in pursuit of increasing vehicular mobility of the population.
Applications; 1980's - 1990's
Sketch Planning and Integrated Transport Strategies
Banister (1994) provides an enlightening commentary on transport modelling from the 1960�s through to the early 1990�s giving the reader an understanding of position�s taken by practitioners in recent years. He suggests that the mid 1980�s began the demise of the conventional transport planning models (or classical four step model) in the sense that the desire became for a more focused approach, which takes particular policies or problems for analysis. That is a trend towards short term broad based analyses at the strategic level (simpler sketch planning) supplemented by detailed local studies. A return to the use of Integrated Land Use Transport Models, with their accessibility basis and simpler approach, as discussed early is suggested.
Banister(1994) comments that a series of conferences were held in the UK, Japan, Australia, France, Canada and the USA. This marked the switch, due to concern over the detailed, data intensive, classical four step approach, towards the use of a wider range of tools. However he also points out that while researchers had these reservations, if research did not fit the established framework, it was marginalised, losing the opportunity for improvement or diversification in methodology. Banister(1994) suggests that transport planning practitioners were able to resist previously theoretical arguments presented and put forward by political economists in the 1970�s and reacted when faced with these new research directions by taking refuge in more technical arguments with which they were familiar. Batty (1989), comments further that modelling has become institutionalised, retreated from the volatility of public policy making and has not responded to the challenge of social change.
Banister(1994) comments that the issue is the lack of attention to why transport demand changes, which relates to economic development, social policy, globalisation of economics, the increase in affluence and leisure and the use of technology. Linkages need to be drawn between transport and what is happening in society as a whole. Richmond (1990) suggests that traditional quantitative transport analysis be retained, but shifted off centre stage and replaced by a broader more critically oriented approach.
The underlying questions transport planners are needing to answer have shifted as social priorities have moved. Banister(1994) recounts that this is due to the shift in emphasis in the 1980�s from planning growth and providing for the car, to management of decline in urban areas, managing the use of car and utilising transport as a lever in regenerating economic growth in areas where there has been a shift to a post-industrial urban society. Processes have become more complex with industry restructure, communications and increasing linkages between transport modes. Banister comments that not only have the questions changed, but so have the answers.
Ortuzar & Williamson (1996) observe that the classic four step transport model is trip generation inelastic to the level of service in the transport system. An iterative process between trip distribution and assignment leaves trip generation unaltered. The major disadvantage of this is that changes to the network are assumed to have no effects on trip productions and attractions.
They comment that accessibility has been incorporated by some planners with the purpose of introducing elasticity to changes in the transport system, into the trip generation estimation.
Erlander & Stewart (1990) describe accessibility as a concept of opportunities on offer and introduce a related but different notion of �interactivity� as a concept of opportunities taken. Both accessibility and interactivity are seen as two of the long term goals society may wish to promote. They appear to be assumed as ends in themselves. No greater underlying question is identified, except that both are seen to relate to a more basic concept of a trip maker�s freedom of choice.
This may be a reflection on the emphasis on the mathematical, rather than the underpinning reasons or questions being sought, as identified by Richmond (1990) earlier in this discussion. This is not to detract from the focus of Erlander and Stewart(1990). In fact, their insights into the mathematical relationships between accessibility, interactivity and a third societal goal of efficiency through the formulas of Hansen, entropy and generalised cost (Erlander and Stewart, 1990) provide valuable insights to the potential approaches to further developments.
Throughout the 1990�s, Government bodies across the spectrum of transport and planning began to embody the goals of integrated transport and ecological sustainable development, into strategic plans. A number of planning documents have been produced that reflect the shift, identified by Banister (1994), towards short term broad based analyses at strategic level, detail local studies and integrated transport studies. The latter gained interest from late 1980�s and are characterised by statement need and vision on economic, environmental and quality of life aspects. Objectives are defined and both land use of transport strategies given on how the objectives are proposed to be met.
Integrated transport plans tend to be more qualitative than quantitative, therefore not requiring detailed modelling to take shape. Because of this, they do tend to reflect the longer term more so then the current application of classic transport modelling. A good example of this is the planning strategy put forward for the Sydney Region in 1993/94. Three companion strategies focusing on urban strategy, the road network ( throughout the state ) and an integrated transport strategy were developed by the NSW State Government.
Local government have also set about formulating integrated transport strategies, alongside the state or regional government. An example of this is the strategy formulated by the Sydney City Council ( Accessible City, 1995). The approach differs from previous strategies in that it approaches the whole transport question from the point of view of accessibility, not as only one of a number of objectives. More explicitly, the first steps were to visualise the city as it should be in terms of ease of access, both moving about within the city and in relation to getting to the city from neighbouring communities and regions. This picks up on the approach discussed about viewing where the city development ought to head. Sydney City Council has used accessibility to first shape the scenario it perceives the community would like to see in the city�s form, that is to visualise it and only then looks at strategies and programmes to form the framework for the years ahead.
Accessibilities may find a new role in analysis of post industrial cities. Duranton (1999) comments that the analytical perspective on cities is now reversed. Instead of taking for granted a cities propensity to grow, focus may well be on the remaining glue keeping cities together. In his monograph he notes that the analyse tools for post industrial cities have not been fully developed.
Macro Level Economic and Social Cohesion
Formation of the European Union in the past ten years and in years leading up to that point have led to a focus on spatial policy throughout the 1990�s. The European Regional/Spatial Planning Charter (Torremolinos Charter) in 1984 for the first time defined in a European context the notion of regional planning and its objectives.
Williams (1996) provides an account of this spatial policy development. The basic objectives are balanced socioeconomic development of regions, improvement of the quality of life, responsible management of natural resources and protection of the environment and rational use of land.
In 1987 the term economic and social cohesion came to signify a central underlying theme and motive for spatial policy development, with the aim of ensuing that disparities of wealth and quality of life between different regions of the European Union do not widen to the point of threatening the cohesion of the European Union itself. The European Union�s Europe 2000 report identified Trans European Networks as an important initiative in building spatial cohesion, a priority issue.
Rietveld & Bruinsma (1998) observe that the Trans European Networks are inspired by equity and efficiency principles. They observe that the networks are intended to provide access to the European Common Market benefits by regions of the member countries, making the connection to accessibility.
Williams (1996) comments that by 1991 European Union interest in spatial policy has moved its focus to include changes in spatial structure and relationships, particularly the growth of cooperation and networking between cities and regions. Williams ( 1996) cites a statement by the German Federal Minister for Regional Planning (Schwaetzer) in 1993 as an excellent summary of the underlying goals of spatial planning in the European Union.
"Strengthening economic and social cohesion of cities and regions, harmonious development of the community without blurring the identify of cities and regions and reduce disparities in the stage of development of different regions by improving their attractiveness and strengthening their locational advantage"
The Europe 2000+ report by the European Union in 1994 utilises accessibility to assess the relative advantages of regions as a result of choices available in transport and communications services.
Rietveld & Bruinsma (1998) reiterate the accessibility concept basis for the Lowry based integrated transport/ land use models. Comment is made that accessibility is a core concept in understanding the interface between transport and locational patterns of activities, but it depends on understanding the location decisions of investors in firms and users in their households.
They note that a characteristic of these models is their limitation to the spatial distribution of activity and incapacity to deal with the change in total population and employment. For example the question of whether an improvement in transport infrastructure in an urban area improves competitiveness so that it attracts more investments.
To answer this question, which is foremost in the thinking of communities of the European Union, it is necessary to form linkages between transport/land
use models, interregional trade and location models to compare the infrastructure quality in competing urban areas. Accessibility forming the basis of these macro models.
Rietveld & Bruinsma ( 1998 ) cite work by Newman & Kenworthy (1989) which emphasises the importance of density of land use as a key to transport demand and public transport success. It is emphasised that as well as density is the mix of activities, which relates to accessibility.
Accessibility is observed by Rietveld & Bruinsma ( 1998 ), to have a close relationship to urbanisation economies and agglomeration economies. The latter consists of localisation economies which accrue to firms of the same sector, because of being in close together, while the first is due to firms located in urban areas. They observe that the accessibility of the city with respect to itself ( internal accessibility) has a close relationship to agglomeration economies, an observation not previously noted. Urbanisation economies reflect higher productivity owing to closeness of markets for inputs and outputs. Accessibility essentially does the same thing but at a wider spatial range by including the markets in other cities. They point out that urbanisation economies are a part of accessibility. Accessibility, therefore is also observed as an important factor in regional or national production functions to represent transport services to production processes and to represent spatial spill over effects in production.
Williams (1996) summarises the drivers behind the Europe 2000+ report of 1995. The overall aim of balanced regional development is underpinned by three themes of competitiveness, viability and cohesion. Competitiveness is about both infrastructure availability and policy to reduce excessive growth of major conurbations and to encourage local development potential in all regions. Viability, introduced the sustainable development concept to economy, transport, urban environment and agriculture . Cohesion expresses concern with economic and social cohesion, or solidarity of the European Union by addressing issues of economic and geographical disparities,
peripherally and spatial and social exclusion. Williams (1996) emphasises that this policy development attempts to apply concepts of environmental sustainability and equity among social groups, localities and generations. Accessibility is listed alongside
peripherally, disparities of quality of life and economic prosperity as spatial problems that need to be addressed.
Wegener (1997) has applied accessibility in response to the above questions under the directive of the European Union. Aim of the work is providing methodology to give answers to the above questions under different scenarios of transport networks. Wegener, describes accessibility as the main product of a transport system. It determines locational advantage of a region relative to others, as a major factor of social and economic development and has a value by itself as an element of quality of life. The main purpose (or expectation) of the methodology is to identify the way transport infrastructure contributes to regional economic development in different regional contexts.
Obermauer & Black (2000) ask the question of what are the likely indirect effects on
land use and economic activity of implementing a major transport change such as a high speed rail system. They note, as does Wegener (1997) and Nakamura (1993) that accessibility is a necessary factor in a positive impact, but it is not the only factor. In analysing locational choice of firms, accessibility is an essential measure, but needs to be considered along with other factors such as local planning policies and subsidies.
Equity in distribution of opportunities
Nichols ( 1994 ) in his monograph on rural accessibility, reviews a number of Australian applications to rural communities. Most of these were with the purpose to provide a case for government funding of services to isolated towns or communities. He makes an insightful conclusion as to what purposes accessibility can contribute. For industry the question of where to position services, given a transport network, so as to maximise utility. For government as a provider of services there is the question of how to provide equity and access to services and government functions, or to identify how and to whom to provide compensation for lack of access to services or government functions. Two noteworthy suggested applications of accessibility were made. The first was �commercial services access provides a basis for arranging a companies geographical distribution of services to suit its market or could help identify locations for which alternative services could be provided.�. The second was to �provide a basis for compensatory mechanisms for accessibility
e.g. employment creation schemes or variations to unemployment benefits where opportunities for work are low.�
Cervero (1998) proposes the use of accessibility for giving attention to alternative strategies for reducing traffic congestion and mitigating environmental problems such as promoting efficient
land use development patterns and transport demand management. They help gauge progress towards other than mobility based regional objectives such as air quality and social equity. It gives a more balanced approach to transport analysis when used in conjunction with mobility based transport planning. Cervero (1998) uses longitudinal measures of accessibility (tracking accessibility changes) as social indicators, aiming to show distribution equity implications of past investments and planning decisions. It is pointed out by Cervero, Rood & Appleyard( 1999) that accessibility measures provide potentially useful insights into how evolving settlement patterns and
land use is influencing the demand for travel. Furthermore, in relation to sustainability, by linking shifts in regional accessibility to changes in vehicle kilometres
travelled per capita, air quality planning can assess the importance of land use management in reducing emissions.
In 1994 the State Road Network Strategy was provided in draft form to enable public discussion on proposed road network initiatives and the policy framework. Accessibility strategies were provided separately for urban and rural communities and is defined as � the ability of communities to readily and cost effectively access a range of activities, services and economic resources necessary for daily living. Mobility on the other hand is defined as the individuals freedom to move from one place to another. Accessibility to transport choices is included . In rural areas, access to services and activities, in the context of the relative disadvantages of rural areas, is important. An objective of this strategy is to seek social equity through accessibility. In this context , accessibility is seen to be about both efficiency and equity of access, including access to transport itself. Other objectives are prosperity, community health and safety and protection of the environment.
A vision for the Sydney Region was at the same time portrayed in the Sydney�s Future discussion paper ( 1993). The vision statement itself used the terms dynamic, sustainable and diverse community, leaving a rather fuzzy understanding of its meaning. However, goals supporting the vision are more specific, namely equity, efficiency, environmental quality and liveability. Accessibility is seen both implicitly and explicitly in achieving a number of these goals. Implicitly, through equitable availability of urban resources, opportunities for all sectors of the community, an efficient spatial metropolitan structure as it relates to the location of activities, employment, recreation and human activities. Also through opportunity for diversity in employment and for people to enjoy happy and fulfilled lives.
Explicitly, through equitable access to employment, housing, education, health services and recreation and liveability through a sustainable, comfortable and healthy environment with good accessibility. The notion of relationship between communities ( Sydney, Wollongong and Newcastle) is emphasised. Accessibility has been used in this context to contribute in providing a framework in which policies and actions of a number of government agencies can form. The third companion strategy, the Integrated Transport Strategy (1993), presented a number of related objectives, with an accessibility component. Social equity included the need to provide infrastructure and services which maintain transport opportunities for all sectors of the community. The objective of environmental protection ( or sustainability ) interestingly included the need to improve accessibility while minimising pollution. This strategy defines accessibility as � the business of getting there with minimum effort and at an affordable economic cost.� It is emphasised, that governments throughout the world faced with increasing population and car dependency, are reviewing transport strategies with a view to improve the
liveability of cities. Under threat is the accessibility to services and facilities, if trends continue. The driving reason here, for the interest in accessibility, is the risk current urban trends pose to the urban environment and risk of exceeding government capacity to provide appropriate social and physical infrastructure. It is suggested that the focus on mobility and lack of focus on accessibility, has let us down when it comes to seeing the overall direction of our cities development and where it ought to be heading. Differences in ability to use services and facilities or variations in accessibility is seen as a concern in terms of the inequity, for example in a city such as Sydney with its high car dependency and low density development. Environmentally the structure of Sydney is seen to have outgrown its public transport network. The lack of accessibility to public transport in the fringe growth areas ,
fuelling the high level of emissions from growth in long trip lengths by car. The Government of Victoria followed a similar path to NSW, introducing in 1996, a strategic framework for an integrated transport system in Melbourne ( Transporting Melbourne, 1996), together with the Living Suburbs strategy. Transporting Melbourne provided very similar frameworks, though Melbourne specific initiatives. A particular reason for accessibility that comes out of this strategy, is the effect on the competitiveness of industry.
Western Australia is following similar path. In 1999 � The Transport Infrastructure Project, a Framework� outlined the intention to provide a vision and a process to, amongst other objectives, extend transport access. Accessibility is seen in the document as contributing to equity of access to opportunities, goods and services between regions, demographic groups and economic sectors. The purpose behind the framework is the improvement of quality of life and competitive industry.
In 1999, the NSW Government issued the Action for Transport 2010 integrated transport plan for Sydney and for regional NSW. Its depth of discussion was not as detailed as the 1993 strategy , but included the same general objectives based on accessibility. It was more a compendium of infrastructure initiatives, follow on from the strategy framework in 1993. Accessibility is largely used to focus attention on access improvements to transport services. In both NSW and Victoria in the late 1990�s, has been increasing community concern in rural areas of the lack of accessibility they have to services, transport and employment. Many areas have reached a point where survival of the community is in question. The Government of Victoria and the NSW Government released draft integrated transport strategies for rural communities ( Transport Victoria, 1998 and Action for Transport 2010, 1999). The level of concern in the communities in strong political impacts. The change in state government in Victoria in 1999, was strongly influenced by discontent in rural communities. A number of initiatives to improve access between rural centres such as Ballarat , Geelong and Bendigo to the Melbourne region became part of the election platform and are being developed today.
Network Infrastructure Performance
Rietveld & Bruinsma (1998) highlight the relationship between accessibility and the network character of infrastructure, which is more prevalent today with intermodality of transport. A distributive effect occurs when an accessibility improvement in a section of a transport network has a negative effect in another part. Generative effects refer to the net improvement that accrues across the total transport network when an improvement in accessibility is made to a section. These questions are of particular interest to providing insight on the transport configurations and the role in strengthening European Union goals of economic and social cohesion.
Berquin (1998) utilises accessibility to attempt to determine how fast, a transportation system allows passengers to travel in Brussels. Berquin introduces the concept of network accessibility as the average time of any trip on the network. The goal of the approach is to pinpoint easily the strength and weakness of a transit network. By comparing analyses four years apart, the gains or loss in accessibility are observed and linked to particular transport system initiatives
Matching Business To Neighbourhood
One �real time� application that is detailed by Tolley and Turton (1995) is the adoption of a policy by Dutch planners with the purpose of matching the mobility profile of a new business with the accessibility profile of a neighbourhood.
Applications; 2000 - 2001
Locational Decisions For Individuals And Business.
Olaru and Dragu (2001) demonstrate how accessibility measures might be used in location decisions and investment policy and how important to residential choice are the travel
opportunities, and how much this choice is a life-style choice (delight in the place). They emphasis that the spatial distribution of accessibility, particularly changes in accessibility can tell the planner or policy analyst directly who are the �winners and losers� in a given scenario.
Relationships between residential housing construction and location factors were analysed by Wagtendonk & Rietveld (2000) Guers and van Eck (2001) report that these researchers found significant causal relationship with job accessibility and to a lesser extent accessibility to nature areas. But it was not as significant as the influence of existing residential patterns and land use policy.
Guers and van Eck (2001)observes the work of Cervero(1997) who in reviewing the BART rail system and surrounding communities, shows accessibility having
consistent impact on land values. Wagendonk and Rietveld (2000), found that the close proximity to road and rail infrastructure lowered residential construction whilst closeness to access points to highways and rail stations increased residential construction. Guers and van Eck (2001), conclude that in general locational preferences and location choice of households and firms are partly driven by accessibility. However, characteristics of the individual households and firms and building are more important.
Sustainability of Cities
In a study on Chinese cities, Black (2001) concludes that accessibility has an important role in the desire for a sustainable city form. Chinese cities like many Asian cities are under pressure to take on contemporary trends seen in western cities in the past 40 years. Under the pressure of increasing motorised transport and increasing separation between work and home, these cities would be at great risk of suffocation.
Accessibility to land uses is said to be unanimously agreed ,by advocates of more sustainable western cities,
as a key objective and performance measure for an equitable city of the future.
The Netherlands Ministry of Housing, Spatial Planning and the Environment commissioned in 2000 a review of accessibility measures and their applications. The study focused on both accessibility measures as intermediate indicators for the evaluation of impacts of changes within the
land use /transport system , for impacts outside this system and accessibility as an economic and social indicator.
Three types of accessibility measure are identified, infrastructure based, activity based and utility based. Examples of the first type include level of congestion on the road network and provide valuable information on the level of service of infrastructure in a particular area. Activity based measures such as potential accessibility include the efficiency of transport network and
land use patterns together. The study by Geurs and van Eck (2001) reports that a number of authors in the mid to late 1990�s established relationships between potential accessibility and trip lengths (Handy (1994) inverse relationship to shopping distances; Levinson (1998) inverse relationship to work trips). A similar relationship was observed to vehicle kilometres / person ( Handy (1994) inverse relationship to combined trip frequency and trip length.; Kockelman (1997) inverse relationship to household vehicle kilometres).
Guers and van Eck (2001) draw attention to the non user benefits that may arise from accessibility. An option value and bequest value for others and future generations. However they observe that it would be difficult to actually quantify this into an economic value.
Guers and van Eck (2001), identify the application of accessibility to assess the economic impacts of change in transport system and
land use. The social cost- benefit analysis approach to accessibility has as its objective, the estimation of consumer surplus. Accessibility can be related to consumer surplus and consumer welfare from micro economic welfare theory. Consumer surplus is estimated using the difference between two accessibility scenarios using a utility based accessibility measure( the net benefit people achieve from accessing opportunities). Utility based accessibility measures are the only type of accessibility measure which is suitable for economic evaluation of user benefits.
A production function approach is used to gauge the wider economic benefits coming from accessibility. In the production function, transport infrastructure is considered as a capital stock available to a region. Specific sectors of the
macro economy are analysed for impact by infrastructure on the performance, in terms of Gross Domestic Product. An application is to use this approach for analysing the economic impact of infrastructure expansion, giving an aggregate view of the contribution to production. However the relationship is complex and presently rather rubbery. The authors suggest a third approach of measuring economic impact of accessibility through employment effects is raised but not considered robust at this stage, more a temporary or distributive effect.
Geurs and van Eck (2001) observe that activity and utility accessibility measures form a useful tool in social evaluations . Social impacts can be categorised into three groups, namely the level of access to opportunities, equity issues and impacts on lifestyle of individuals or groups of individuals ( e.g. health problems, safety, social relationships). The authors focus on the first two of these with little discussion on the third.
Opportunities, or changes in the level of access are one current application. The other current application is equity, or the distribution of access to opportunities among societal groups. Equity can be thought of in terms of the difference between equalisation of opportunities and outcomes. Equity can
also be divided into two types. Horizontal equity which focuses on fairness of cost and benefit allocation between individuals or groups with comparable needs, resources and abilities and Vertical equity which focuses on allocation between groups with differing circumstances. Geurs and van Eck (2001) observe that vertical equity can be partitioned into spatial , social and economic equity. Spatial equity focus is on distribution of activities in
space, the authors observing the relationship to previous work on territorial justice. Social equity focus is on needs and
abilities for access based on specific characteristics for the individual or group, the authors
observing the relationship to previous work on social justice. Economic equity focus is on the affordability, due to differing resources, levels of income or wealth of individuals. It is not the same as economic evaluation, but rather the differences in levels of access to certain opportunities instead of their monetary valuation.
Public Transport System Performance
Viegas (2001), observes that there are three main aspects to making up the performance of public transport systems. Productive efficiency, which covers the transformation of basic resources into transport production (vehicle.kms). Network design, covers the correspondence between those units of transport production (vehicle.kms) and the accessibility levels in the various parts of the territory served. Commercial effectiveness, covers the potential represented by the accessibility levels into real consumption of public transport by its clients (passenger.kms) and the revenue generated.
The reader has been shown that through the 1960�s and 1970�s accessibility is seen to be a popular notion in seeking to establish links between land use location and transport. Dominant drivers of the day were planning for car usage and urban growth. Classic transport 4 step models dominated the transport planning approach, with accessibility based models being applied to longer term sketch planning and policy testing.
Accessibility is also applied through the 1970�s and 1980�s to questions of equity in terms of spatial distribution to attempt to bring out the fairness in facilities policies amongst social groups in communities.
By the mid 1980�s, the objectives for urban planning has shifted more from planning for car usage and urban growth to planning for car management and reconfiguration of urban communities and industry. Accessibility and accessibility based sketch models became a potential �centre stage� contributor, with the classic four step transport model lowered in its predominance. Questions have shifted to be more about understanding of community drivers of transport demand than in the past. With increasing complexity in community interactions, the new answers to the questions are also being recognised. Accessibility is seen as having an influential role in increasing the sensitivity of the classic four step modelling to network changes.
Macro level application has taken a central role where the restructuring of countries and regions is taking place, as can been seen in the European Union. Questions of economic and social cohesion and regional competitiveness are seen to be a highly important focus for these communities.
Accessibility throughout the1990�s has been applied in a qualitative way to defining objectives and frameworks of integrated transport strategies, at all levels of government. In some cases it is used to construct a picture of the city structure to form a fully formed vision of where the transport strategies and programs need to head.
The focus in application at the current time continues to be on providing insights into urban and regional locational choices by individuals and businesses, together with economic and social performance of cities and their transport infrastructure. At the 2001 World Conference of Transport Research (Seoul, Korea), half of the papers put forward contained references to accessibility. In comparison with world research effort of the mid 1990�s, where much of the focus was on mobility and its relationship to sustainability, there has been a significant shift by 2001 towards accessibility and its contribution towards sustainability in city and regional form , economies and communities.
The concept of accessibility as it has been applied over the past 40 years while fitting the purpose of the practitioner, reflects the
bureaucratic and community aspirations of the time, though the relevance to policy has depended on how well these three have lined up. The most important role of the accessibility concept remains that highlighted in the account at the beginning of this paper. Accessibility is about opportunity made available to the recipient by others. The choice to take it up, is dependent on the recipient, making that choice. The opportunity is at its most underlying level about relationship, whether directly through fellowship with other people, or indirectly through the
outworking of connection to services, goods or employment.
As a footnote, lack of relationship, coming from inaccessibility, is viewed as inequity, which it is , but a person�s response to this is not necessarily a loss. A person can grow in adverse situations, as they can in situations where positive opportunity is available. This is not to say the planner should seek to structure in inaccessibility in order to do this. On the contrary, we should seek to improve the opportunity for relationships to grow through improving accessibility, but recognise that inequity in opportunities can also be overcome by a person�s personal growth through facing obstacles in life.
In the context of what has been explored in this paper, this historical unfolding of the role of accessibility, to the present position where we find a call for reapplication of transport process and the models to match current community expectations and dynamics, gives credence to research focussed on integrating accessibility more fully into the planning process. It is worth noting the insightful words of Moseley (1979) who observed that the quality of life is much more closely linked to accessibility than mobility and therefore a much more valuable objective for the planning process.
Geurs and van Eck (2001) conclude that the relationships between infrastructure improvements,
accessibility and economic development are theoretically complex and empirical evidence is still weak and disputed. Rietveld & Bruinsma (1998) comment that a promising approach to productivity analysis is where the contribution of infrastructure is measured by the services provided by the stock (accessibility) rather than by the stock of infrastructure itself.
The SASI model (Schurmann, Spiekermann, Wegener, 1997), bases production functions on economic structure, labour force, endowment indicators and accessibility indicators. Better representation of transport system characteristics in this analysis process presents opportunity to give the decision makers a process to more clearly see the macroeconomic effects of system changes. It is also important to note the potential for the endowment indicators, which are used to measure the suitability or capacity of a region for economic activity in terms of educational skills , natural conditions to further focus the analysis towards ecological sustainability. Inclusion of ecological capacity here provides a filter for exclusion of excessive levels of economic activity from the outset in the analysis.
Bringing together the threads of the comments of the above authors and my own inclinations, a number of important research areas can be defined as follows:
- Accessibility is strongly related to transport system characteristics and its spatial configuration �network effects�. There is a need for greater sensitivity when it comes to representing the transport supply characteristics coming from the newer innovations.
- The concept of accessibility, is largely under represented in current transport system
modelling practice. The shift in community expectation in recent years opens up the need to develop greater overlap between mobility and spatial interaction models. This needs to be quantifiable and conceptually relevant. The body of work on accessibility, now used for separate performance evaluation is believed to be the key concept in providing this integration.
- Increased complexity stemming from 1& 2 will require the development of reporting processes that enable decision makers to make well informed decisions, without being overpowered by the quantity of information.
- Case study testing the estimation of consumer surplus in social cost benefit analysis through the application of accessibility based techniques, given research stemming from 1. & 2. Further develop guidelines incorporating this methodology.
- Case study testing the estimation of productivity through the application of accessibility based techniques, given research stemming from 1. & 2. Research need to include system characterisation in terms of service level in the form of accessibility. Further develop guidelines incorporating this methodology.
- The economic assessment process needs to incorporate more fully the methodology of sustainability. Specific focus areas include the inclusion of ecological capacity as an endowment parameter filter in the production function . Similarly, the inclusion of ecological capacity in limiting the opportunities available when quantifying accessibility measures. Inclusion of regional survivability in more rural areas as a function of accessibility needs exploration.
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