Glossary

The Glossary of the Action “Accessibility Instrument for Planning Practice” was born in order to create a common language/understanding between all the participants of the Cost Action. To reach this goal, all members of the Action were involved in choosing the terms to define and their meanings in a participatory way. The Glossary of the Action is not static but a dynamic source of continuous debate. It is the result of a collaborative process started in the early stage of the Action.

A baseline document for further discussions was proposed during the first stage of the work of the Action, in order to better explain the accessibility instruments survey (see Hull et. al., 2012) and it was published in the action website during the first year of work. This document received several comments by the action members suggesting to add, eliminate or modify some terms. Based on this web discussion, a first version of the Glossary was produced and published in the first Report of the Action (Papa and Angiello, 2012).  As the authors stressed, the first version of the Glossary was not supposed to be a final product, but the first step of a continuous process. Keeping this in mind, in June 2013, during the second Summer Training School in Tui-Valença, the Junior Research Network of the Action launched a debate in order to wider the previous version by including a broader range of new terms. The work here presented resumes the main conclusions of this collaborative process.

 

Accessibility (evolution of the definition)

  • “the opportunity which an individual or type of person at given location possesses to take part in a particular activity or set of activities” (Hansen,1959).
  • “the average opportunity which the residents of the area possess to take part in a particular activity or set of activities” (Wachs and Kumagai, 1972).
  • “the accessibility of a point in a system is a function of its location in space with respect to all other points in the system” and “implies relative nearness either in the sense of a direct linkage or a minimum expenditure of travel cost or time” (Hack, 1976 and de Lannoy, 1978).
  • “the consumer surplus, or net benefit, that people achieve from using the transport and land-use system” (Leonardi, 1978).
  • “the ease and convenience of access to spatially distributed opportunities with a choice of travel” (U.S. Department of Environment, 1996).
  • “the extent to which the land use-transport system enables (groups of) individuals or goods to reach activities or destinations by means of a (combination of) transport mode(s)” (Geurs and van Eck 2001);
  • “ the amount and diversity of places that can be reached within a given travel time and/or cost” (Bertolini, LeClercq and Kapoen, 2005).
  • “the ease in meeting one’s needs in locations distributed over space for a subject located in a given area” (Cascetta, Cartenì and Montanino, 2013).

Accessibility instrument

A tool that aims to provide explicit knowledge on accessibility to actors in the planning domain, a tool of measure, interpretation and modelling of accessibility, developed to support planning practice (analysis, design support, evaluation, monitoring etc.). Mostly, it consists of computer model(s) that transfers data/information about urban systems into meaningful knowledge, by providing visualization tools such as maps or numerical indicators. Accessibility Instruments can be (Papa and Angiello, 2012):

  • Measuring attributes of places or people – e.g. planning tools to identify how to make places more liveable or ways of identifying the opportunities available to people when planning new facilities or destinations;
  • Analytical methods to apply accessibility principles within planning – e.g. parking policy standards based on accessibility criteria or public transport service delivery requirements based on people’s accessibility needs;
  • Models to understand dynamic effects and connectedness in transport networks, in particular the dynamics between spatial plans and transport investments;
  • Indicator calculation methods where indicators are used to audit, monitor or set standards for planning policies.

Accessibility Measures

Accessibility measures are used to translate the concept of accessibility in quantitative indicators that take into account both the socio-economical and the transportation systems (Papa and Angiello, 2012). Each accessibility measure has a general conception and a general formulation of its accessibility indicator (infrastructures-based measures, contour measures, gravity measures, competition measures, utility-based measures, network measures, time-space measures). 

Active Accessibility

Active accessibility of a certain zone  is a proxy of the ease of getting to the activities located in different zones  of the study area for a given purpose (e.g. workplace, shopping), moving from  (Cascetta, 2009).

Competition Measures

These measures are able to consider the effects of competition in the origin and/or destination. The effects are usually located in urban areas where competitiveness concerns or users seeking opportunities and/or opportunities competing for users, when users are insufficient to enable the range of opportunities (Silva, 2008). The measure calculates all potential users of an activity in an area as well as all potential activities, trying to balance the relationship between the number of users and activities. 

Components of accessibility

In Geurs’ and van Eck’s (2001) understanding, accessibility consists of four components:

  • Land use component (of accessibility) – The land-use system, consisting of the amount, quality and spatial distribution of identifiable opportunities.
  • Transportation component (of accessibility) – The transport system, expressed as the disutility for an individual to cover the distance between an origin and a destination using a transport mode.
  • Individual component (of accessibility) – The needs, abilities (depending on people’s physical condition, availability of travel modes, etc.) and opportunities (depending on people’s income, travel budget, educational level, etc.) of individuals.
  • Temporal component (of accessibility) – The availability of opportunities at different times of the day, and the time available for individuals to participate in certain activities.

Furthermore, these components may be affected by accessibility through feedback mechanisms. 

Contour Measures

(also known as cumulative opportunities or isochronic measures) count the number of opportunities/activities available within a given travel time, distance or cost (fixed costs), or measure the (average or total) time or cost required to access to a fixed number of opportunities/activities (fixed opportunities) (Geurs and van Eck, 2003). 

Decision Support System (DSS)

A computer-based information system that supports decision-making activities. DSS serve the management, operations, and planning levels of an organization and help to make decisions, which may be rapidly changing and not easily specified in advance. (Papa and Angiello, 2012). 

Gravity Measures

Are based on the concept of attraction and impedence. These measures assumes that accessibility of a given zone  is proportional to the attractiveness of destinations surrounding (e.g. the distribution of population, employment, income, etc.) and inversely proportional to the spatial impedance of travel required to reach those destinations (e.g. travel time, distance, generalized cost etc.) from all other zone of the study area. 

Infrastructure-based Measures

These measures mainly focus the characteristics of the infrastructure and analyze the performance of the transport system as a whole.

Mobility

The mobility concept is understood by the movement (or flow) of people, goods and information (also considered as “virtual mobility”) corresponding to relocation needs. This concept assumes that the mere increase of “travelling miles” or speed between two points benefits people, however does not take into consideration the distribution of opportunities in the territory. Mobility and accessibility are considered the “ying and yang” of planning (Ross, 2000).

Network measures

A group of measure based on graph theory and network analysis that correlate accessibility with topological measures of the transportation network. In some case this measures can include also the land use component of accessibility (Papa and Angiello, 2012).

Passive Accessibility

Passive accessibility  is a proxy of the opportunity for a certain activity located in the zone  of  being reached by the potential “users” coming from all the other zone of the study area for a given purpose (e.g. the clients of a shop) (Cascetta, 2009).

Perceived Opportunity Measures

The number of opportunities perceived by an (average) individual for satisfying his/her needs in the study area (Cascetta, Cartenì and Montanino, 2013).

Place Rank Measure

Place Rank measure is based on the methods used by search engines such as Google to rank Web pages. This measure assume that the level of accessibility in a certain zone  of the study area is determined based on the number of people coming to this zone to reach an opportunity, where each person contributes to the accessibility level in the zone to which he commutes with a different power. The power of the contribution of this person depends on the attractiveness of his/her zone of origin as final destination (El-Geneidy and Levinson, 2006). 

Planning

Planning, as a general activity is the making of an orderly sequence of action that will lead to the achievement of a stated goal or goals (Hall, 2010).

Planning Support Systems (PSS)

PSS is a subset of geoinformation-based instruments that incorporate a suite of components (theories, data, information, knowledge, methods, tools, etc.) that collectively support all of, or some part of, a unique planning task (Geertman and Stillwell, 2003).

Spatial separation measures

Measures travel impediment or resistance between origin and destination, or between nodes. Travel impediment measures can include: Physical (Euclidean) distance Network distance (by mode), travel time (by mode), travel time (by network status—congestion, free-flow, etc.), travel cost (variable user cost or total social cost)   (Curtis and  Scheurer, 2010).

Statutory planning

The part of the planning process that is concerned with the regulation and management of changes to land use and development. (Wikipedia)

Time-space measures

Measures travel opportunities within pre-defined time constraints. (Curtis and Scheurer, 2010)

Urban Simulation

Use of a wide range of modeling concepts to capture and reproduce any type of physical or socioeconomic phenomena observed in urban systems, allowing the forecast of potential evolutions under controlled conditions to assist planning or decision-making processes in general (Papa and Angiello, 2012).

Usability (of an instrument)

A qualitative indicator of the extent to which an accessibility instrument is accepted and applied in planning or decision making process by its end-users (Papa and Angiello, 2012). 

Utility-based Measures

Measures individual or societal benefits of accessibility. This can occur in monetarised form as a measure of economic utility, or as an indicator for social equity (or for other sustainability objectives). It can also be applied as a behavioral indicator, measuring the value individuals afford to the accessibility of particular activities (Curtis and Scheurer, 2010).

References

Bertolini, L., Le Clercq, F., & Kapoen L. (2005). Sustainable accessibility: a conceptual framework to integrate transport and land use plan making. Two test – applications in the Netherlands and a reflection on the way forward. Transport Policy, 12, pp 207-220.

Cascetta, E. (2009). Transportation systems analysis: models and applications. Second edition. Springer.

Cascetta, E., Cartenì, A. & Montanino, M.(2013). A new measure of accessibility based on perceived opportunities. Procedia – Social and Behavioral Sciences, 87, pp. 117–132.

Curtis, C., & Scheurer, J. (2010). Planning for sustainable accessibility: developing tools to aid discussion and decision-making, Progress in Planning, 74 (2), pp.53-106.

Department of Environment, 1996. Policy and Procedure Guidelines. PPG 6.

de Lannoy, W., & van Oudheusden, D. (1978). The accessibility of nodes in the Belgian road network. Geojournal, 1978, 2 (1), pp. 65-70.

El-Geneidy, A. M., & Levinson D. M. (2006). Access to Destinations: Development of Accessibility Measures. No. MN/RC-2006-16. 2006.

Geertman, S., de Yong, T., Wessels, C., & Bleeker, J. (2004). The relocation of ambulance facilities in central Rotterdam, in Stillwell, J., & Clarke, G. Applied GIS and spatial analysis. London. John Wiley & Sons Ltd.

Geurs, K. T., & van Eck, J. R. (2001). Accessibility measures: review and applications. Evaluation of accessibility impacts of land-use transport scenarios, and related social and economic impacts. National Institute of Public Health and the Environment.

Geurs, K. T., & van Eck, J. R. (2003). Evaluation of accessibility impacts of land-use scenarios: the implications of job competition, land-use, and infrastructure developments for the Netherlands. Environment and Planning B: Planning and Design, 30(1), pp.  69-87.

Hall, P. (2010). Urban and Regional Planning Fourth edition. London. Routledge.

Hull, A., Papa, E., Silva, C., & Joutsiniemi, A. (2012). Accessibility instruments survey in Hull, A., Silva, C., & Bertolini, L. (Eds.) Accessibility Instruments for Planning Practice. Report 1. COST Office, pp 205-238.

Hack, J S. (1976). Land use transport interaction – a new approach to accessibility. Development Plans Regional Strategies 2 Division, Department of the Environment, Working Note No 151. London.

Hansen, W. G. (1959). How accessibility shapes land-use. Journal of the American Institute of Planning, 25, pp. 73-76.

Leonardi, G. (1978). Optimum facility location by accessibility maximising. Environment and Planning A, 10, pp. 1287 – 1305.

Papa, E., & Angiello, G. (2012). Glossary in Hull, A., Silva, C., & Bertolini, L. (Eds.) Accessibility Instruments for Planning Practice. Report 1. COST Office, pp 253-266

Silva, C. (2008). Comparative accessibility for mobility management. The structural accessibility layer. Ph.D Thesis. Faculty of Engineering of Oporto.

Ross, W. (2000). Mobility & Accessibility: the yin & yang of planning. World Transport Policy & Practice, 6 (2), pp. 13-19.

Wachs, M., & Kumagai, T.G. (1973). Physical accessibility as a social indicator. Socioeconomic Planning Science, 7, pp. 327-456.

Comments

  1. Avatar of Derek Halden

    Derek Halden

    October 24, 2011

    Accessibility – The ability to reach desired goods, services, activities (together called opportunities) and the ability of destinations to be reached by people and goods (sometimes called catchments)
    [I SUGGEST DELETING ALL TYPES OF MEASURES AS THE LIST IS PARTIAL AND POTENTIALLY MISLEADING]
    TIME Contour measures…………….
    OPPORTUNITY Contour measures are also common which are the travel time to reach a threshold number of opportunities – these are particularly important in activity analysis) ]

    Gravity measures [I don’t agree with the definition at all – continuous measures are the normal term to distinguish from contour measures. Gravity measures are something quite different that include terms of attraction at each end as well as a measure of separation]

    Indicator – The way in which accessibility is expressed.

    Personal capabilities – (of accessibility) The needs, abilities (depending on people’s physical condition, availability of travel modes, income, travel budget, educational level etc.)
    [Opportunity measures? - and the opportunities available to individuals.[

    Land use component - (of accessibility) The land-use system, consisting of the amount, quality and spatial distribution of identifiable opportunities.
    [MANY LAND USE PLANNING SYSTEMS DO NOT HAVE A BASIS IN EITHER EFFICIENCY OR ETHICS] Land use planning – Encompassing various disciplines which seek to order and regulate land use in an efficient and ethical way. (Source: wikipedia)

    Network measures – [THE DEFINITION IS TOO VAGUE TO BE HELPFUL AND i THINK IT SHOULD BE DELETED LIKE THE OTHER TYPES OF MEASURES THAT ARE ILL DEFINED - how many friends a person has on facebook might be a personal capability network measure, and the physical networks omits e-networks. Even for physical networks the definition is unclear since ‘route segments’ is very pejorative.]

    Sustainable [CAN WE SAY ACCESSIBILITY BY RENEWABLE ENERGY IF WE MEAN THAT AND ACCESSIBILITY BY WALKING IF WE MEAN THAT - SUSTAINBILITY IS NOT WELL ENOUGH DEFINED FOR A GLOSSARY] accessibility – the amount and the diversity of activity places that people can reach within a given travel time and/or cost with as little as possible use of non renewable, or difficult to renew, resources, including land and infrastructure. Bertolini, Le Clercq & Kapoen, 2005

  2. Vesa Kanninen

    October 25, 2011

    First, I would suggest developing this glossary not towards textbook-definition but towards a bit more comprehensive definitions. I feel that the aim should be better understanding of the concepts. Hence, the definitions, while still concise, could incorporate various aspects of the terms in question. This would also enable better explanations of the measures and components. I understand that this, or course, is a more time- and resource-consuming direction, but maybe in the next version we could divide that task and then have another round of discussion? The definitions could also be on two levels: first, the “lowest common denominator”-type; second, a more elaborated version with more “tones”.

    Second, I agree with Derek’s views on “land use planning” and “sustainable accessibility”. However, given my first point, I’d work with including a bit of theory and normative aspects into the definition, thus giving it more depth and content. As for sustainable accessibility, while Luca&al are certainly correct in practical terms to say “as little as possible”, for me that sounds fully context-dependent, which in my mind cannot be the starting point for a definition of a normative concept including “sustainability”.

    Third, I would suggest adding a “Perceptional component” to the list, with a definition revolving around the idea that perceived accessibility is often important in determining a) mode and destination choices and b) the outcomes of planning decisions. The definition should include the idea that it’s about perceived time, perceived ease, perceived cost, perceived quality and perceived culture – that (together or separately) form a sometimes difficult-to-measure yet tangible component to “accessibility”. The perceptional component also has different foci at different spatial scales. I understand that only parts of this can go into computer models or DSSes.

    • Avatar of Marco te Brömmelstroet

      Marco te Brömmelstroet

      October 25, 2011

      I agree with your idea of more elaboration as a second type of glossary. This one is to get on one line on what we all think are the main elements of the Action (e.g. accessibility and instruments). In e-mails and meetings these terms seem to have a wide range of understandings and we need to get a common denominator to keep the Action moving forward. Could you then respond to the terms here (or propose new ones) with a common denominator view? With the note that more nuance will come in a later stage?

      • Vesa Kanninen

        November 2, 2011

        Well I’ll give it a shot:

        Interpretability – the degree to and the ease with which an accessibility measure can be made understandable outside its original context.

        Opportunity component (of accessibility) – dealing with the (qualities of the) desired goods, services, activities and destinations (together called opportunities) as objects to the study of accessibility.

        [I would rather have this as a separate entry than keep it within land use component, since it has more in it than can be read from the land use component definition. It is important not to lose sight of where one's headed ;]

        Perceptional component (of accessibility) – dealing with the perception (by an individual/people) of other components of accessibility; concerning individual subjective measures of availability and attraction of opportunities.

        Perceptional measures – measures the subjective availability and attraction of opportunities within given spatial, temporal, social or other accessibility-related constraints.

        I think the entries are, for the purpose you outlined, quite fine, overall, if/when/since we indeed stick to pragmatic interpretations that aim at reaching common understanding within this “accessibility instruments” framework of TU1002.

  3. Luca

    October 26, 2011

    It is admittedly a pragmatic rather than a rigorous definition, but this is how we have defined ‘Accessibility Instruments’ in the guidance for the report that the Working Units are making on own accessbility instruments. It is based on the initial action proposal, but importantly, as amended after presentations and discussions at the last WG2 meeting in Edinburgh, with ‘inlcusiveness’ as an important citerion.

    “Accessibility Instruments can be:
    1. Measuring attributes of places or people – e.g. planning tools to identify how to make places more liveable or ways of identifying the opportunities available to people when planning new facilities or destinations.
    2. Analytical methods to apply accessibility principles within planning – e.g., parking policy standards based on accessibility criteria or public transport service delivery requirements based on people’s accessibility needs.
    3. Models to understand dynamic effects and connectedness in transport networks, in particular the dynamics between spatial plans and transport investments.
    4. Indicator calculation methods where indicators are used to audit, monitor or set standards for planning policies (e.g. travel time indicators)
    5. Others?
    An overarching consideration is that we are focussing on information/knowledge to support the planning/policymaking process not on planning/policy measures as such. For example, a policy to locate large traffic generators close to railway stations is not an ‘Accessibility Instrument’. On the other hand, information/knowledge that helps identify what in this context a ‘large traffic generator’ is, or what the level of service of the railway station should be, could be considered an ‘Accessibility Instrument’.”

    • Vesa Kanninen

      November 2, 2011

      Do you se any room for “procedural instruments”, e.g. administrative processes that create accessibility-related procedures (like structured cooperation between transport planning, school authorities and infrastructure services to link information to create school network additions in a way that minimizes travel times for small children, or provides most opportunities for choosing high schools within a city-region)? I admit it’s not in the core of the “instruments”… Naturally, there must be a type 1 and 2 (as listed above) instruments “inside” the process with which data is collected and separate data are combined into accessibility information. However, I feel that often it’s not the method but the process that makes the difference, since the process is the means to get to the data being gathered and the (often ad hoc) method being applied. Thus, I’m inclined to speak about “procedural instruments”. Any thoughts on this?

  4. Avatar of Carey Curtis

    Carey Curtis

    November 4, 2011

    I think when we review this glossary we need to be mindful of its purpose – as I understand it the purpose is so that we can all share a common language/understanding (as far as that is possible!), this is different to neccesarily needing to be academically precise – so for me the glossary as it stands is OK – I wouldn’t get too obsessed with very precise definitions. For me it would be very important to focus on the basics –> so accessibility is the ease of getting to a place/opportunities – so then it is important to distinguish between 1) the accessibility of the transport network and 2) the accessibility of opportunities. Some accessibility tools only do the former.
    I agree with Derek regarding land use planning (sadly it is rarely ethical nor efficient – indeed one of the values of accessibility tools is that they can assist with more efficient land use decisions than has otherwise been the case!) – a definition that would work for me would be ‘a regulatory process by which land uses are allocated in space’

  5. Avatar of Derek Halden

    Derek Halden

    March 8, 2012

    I suggest that the definition “Gravity measures – Defines catchment areas by measuring travel impediment on a continuous scale. ( C. Curtis, J. Scheurer 2010)” is deleted since although the statement is true there are many other accessibility measures that also fit this description and gravity measures do not always relate to catchments. Also the term gravity implies attraction which is correct but could lead to confusion with travel demand planning which relies heavily on gravity concepts. The list of types of measures remains a bit partial and it is beyond the scope of a glossary to do a comprehensive list of all accessibility measures.

    If however some of the most common measures need to be in the glossary then I suggest the three main categories are: 1. based on the utility of travel (e.g. time measures, utility based measures and other transport based value systems), 2. based on the opportunities available from an origin (e.g. Keeble – job opportunities, economic potential measures, Shimbel – nearest opportunities, Hansen origin measures, timespace geographic measures – activity spaces, opportunity surfaces, etc), 3. based on the catchments of destinations (e.g. catchment populations, Hansen destination measures, etc).

    Othewise the list looks good – but as the drafting of the reports takes place and new terms are added they need to be added to the list and modified through debate.

  6. Aud Tennøy

    March 9, 2012

    About ‘planning’ – I find that the present definition from Wikipedia does not really grasp what it means in our context (or what I think it means…).

    Definitions of planning usually include a future-orientation, and a focus on how to achieving something we want or avoid something we do not want. Further, they normally include application of knowledge in order to assess which actions are necessary in order to achieve certain objectives and which should be avoided, as well as consequences of certain actions.

    The aim of planning may hence be defined as to bring knowledge into decision-making in order to improve decision-makers’ abilities to make decisions about future actions which contribute to the achievement of their objectives (see for instance Faludi 1973, Friedmann 1987).

    Byrne (2003:174) discusses planning as “the specification of a proposed future coupled with systematic intervention and/or regulations in order to achieve that future […] a control parameter – something which can have a profound influence on the future which comes to pass”.

    Planning can hence be defined as to apply knowledge in order to define what needs to be done in order to arrive at a desired future situation.
    Aud

  7. Petter Næss

    March 10, 2012

    I have a few comments on two of the proposed definitions:

    Academic rigor/quality. In the text, validity and causal claims and generalizability are referred to as positivist values. However, these criteria are used also by non-positivist, albeit with a different conception of the concepts than those used by positivists. For example, critical realists aim at explanation and identification of causal powers but understand causality in a way very different from positivists. Since the world (apart from artificially constructed natural science experiments) consists of more or less open systems where many causal influences are at work simultaneously but in different configurations, a causal factor does not always produce the same effect, since it may be counteracted, augmented or modified by other causal powers operating at the same time. There is therefore no real-world regularity between cause and effect like the Humean notion of ’each time X, then Y’ embraced by positivist and the principle of ’covering law’. In critical realism, causality is understood in terms of causal powers operating through generative mechanisms, not in terms of regularity between different events. And what can be generalized from an empirical study is how causal powers operate, not the events they produce.
    I therefore strongly recommend that the word ’positivist’ is deleted in the glossary description of academic rigor/quality, since positivism does not have any monopoly on the notions referred to.

    Sustainable accessibility. The definition of this term is somewhat problematic for two reasons. For one thing, it does not include any aspects of social sustainability, only environmental (the latter of course being very important). However, the possibility for vulnerable groups (low-income, disabled, elderly, etc.) to reach facilities for daily activities should perhaps be included in the definition, since non-marginalization of such groups is arguably part of the sustainability concept. Secondly, the formulation concerning environmentally harmful use of resources is somewhat inconsistent. It is formulated as if it were an indicator rather than a definition (‘the amount and diversity of’) divided by (‘the use of resources’). Instead of formulating the definition as such a quasi-quantitative indicator I would recommend to formulate the definition in a purely qualitative way, stating its different dimensions, which dimensions to increase and which ones to minimize.

  8. Karel Schmeidler

    March 12, 2012

    Indicator – The way in which accessibility is expressed. This strongly relates to the concept used
    Indicator should be defined more generaly, there are many indicators used in planning. Accessibility indicator are very special ones.
    The glossary is sufficient for the moment. lets hope it will be more evaluated and improved during the whole project life.

  9. Avatar of Cecilia Silva

    Cecilia Silva

    March 14, 2012

    I agree with several of the previous comments.
    I would like to add the following issues to the discussion:
    1st: I agree that the list looks fine and that we do not need much to have our glossary. We should focus on the key concepts of the Action. Considering this I would actually delete several of the concepts currently in the list because it does not really seam to make sens to discuss them in this forum, such as, academic quality/rigour, accuracy, Interpretability and Quality of data. I know these concepts were put here to clarify doubts during the filling of the Accessibility instrument Survey, but it does not make sense to me to keep them here. I would save this for the explanation of the survey only.
    2nd: I would also exclude the concept “Planning”. First, because, like Aud, I do not agree with the definition, and second because I would not say it is a controversial concept.
    3rd: I would exclude the concept “Concept” and substitute it by a new concept of “Accessibility Measure”. This concept only makes sense when defined and discussed in comparison to “Accessibility instrument” and “Accessibility Indicator” (thus I also suggest “instrument” be substituted by “Accessibility instrument” and “indicator” by “accessibility indicator”) (see definitions below).
    4th: I would also delete the concept of Sustainable Accessibility because, as stated before by others, the concept is context related, and although valid is not sufficiently general to be in this list as a concept for sustainability in accessibility (not all dimensions of sustainability are considered).
    5th: I agree with Derek on the limited definition of gravity measures. I would call this measure “potential measure”.
    6th: I would include Planning Support Systems (PSS) to the list (See definitions below).

    Definitions:
    Accessibility Measure: Theoretical definition of how and what is measured in accessibility, presenting the main objects and objectives of the measure. Examples of accessibility measure: distance measures, contour measures, potential measures, gravity measure. inverse balancing factors, utility-based measures, etc. Each accessibility measure has a general conception and a general formulation of its accessibility indicator.
    Accessibility Indicator: mathematical formulation to measure a certain concept of accessibility (formula plus meaning of each variable or parameter).
    Accessibility Instrument: an operational tool of measure and interpretation of accessibility developed to support planning practice (analysis, design support, evaluation, etc.). May use one or several accessibility indicators. May be of a pure form of one single accessibility measure or combine characteristics of different accessibility measures.
    (I would suggest a scheme to clarify the relationships between these concepts)
    Planning Support Systems (PSS): is a subset of geoinformation-based instruments that incorporate a suite of components (theories, data, information, knowledge, methods, tools, etc) that collectively support all of, or some part of, a unique planning task (Geertman and Stillwell; 2003).

  10. Avatar of Nuno Norte pinto

    Nuno Norte pinto

    March 14, 2012

    I believe that this glossary shouldn’t be a closed matter, as we can still build on these concepts as a result of the Action.
    The final glossary, to be published in the final report (in my opinion), should be some ambitious (but concise) document that could work as a accessibility encyclopedia.

    Proposed changes and new concepts

    Accuracy (of a model) – “it is the extent to which a model is able to capture and simulate a given set of phenomena by producing results that match reference datasets which may include experimental or observed data” (my own definition)

    Interpretability – “The ability of making accessibility measures easy to understand by actors, especially non-experts, regardless of their complexity, by providing readable maps and meaningful indicators of all sorts (normalized values for indicators, monetary values, etc.)”

    Instrument (Accessibility) – “A tool that aims to provide explicit knowledge on accessibility to actors in the planning domain. Mostly, they consist of computer model(s) that transfers data/information about urban systems into meaningful knowledge, by providing visualization tools such as maps or numerical indicators.”

    Planning – “Planning, as a general activity is the making of an orderly sequence of action that will lead to the achievement of a stated goal or goals” (Peter Hall, Urban and Regional Planning, 4th edition)
    This is a much solid definition than the wikipedia’s one.

    Urban Simulation – “use of a wide range of modeling concepts to capture and reproduce any type of physical or socioeconomic phenomena observed in urban systems, allowing the forecast of potential evolutions under controlled conditions to assist planning or decision-making processes in general” (my own definition)

    Usability (of an instrument) – “a qualitative indicator of the extent to which an accessibility instrument is accepted and applied in planning or decision-making processes by its end-users” (my own definition)

About the COST Program

COST is an intergovernmental framework for european Cooperation and Technology, allowing the coordination of nationally-funded research on a European level. More information here.

About the COST Domain TUD

TUD fosters research coordination in the fields of transport and the built environment, which play a strategic role in the modern society and economy. More information here.

About this Action

Accessibility concepts are increasingly acknoledged as fundamental to understand the functioning of cities and urban regions. More information here.