A GIS-based Route Mapping Tool for Disabled Access in Urban ...

EnviroInfo 2002 (Wien)Environmental Communication in the Information Society - Proceedings of the 16th ConferenceCopyright © IGU/ISEP, Wien 2002. ISBN: 3-9500036-7-3A GIS-based Route Mapping Tool for DisabledAccess in Urban EnvironmentsLinda Beale 1 , David Briggs 2AbstractAccess and mobility are important dimensions of quality of life. For wheelchair users,everyday trips are often fraught with problems with many barriers, imperceptible to theable-bodied, hindering or totally restricting mobility. The MAGUS project developedand tested a decision-making tool that offers information that will assist route planningbased upon the situated knowledge of wheelchair users. The study employed social sciencetechniques to investigate and quantify urban barriers, and GIS and computer technologiesto translate these into an operational route assessment and modelling package,using dynamic segmentation and network analysis techniques. This tool was applied andtested in Northampton, UK and provides a decision support and mapping tool for planners,and a guidance device to help wheelchair users.1. RationaleQuality of life is strongly modified by issues of access and mobility. For wheelchairusers, everyday trips are often problematic (Centre for the Environment for theHandicapped, 1986a, 1986b; Imrie, 1996). Many barriers, imperceptible to the ablebodied,hinder or totally restrict mobility (Palfreyman, 1991). Some of these problemscan be anticipated or avoided if wheelchair users have good information aboutaccess and mobility options. Acquiring the right information is likely to be a particularproblem, especially when visiting an unfamiliar area.In the long-term urban spaces should be designed so that they are intrinsicallymore accessible and sensitive to disabled people. Those who plan or manage the environmentshould ensure that the barriers that disenable people, such as wheelchairusers, are reduced. Rarely, however, are the views of wheelchair users fully incorporatedinto the urban planning process, nor do planners traditionally possess either theexperience or the mapping products to help them evaluate the effects of planning decisionson access and mobility by disabled people (Imrie & Kumar, 1998). If the1 2 Department of Epidemiology & Public Health, Imperial College of Science & Technology,Norfolk Place, London W2 1PGe-mail: l.beale@ic.ac.uk

162knowledge of those who encounter the problems is not used, then urban places arelikely to remain hostile environments for many people. Indeed it is apparent thatmany of the changes which have taken place in towns and cities in recent years havemade access and mobility more, rather than less, difficult for disabled groups likewheelchair users. Research undertaken by Imrie and Wells (1993) showed a widespreadignorance amongst officers about ‘planning for the disabled’. There is, therefore,a need for information systems and good quality maps that can help plannersassess and compare the effects of planning decisions on disabled access to urbanspaces, and provide a means of integrating the needs of the disabled into urban planningand design.A more immediate strategy to overcome problems of inaccessibility is to improvethe mapped information available to the disabled, in order to enable them to betterplan and control their own use of urban space. At present there is an unevenness ofinformation targeted at disabled people to assist trip-making. Where town guides doexist they often provide little more than lists of services and facilities for disabledgroups in general. Attention is rarely drawn to those facets of urban places that hinderor prevent mobility. Not all towns in the UK have access guides and often wherethese do exist they were compiled some years ago and now need updating. There isno consistency within such guides, in terms of their level of detail, range of topics,style, presentation and format. Typically, most guides only give information on aspectsof access into and within buildings, together with a list services and facilitiestargeted at the disabled, while, there is an absence of information about street environmentsand mobility options. Consequently, people with disabilities are not able tomake informed decisions about how to move around urban places (especially instreets and those public spaces between buildings). The need is for informationwhich is sensitive to the disparate requirements of different user groups, and, ideally,to the individual user. The information provided must be based more firmly on theperceptions and experiences of the disabled themselves and be more readily accessibleto users. Furthermore, it should be possible to be readily updated, so as to incorporatethe often temporary but, nonetheless, severe changes that occur in the urbanlandscape.With traditional paper-based maps and information, these requirements are noteasily met. Through the use of Geographical Information Systems (GIS), however,the possibility exists to provide both planners and disabled individuals with up-todate,detailed and customised information to help them plan and manage their accessto urban areas. Providing this information in an interactive form would greatly enhancethe individual autonomy and quality of life of disabled people.Using GIS it is feasible to capture and integrate the relevant information at a highlevel of spatial resolution, to model either individual routes or access surfaces usingmulti-criteria assessment (MCA) techniques, and to present the results in map form.Network analysis and Artificial Intelligence (AI) techniques also provide the capabilityfor route modelling and route finding along networks. However, to translate thisCopyright © IGU/ISEP, Wien 2002. ISBN: 3-9500036-7-32504 EI P 906 I2 BealeL.doc 29.08.02

163capability to an operational planning and information tool, or a route-finding system,requires a number of problems to be solved. The first of these is to define the factorsthat actually determine access and mobility for disabled people.2. Defining the barriersA Geographical Information System (GIS) has been used to develop, test and apply aroute mapping tool for disabled access in urban areas. This model aimed to provide abasis for a fully interactive system that will allow wheelchair users to assess, compareand select routes through urban areas, which best meet their individual circumstancesand needs. Additionally, it has been developed for use by urban planners tobetter understand urban morphology from the perspective of a wheelchair user - potentiallyleading to recognition of hindrances and improved policy and decisionmaking.It can also be used to help local authorities and disabled groups produce upto-datemaps on access for the disabled to urban areas. The model has been testedand applied in Northampton, UK.In designing the GIS-based model and outlining the project aims, the demands ofthe end users were considered throughout. The GIS-based model was intended foruse by both wheelchair users and urban planners, although clearly the knowledge ofthe subject laid predominately with one user group. In order to improve access to informationpotential a primary aim in model development was to create a simple andstraightforward structure so that the GIS-based model could ultimately be used byboth those experienced and inexperienced with computers.Four hundred wheelchair users were contacted from across Northamptonshire,England, and invited to complete a postal questionnaire to determine their perceptionof hindrance in urban spaces. The sample was designed to be representative of age,gender, level and type of disability and the type of wheelchair used so as not to bebiased towards particular population groups. The questionnaire was organised intofour sections. These covered personal details including disability and type of wheelchairmost commonly used; those aspects of the built environment that constrain mobilityand access; problems faced when attempting to travel to and around Northamptontown centre; and facilities regularly used by wheelchair users and what problems,if any, were routinely encountered. The questionnaire responses provided importantinsights into the real problems that exist for wheelchair users in navigating urbanspaces (Figure 1). A number of focus groups were convened to examine emergentthemes more rigorously. During the course of each session photographs of obstaclesmost readily recalled in the questionnaire were used to stimulate discussion.Copyright © IGU/ISEP, Wien 2002. ISBN: 3-9500036-7-32504 EI P 906 I2 BealeL.doc 29.08.02

164Urban barriersstepshigh kerbsdeep guttersgravel surfaceslack of dropped kerbsnarrow pavementssteep gradientsdifficult camberscobbled surfacescongested pavementsdropped kerbs not adjacentuneven paving slabsraised manhole coversstreet furniturehandrails not on ramps9181767573696665625656504743420 10 20 30 40 50 60 70 80 90% of respondents who found thebarriers either prohibitive or severeFigure 1 Percentage of questionnaire respondents regarding an urban feature to be asevere prohibitive barrier to movement, by type of wheelchairThe results of both the questionnaire and focus groups highlighted the importancenot only between urban features but also in diversity of experience and type ofwheelchair used. As would be expected, there was consensus that steps are a majorimpediment, denying access on most occasions. High kerbs, too, limited movementas do poor surface conditions of various kinds. Where there are no adjacent droppedkerbs then road crossing may be impossible and journeys are lengthened. Gradientsare a particular problem for most manual and assisted wheelchair users but were amuch lesser problem to users of powered wheelchairs. A number of other urban barrierswere identified as being prohibitive to access including narrow pavements, inconsiderateplacement of street furniture, gutters, and difficult cambers.3. Database developmentIn order to construct a database of the identified barriers to wheelchair access for usein the GIS model, it was necessary to devise a number of methods to accuratelyquantify urban features. A number of pavement surface types were identified and therolling resistance of each was calculated. Dragging a wheelchair and occupant overthe surface with a force gauge allowed the required effort to be quantified. Theweight of the occupant increased the required inertia, but rolling resistance was observedto level out and become relatively consistent at distances greater then 8m.Copyright © IGU/ISEP, Wien 2002. ISBN: 3-9500036-7-32504 EI P 906 I2 BealeL.doc 29.08.02

165The starting force was, as would be expected, always the highest recorded force forall surfaces. This measure is weight dependant. It was, however, found to be a veryimportant measure, with uneven surfaces causing the wheelchair to be slowed downand in some cases brought to a halt. The range of measured force was therefore acrucial measure, providing a good indicator for surface roughness. The results reflectedthe questionnaire and focus group responses.Dropped kerbs provide crossing points for wheelchairs across roads and consequentlyhad been identified as being extremely important to allowing movementaround an urban area. A total of nine factors were identified as being required to assessa drop kerb and included: height, surface, slope, camber, width, orientation,curvature, with bullnose and brickrunners. Collation of this information enabled acomprehensive and efficient method of ranking drop kerbs.The remaining urban features to be included in the digital database (e.g. the locationof steps, ramps and cambers) required only mapping by location, rather thanquantifying. Many of the urban features were gathered in the field, using a palmcomputer running ArcPad GIS. This provided an efficient method of mapping thedata and reduced the error that can often occur during data conversion.Initially, a network coverage representing pedestrian routes around the town centrewas derived using Ordnance Survey Land-Line data - an enhanced vector dataset, where features are represented as points and lines that are digitised and specificallycoded to show 37 layers. A number of issues arise when attempting to demarcatepavements as a range of different features defines pavement edges (e.g. buildingoutlines, walls, road edges). In order to provide consistency, pavement centrelineswere manually extracted using the Ordnance Survey Land-Line data as a backdrop.This removed the need to alter the original data whilst allowing the designer to uselocal knowledge to derive a network that best represented the general flow of pedestriansaround the town centre. Using the Dynamic Segmentation module inARC/INFO ® , linear measurements were used to define locations along linear features.All urban barriers were then associated with the correct measurement along theroute, defined as linear measures (e.g. pavement surface) or point events at measuredlocations (e.g. steps). The routes were assigned a direction along which the measurementsare made, thus, each route must be labelled twice since some of the barriersare direction dependent (e.g. slope). The drop kerbs were then stored as turntabledata, thereby allowing the direction of traverse to be significant. Storing the data usingdynamic segmentation means that the data is stored as a tabular database. Datacan be updated without altering the network topology.3. Model developmentMAGUS (Modelling Access with GIS in Urban Systems) is built entirely withinESRI ArcView ® GIS, using AVENUE programming language and Dialog De-Copyright © IGU/ISEP, Wien 2002. ISBN: 3-9500036-7-32504 EI P 906 I2 BealeL.doc 29.08.02

166signer. Selection is made primarily through a ‘main menu’ that is permanently visible,with further navigation through the system being facilitated by pop-up menus.The model was designed to be a menu driven programme to ensure that users do notrequire any knowledge of ArcView ® or GIS and is usable by those with little computingknowledge. All choices are made using well-spaced ‘buttons’ with each displayinga simple textual description of the option and Microsoft ® accessible toolswere enabled so that users with mobility impairments could navigate the model andinteractive maps using the 'mousekeys' if preferred. All the scripts for the interfaceare contained within the project and upon initiating the GIS-based model all the requireddata are loaded into the main view and the legends are set.MAGUS has been programmed to use the functionality offered by network analysisextension within ArcView. This enables the modelling of spatial networks byproviding tools to determine paths through linear network systems. The model assessesthe accessibility of routes around the urban area by calculating the 'impedance'that each urban barrier, found along a route, poses to wheelchair users. Impedance isthe ‘cost’ expressed in terms of barrier weightings, associated with each street routeor turn. The weightings were determined based upon the perceptions of wheelchairusers and direct measurements e.g. rolling resistance. Impedance values are calculated,within the virtual table, based upon user specifications and selected route option.Any feature upon a route that prevents wheelchair access is assigned a negativeimpedance value, thereby prohibiting route determination. Among the criteria thatare used to start up the route planning procedure is 'type of wheelchair'. Three categoriesof wheelchair are recognised: manual self-propelled, manual assisted andpowered. Furthermore, each user is required to provide an assessment of their relativefitness or capacity to travel, employing a weighting scale of 10 (low level of fitness/poorability to travel) to 100 (high level of fitness/good ability to travel). Thisallows the route to take into account users demands whilst ensuring the system not sodetailed as to make it difficult to use for non-wheelchair users. Two possible methodsof route selection have been incorporated so that a user may select either an optimalroute based on a 'from and to destination(s)’, or all wheelchair accessibleroutes from a specified location. A further number of options are available in routeselection. For example, six types of route can be selected including shortest route,route with the best surfaces, slopes

1674. ConclusionsA number of volunteers have assisted in evaluating the model performance, includingboth wheelchair users and planners. Volunteers could successfully navigatethrough the model, including those with little and no computing experience and allstated that having used MAGUS, they would be confident using GIS in the future.Those volunteers with planning experience felt that the model provided valuable datato assist in decision-making, in particular because being able to view the wheelchairroutes clearly showed the differences in the route choices available to wheelchair users.Wheelchair users reported that routes the model selected were wheelchair accessibleroutes and that, therefore, it provided an effective tool for route planning in urbanareas.AcknowledgementsThis research was funded by the EPSRC (Engineering and Physical Science ResearchCouncil) as part of the EQUAL (Extending Quality Life) initiative.The project team is also grateful for the support and assistance from Sandra Bell,Northamptonshire Council for Disabled People and Faisal Hussain, NorthamptonhireCounty Council.BibliographyCentre for the Environment for the Handicapped, (1986a) The external environment and theexperiences of disabled people, Centre for the Environment for Handicapped, London.Centre for the Environment for the Handicapped, (1986b) Pedestrianised Areas, Centre for theEnvironment for Handicapped, London.Imrie, R., (1996) Disability and the City, London, Paul Chapman.Imrie, R.. and Kumar, M., (1998) Focusing on disability and access in the built environment,Disability & Society 13 357-374Imrie, R.F. and Wells, P.E., (1993) Disablism, planning and the built environment, Environmentand Planning C 11 213-231Palfreyman, T., (1991) Access and the space that links buildings, Access by Design 56 13-16Copyright © IGU/ISEP, Wien 2002. ISBN: 3-9500036-7-32504 EI P 906 I2 BealeL.doc 29.08.02