Geographic Information System
From GPG
Contents |
What is GIS?
Geographic Information System, usually abbreviated to GIS, is a term '... normally used to describe computer facilities, which are used to handle data referenced to the spatial domain, with the capability to inter-relate datasets, to carry out functions to assist in their analysis and the presentation of the results ...' Chorley Report, 1987.
Geographic information is that which expresses the location and distribution of physical and human landscape features. Those features are widely varied so tend to be grouped into 'themes' such as rivers, roads, vegetation, buildings. The 'system' is the storage of the data in a certain way, usually in a database, or at least in tables. The data is spatially referenced, that is, it has a location, which means it can then be shown on a map. Computers enable the storage and manipulation of the increasing volumes of data and the integration of data of different scales, projections and formats.
Linking list data to a map to make a visual tool is a strength of GIS. The list data becomes the 'attribute' data of the map 'object', the object being a symbol, line or polygon. The results of analysis of attributes can be depicted in many ways, eg. graphical representation of populations within regions.
GIS can also be combined. One set of data alone may be interesting but of little significance: it is the combination of datasets that lead to the true power of the system. For example, to show rights of way alone may be useful but is limited: combining the rights of way with other 'themes' such as land use, conservation data (SSSIs, protected nest sites) development zones, flood risk etc adds value to an analysis by providing new information that would not be detectable otherwise.
Uses of GIS in access management may include:
- identify structures and their attributes, eg. bridges, gates, stiles, signs;
- select and show features with common attributes by single or multiple queries, eg. all footpaths in a district, all headland bridleways;
- to create a 'buffer' of prescribed extent around features, eg. twenty metres from rights of way to depict likely disturbance to ground-nesting birds;
- overlay information, eg. rights of way, SPAs, public transport, information points, car parks, extent of disease outbreak;
- calculate lengths, eg. total length of byway;
- merge multiple layers into one layer, eg. all orders;
- digital terrain modelling from elevations, enabling analysis of cross-slopes and gradients, combined with rights of way data can give gradient profile.
- land use
It is crucial to remember that no matter what the power and potential of the GIS, the output is only as accurate as the input, and as with all databases, the scope, consistency and accuracy of data is critical to the value of the dataset. Security, integrity and protection to ensure its accessibility into the future must also be incorporated into the management of the data.
Why use GIS?
Perform existing tasks more efficiently
A GIS replaces paper maps and documents which have traditionally been duplicated throughout an organisation and which require frequent updating and replacing. Significant cost benefits are achieved by removing the need for paper documents through GIS.
Dissemination and Integrity of Data
It provides all the advantages of controlled information management such as sharing data between multiple users, reducing data duplication and increasing security, accuracy, integrity and validity of data. Shared access to one source removes the inconsistencies and errors that can develop from duplicates.
New Tasks
A GIS provides the technology to perform tasks not previously possible. Multiple map overlays, generation of buffer corridors, surface interpolation and visualisation of terrain models are examples of sophisticated analysis.
New Data and Data Management
A GIS provides the potential to create new information from existing data, through selection and combination analysis techniques. It is based on the assumption that information is a valuable resource to be utilised to its full potential. GIS provide very effective data management, retrieval and analysis tools, but most importantly the capability to depict spatial features and relationships. The location and characteristics of objects as well as their relationships are important in effective management.
Increasingly it is becoming a statutory requirement for organisations to provide accurate and up to date information for a wide variety of purposes, thus the demand for GIS and other automated data handling systems is likely to increase.
Uses of GIS in Rights of Way and Access Management
There are many uses of GIS in access that come to mind immediately and as a GIS is maintained and developed, more uses will be found. The following are some of the most obvious, not necessarily in order of importance.
Definitive Map
A first step for GIS is likely to be digitisation of rights of way. A consolidated digital map can be created, published and maintained using GIS. This basic information has a considerable added value in combination with the following datasets:
Public Path and Modification Orders
It is recommended that the effect of path orders be recorded as part of the consolidation process to generate an omnibus legal event order. Extending the record by including past modification orders and current or potential orders of all types adds to the value of the database by making the information easily accessible to other users (eg. planners, land charge searchers).
Structures and Maintenance Management
Bridges, signs and surfaces that are the responsibility of the authority to maintain will create a database that provides a clear picture of locations and types of feature. Attributes can be used to depict whether maintenance is outstanding or desirable, assisting efficiency, eg. if a visit is planned to a bridge, it can be seen that the sign en route to it needs replacing or that there is an outstanding visit required to an adjacent property holder, or to plan cutting regimes based on frequency of cut required.
The dataset can be expanded to include all structures, including maintenance record and ownership.
Analysis of this dataset can be invaluable in identifying 'pockets' of high maintenance requirement or an area where it could be helpful to seek committed volunteer help. Records of arable paths can be useful in proactively seeking compliance with ploughing and cropping requirements
S147 Authorisations
Locations of structures authorised under Highways Act 1980 section 147 can be helpful for maintenance and enforcement purposes, especially if contracting out work.
Closures, Faults, Problems
Records of temporary closures, identified or reported obstructions and other problems can be of value especially in making the data available to many parties or in publicising closures on the web.
Promoted Routes
Marking promoted routes gives an obvious picture of where further promotion may be desirable to create links or to show lack of routes in certain areas.
Accessibility and Digital Terrain Modelling
Descriptions of furniture, surfaces and gradients or cross-slopes can provide information on the accessibility of any route to any user.
Permissive and Purchased Access
Records of permissive access, whether given freely or contrived through grant or payment schemes helps complete the picture of access to identify deficiencies.
S31 Submissions
Boundaries of land subject to Highways Act 1980 section 31(6) submissions has benefit in the immediate accessibility of both landownership data and constraints to potential modification orders.
Surveys, GPS
GIS can be mobile - there are many resources now that enable a GIS to be used in the field on hand-held computers for both data-capture and survey purposes. Integrating the GIS with global positioning enables locations to be accurately plotted or found. Accuracy varies by area and limitations of equipment but is an invaluable tool (though it may show up serious faults in the definitive map!). It can be used both to follow the line of the map, perhaps to mark an undefined path over open ground, or to plot the walked line for later use, such as for a path to be created.
Aerial Photos and 'Historical' Mapping
Aerial photographs and past Ordnance Survey data can be georeferenced, or are digitally available. They can be invaluable in combined datasets, particularly for definitive mapping or for archaeological constraints.
Landownership and Contacts
It is received information that local authorities know who owns every scrap of land - if only it were true many will say! A dataset can be compiled from various sources and then maintained and extended.
Volunteer Areas and 'Adopted' Paths
Areas of volunteer work forces or adopted paths can show their value (or lack thereof) in combination with maintenance records, perhaps helping to identify where more volunteers would be of use.
Analysis for Performance Monitoring and Funding Bids
Funding bids are largely based on statistics and a great strength of any GIS is its capacity to form statistics for monitoring or analysis. GIS lends itself to this function because of the potential for combining datasets as required depending on the source of funding, such as with public transport or conservation interest or accessibility.
Other Uses
A number of authorities use GIS to provide online maps helping the public find places to walk or ride. Increasingly the definitive map or a working copy is available online and there is potential for links to other datasets such as s31(6) submissions, Schedule 14 applications and public path order applications.
Hampshire County Council created an overlay on its GIS to record all the network improvement suggestions received during the ROWIP consultation. This overlay is available to anyone within the council enabling anyone to easily identify where improvements are required, and ensure they are considered during any negotiations, for example during planning applications, or negotiation over new access through higher level stewardship.
The North York Moors National Park Authority's GIS contains many datasets, including archaeology, grant schemes, conservation areas, sites at risk and planning applications as well as public rights of way data that includes definitive map anomalies, all order applications, unclassified roads, definitive map data and all path furniture. Access to all data by any officer facilitates awareness of constraints and potential for gain through various means.
