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SectionC.11
SectionC.11

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[{TableOfContents title='C.11 Consultations and planning casework'}]
[{TableOfContents title=' C.11 Using GIS in an HER '}]
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!!!C.11 Consultations and planning casework
One of the primary roles of local-authority archaeological and historic buildings services is to provide advice on the implications of development and land-use change to local planning authorities and to other organisations and individuals. For many services, planning applications form the largest element of their conservation workload. However, consultations also include those relating to tree planting, hedgerow removal, agri-environmental schemes and the activities of statutory undertakers.
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!!!C.11 Using GIS in an HER
!!C.11.1 Uses of GIS and spatial data
GIS is now widely used by HERs. Seeing HER data in a spatial context which can be interactively queried and edited has proved very useful. Advantages include:
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Given the importance of this advisory service, and its relevance to monuments, the built heritage and to areas of land, it is important that details are accurately recorded and linked to the HER databases.
*__Visualisation of data as spatial distributions (in either two or three dimensions)__: even a simple distribution (for example Iron Age settlements in Derbyshire) can provide a powerful aid to understanding or providing new insights into data. The ability to view a combination of datasets enhances this potential considerably (for example Neolithic settlements in relation to water courses, soils and contours).
*__Analysing spatial relationships between data__: for example finding all records of upstanding earthworks which lie on arable land. This enables interaction with data and helps to answer research questions (such as were the location of Bronze Age settlements influenced by proximity to, for example, natural resources, soils and water) .
*__Improved decision-making__: for example facilities to help identify sites that may be affected by a planning proposal by using 'buffer zones' - zones of fixed distance around a selected feature generated by the GIS.
*__Overcoming the limitations of paper maps__: for example editing, availability, currency, fragility, distortion, storage.
*__Data integration__: if a database is georeferenced, then a number of separate databases can be brought together in a common environment and viewed together.
*__Improving data quality__: through capturing geographic references directly; automating transfer of information (for example between GIS and text database); routines that check data integrity (for example point in polygon analysis to determine whether a grid reference falls within its assigned administrative boundaries).
*__Saving time__: through rapid availability of a wide range of sources of information. This is particularly true where wider institutional systems are available enabling access to non-archeological data sources as well as conventional HER data.
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!!C.11.1 The archaeological conservation process
The process of archaeological conservation in relation to land-use proposals is a clear, established system, based upon the procedures used in other areas of environmental management.
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[{Image src='fig42.jpg' alt='Figure 19: A GIS generated map showing Bronze Age barrows over Landscape Types and rivers in Hampshire.'}]
''Figure 19: A GIS generated map showing Bronze Age barrows over Landscape Types and rivers in Hampshire (© Hampshire County Council 2007 and © Crown Copyright. All rights reserved. 100019181. 2007).''
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!!C.11.2 Linking GIS to text databases
The databases used for the HER may allow the HER and GIS to be dynamically linked, or the HER may be run with a separate GIS which is updated separately to the HER.
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The key elements of the conservation process can be summarised as:
*__Appraisal__: this first stage involves the conservation archaeologist considering an application or enquiry and using the HER and any other readily available information to provide a professional judgement as to the impact of the proposal on the historic environment.
*__Assessment__: if an impact is likely to occur, and there is insufficient data in the HER to make an informed judgement, then the conservation archaeologist will make a recommendation. This may be that the applicant or organisation be asked to provide the result of a professional archaeological assessment involving a desk-based assessment, field evaluation or building assessment.
*__Mitigation__: on the basis of the assessment phase, an appropriate conservation recommendation can be made in order to mitigate any adverse impacts that may result from a proposal.
Most HERs using GIS will also hold spatial data and other information in the HER databases described elsewhere in this guidance. An important consideration in setting up the GIS will be how to create a link to the HER database. The first step in this process might be to export data from the HER database and use it to create points in the GIS (see [B.10.4|http://archaeologydataservice.ac.uk/ifp/Wiki.jsp?page=SectionB.10#section-SectionB.10-B.10.4DataMigration]). However, this layer will become out of date as new records are added to the HER. HER managers will also wish to use the GIS to check and correct the locations of existing records in the HER database.
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In practice, archaeological conservation is rarely straightforward and is often complicated by the policies, attitudes and resources of other organisations involved in the process. Any record system must be flexible enough to accommodate variability whilst avoiding excessive detail (making maintenance unrealistic for a busy archaeological service). Additional detailed information will remain within the casework files, linked to any computer system.
Various approaches to the problem of keeping the two systems in step can be adopted:
*If the GIS is implemented as a separate system from the HER database then it may be periodically 'refreshed' with new data from the HER database. Any corrections that are made to site locations in the GIS will need to be exported (or manually copied) back to the text database.
*A dynamic link may be created between the HER database and the GIS using a communications protocol to enable grid co-ordinates and other information to be exchanged between the two systems.
*An approach that is not recommended for HERs would be to migrate all the existing HER data into the GIS and to scrap the existing text database. This is because few GIS products support complex data structures directly or offer the same flexibility in indexing or retrieval of information that is recommended for HER text databases.
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!!C.11.2 The historic buildings conservation process
The process of historic buildings conservation in relation to planning proposals is similar to that for archaeological conservation. Until recently, HERs and Historic Buildings Records were maintained in separate local government departments. HERs include historic buildings and some services and are now bringing together advice for archaeology and historic buildings. However, this is a new and developing area for many and it is difficult to offer guidance at this stage. Accordingly, this topic will be expanded in future editions of this manual.
Windows-based desktop GIS systems can be linked to external text databases using one of the following protocols: OLE (Object Linking and Embedding), DDE (Dynamic Data Exchange) or ODBC (Open Database Connectivity):
*__OLE__ is a protocol and set of function calls that are incorporated into the Windows operating system. It allows programs to communicate with each other and is used extensively by Microsoft® to enable word processor, presentation, spreadsheet, database and other applications such as GIS to work together efficiently and exchange data. OLE is used to link or embed objects creating a compound document which can contain other documents: for example an Access form might contain a Word document, an Excel spreadsheet or a Maplnfo workspace. Linking means that data is presented in the compound document but it is retrieved from its original file using the file name. Embedding means that data from the original file is incorporated into the compound document.
*__DDE__ is another protocol that is incorporated into the Windows operating system which allows one application to exchange data or to trigger an action in another application. DDE is a protocol for manipulating applications programmatically and allows data to be extracted, macros or programs to be run or information to be listed. There is some overlap in functionality with OLE but DDE is older, less robust and a more basic method of enabling communications between different applications. DDE is used for programs that do not support OLE, for example to create links between databases and ArcView GIS. DDE is also used for controlling programs across a network (a function not currently supported by OLE).
*__ODBC__ is a common language definition and a set of protocols that allows a database application held on a client machine to interact with a different database application held on a server across a network. For example, using ODBC, an Access database held on a work station can query and exchange data with an Oracle database on a network server. For this to happen, ODBC drivers that are appropriate for the application software need to be installed on both the client machine and the server machine.
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!!C.11.3 Why record conservation advice?
There are several reasons for recording the conservation process on a database:
*__Consistency__: it is important to ensure that responses to consultations are consistent with, or at least taken in the context of, previous advice.
*__Monitoring__: as casework progresses through the conservation cycle, it needs to be tracked. Often projects can last several years and the database should contain sufficient information to enable an archaeological officer to understand the current status of any particular project.
*__Statistics__: local clients/partners and organisations involved in national research often request statistics about conservation advice and the HER should be able to produce this in a variety of forms.
*__Searching__: the database can act as an index to the more detailed casework files held elsewhere in hard copy format.
!!C.11.3 Developing HER layers in the GIS
The way information has been modelled in the HER text databases will have a significant influence on the way the spatial information is constructed. The current data model may be based on MIDAS ([Lee 1998|Bibliography#Lee 1998|target='_blank']) or derived from earlier monument-focused systems. Different attributes or data fields from the text database will be referenced in the GIS and used to create different layers or themes. A problem that will need to be accounted for is that data may not be entirely consistently recorded throughout the database: for example a monument-focused database may have contained some information about events and the HER may be in the process of implementing the event-monument-source data model. In developing HER layers in the GIS the following will need to be considered:
*the initial data load from HER text database to GIS (see [B.10.4|http://archaeologydataservice.ac.uk/ifp/Wiki.jsp?page=SectionB.10#section-SectionB.10-B.10.4DataMigration])
* subsequent updates of the GIS layer (that is, with new records entered into the text database)
*subsequent updates of the text database (that is, with updates to grid references or new records imported from the GIS).
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ALGAO:UK, which represents the majority of local-authority archaeological services in England, Wales, Scotland, Northern Ireland, and the Isle of Man has begun the process of undertaking annual surveys of its membership to gather information on conservation casework. This will enable the identification of national trends and gauge the effectiveness of policy and legislation relating to the historic environment.
The ideal 'relationship' between text database and GIS is one in which data can be entered either through the GIS or through the text database, but this requires a close connection between the two systems. This is generally provided by a computer-generated record number (such as the HER number for monument records) which is used to link information held in data tables in the two systems. The HER text database will normally control the allocation of unique identifiers for monuments, events, sources and consultations. Users would go to the HER text database to create a new record and then, using an OLE or DDE link, go into the GIS to add or modify spatial data. With this type of link, core record details are copied from the text database into the GIS and spatial references are copied back from the GIS into the text database.
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!!C.11.4 Consultation record and recommendations
Any information system needs to be sufficiently flexible to be able to reflect the complexities and iterative nature of the consultation process. The details of incoming consultations should be recorded as well as the details of outgoing advice. It should be possible to record not just the initial response to a consultation (for example a desk based assessment), but also any subsequent recommendations (for example a field evaluation or mitigation recording). To complete the picture, the recommendation should be linked to any resulting event(s) (see Figure 22).
An even higher degree of integration between GIS and text database would allow users to start by creating a new record in the GIS. To achieve this the GIS needs to be able to activate the text database to generate the next unique identifier in the sequence.
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%%image-caption
[{Image src='fig22.gif' alt='Figure 22: Consultation and conservation advice.'}]
''Figure 22: Consultation and conservation advice.''
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When configuring the link between the GIS and the text database, users also need to consider what information will be passed between the two systems and specify appropriate rules for updating. Useful information to pass back from the GIS will include grid references, administrative boundaries and environmental features such as soils and geology. Useful information to pass from the text database will include monument type, period and building materials.
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!Consultation data
A typical consultation record for a planning application from the North Yorkshire County Council HER which uses exeGesIS SDM Ltd’s HBSMR software, version 3.04 is shown in Figures 23 and 24. Other types of consultation, such as countryside management works, are each recorded slightly differently depending on how we use the data for statistical and other purposes.
HER users also need to consider what information they wish to generate 'on the fly' in the GIS and what they wish to record directly in their text database. For example, a corporate GIS system may contain a large number of boundaries such as National Parks, Areas of Outstanding Natural Beauty (AONBs) and SSSIs Visual inspection of the GIS or a spatial query can readily identify which monuments lie within any of these boundaries without the information being directly attached to the monument records in the text database. HER managers are thus able to differentiate between important information about the monument status that they wish to appear on screen and in reports (for example scheduled status) and spatial queries that can be built up according to need in the GIS.
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!!C.11.4 Mapping features on the GIS
Mapped features representing the 'real world' are abstractions and symbols are used that can be readily understood or related to a key. For example, at a scale of 1:1 million, a city may be represented as a point - a completely abstract representation but one which is understandable and appropriate to the scale of mapping. Larger-scale maps generally use less abstract symbols, so for example at 1:10,000 the same city will be represented by the outlines of buildings, roads, gardens and so forth.
In GIS, features can be represented using points, lines, polygons and 'poly-lines' (a continuous line consisting of multiple lines joined together). All of these have their uses in representing archaeological and historic features. For example, points could be used to represent find spots and also perhaps to indicate the location of features where these are already shown on the map, for example points within building outlines. Points are also useful for showing site locations in distribution maps at scales where polygons and polylines simply would not be visible. Lines can be used to indicate linear features such as roads, canals and railways.
In deciding which shape to use, it is important to consider to what purpose the data will be put. If, as in many cases it will be, the aim is to indicate the extent of a monument or building, then polygons will be most useful. If the purpose is to show discrete find spots then points are more appropriate. The next issue is how and where these shapes are to be drawn and the accuracy that is required; the scale of the mapping available will affect the decision.
It is difficult to give detailed guidelines but the issues discussed below are worth taking into consideration.
!Depiction of the extent of known boundaries
Where the extent of the monument is known and especially where the monument or building is clearly visible, then there are advantages in showing the extent of the monument on the GIS. This enables users to see the monument or building in relation to other features in its landscape setting. Figure 20 shows an example of.the use of polygons to plot the early 19th century defences south of Chelmsford in relation to contours, thus allowing their topographical location to be understood.
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[{Image src='fig23.jpg' alt='Figure 23: A typical consultation record from the North Yorkshire County Council HER showing the details tab.'}]
''Figure 23: A typical consultation record from the North Yorkshire County Council HER showing the details tab (North Yorkshire County Council and exeGeSIS SDM Ltd 2007).''
[{Image src='fig44.gif' alt='Figure 20: A GIS layer showing the use of polygons to show the extent of the early 19th-century defences at Chelmsford.'}]
''Figure 20: A GIS layer showing the use of polygons to show the extent of the early 19th-century defences at Chelmsford. (© Essex County Council 2007and © Crown Copyright, All rights reserved. 100019602. 2007).''
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The Details tab records the baseline information about the consultation, in this example, a full planning application.
*__Organisation and Contact__ record the Local Planning Authority and planning officer
*__Applicant and Agent__ are self-explanatory
*__External reference number__: this is used to record the unique external reference number allocated by the consulting body (such as the planning application number) or by the conservation archaeologist where no other acceptable reference is available.
*__Case Officer__ records the curatorial archaeologist dealing with the consultation
*__Log Date__ records the date the planing application appeared on the weekly list
*__Target Date__ records the date the consultation response is required by
*__Consultation__: this is used to record the nature of the consultation, for example what type of planning application, whether it is a pre-application enquiry from a developer or a countryside management scheme. The terms that can be used in North Yorkshire are controlled by a look-up table based upon a locally-adapted version of the ALGAO Consultation Type wordlist ([http://www.jiscmail.ac.uk/files/FISH/ALGAOConsType_1.html|http://www.jiscmail.ac.uk/files/FISH/ALGAOConsType_1.html]).
*__Development Type__ records the general nature of the development or land-use change proposal. The terms that can be used in North Yorkshire are controlled by a look-up table based upon a locally-adapted version of the ALGAO Work Proposed wordlist ([http://www.jiscmail.ac.uk/files/FISH/ALGAOWorkProposed_1.html|http://www.jiscmail.ac.uk/files/FISH/ALGAOWorkProposed_1.html]).
*__Site name__: it may be useful to record a site name or plot number, especially if different to the location, as many developments have distinctive names which are not part of the subsequent address.
*__Parish records the civil parish in which the proposal is located. In North Yorkshire each parish has a four-figure code, the initial number of which identifes which of each of the seven districts it is part of.
*__Location__: this records the address of the site in question or the broad area under consideration.
*__Proposal__ records in more detail than Development Type the nature of the consultation proposal
!Conventions for depicting uncertain boundaries
Where the extent is uncertain, then, as is often done with more conventional mapping, the boundary could be drawn using the nearest modern boundaries that enclose the known features (metadata should be recorded explaining why the polygon has been drawn in this way).
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!Recommendation data
The Consultation Stages tab is used to record the advice given and subsequent stages relating to that consultation, as well as the dates these occurred.
Uncertainty can also be represented by symbols. For example, solid lines might be used to represent known boundaries, while uncertain boundaries could be represented by broken (dotted) lines. Some GIS may allow 'mixed' symbols within a polygon (for example where only one boundary is uncertain), though in most, a separate line would need to be digitised over that part of the polygon.
!Creating a GIS layer to show legally defined boundaries
Many sites recorded in HERs require special consideration in land-use planning, for example sites that are afforded statutory protection, which may have a legally defined boundary showing the protected area (Figure 21). The protected area may differ from the full extent of the monument site, such as a monument site that survives partially as earthworks and partially as cropmarks, with the better preserved portion of the site being scheduled. For these reasons, it is recommended practice to create separate layers within the GIS depicting the extents of protected sites, for example a Scheduled Monument (SM) layer would be created for scheduled monuments. These can then be displayed over other polygons that might show features or monuments both lying within and outside the protected area. It is recommended that HERs should, where possible, obtain digital boundaries from the organisation responsible for maintaining them, for example scheduled monuments from English Heritage. It has been recently agreed in Scotland that the RCAHMS displays site polygons as known extents, while the HERs/SMRs display site polygons with buffer zones. The extent of those buffer zones and so forth are still being discussed but agreement should be reached by end of 2006.
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[{Image src='fig24.jpg' alt='Figure 24: A typical consultation record from the North Yorkshire County Council HER showing the Consultation Stages tab and the link to the related event record.'}]
''Figure 24: A typical consultation record from the North Yorkshire County Council HER showing the Consultation Stages tab and the link to the related event record (North Yorkshire County Council and exeGeSIS SDM Ltd 2007).''
[{Image src='fig45.gif' alt='Figure 21: Great Chesterford scheduled area.'}]
''Figure 21: Great Chesterford scheduled area (© Essex County Council 2007 and © Crown Copyright, All rights reserved. 100019602. 2007).''
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__Stage__ In North Yorkshire, this has been simplified and all are classed as ‘curatorial work’.
!Scale of mapping against which data is captured or displayed
It is important to be aware of the implications of the scale of mapping against which heritage objects are captured or displayed. Map making is a process of reducing complexity and maps are drawn in a way that emphasises important features while suppressing unimportant ones. This is the 'selection and simplified representation of detail appropriate to the scale and/or the purpose of a map' ([ICA 1973|Bibliography#ICA 1973|target='_blank']). Thus, if the width of a road on a 1:1,000,000 map were to be accurately measured, its representation would be considerably wider than the a real-world width of the road. As roads are important features on maps they need to be emphasised and, as a result, on the map any adjacent features are shifted.
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__Action__ In this example of the North Yorkshire planning application, each of the stages visible in Figure 24 record when the consultation was sent by the LPA, the advice given and when (in this instance, for evaluation by trial trenching), the preparation of a WSI and the date, and the receipt of the evaluation report, and date. A further four stages that are not visible in Figure 24 document the subsequent advising of a watching brief, the preparation of a WSI for this, the receipt of the report and the advising of compliance with the archaeological condition. The terms used are controlled by a look-up table.
Because successively smaller scales of mapping are more generalised, an object whose position was captured against a small-scale map will, when displayed against a larger scale of map, appear to be in the wrong place (and vice versa). For example, the outline of a building captured against a 1:10,000 OS raster map will not be reliably displayed against 1:1,250 OS Landline because the digitised boundaries will not match the Landline boundaries. This effect is most marked when digitising from very small-scale mapping. For example, if Roman roads were digitised from a 1:1,000,000 map base, when displayed against a 1:10,000 map base, they might be up to 1 km away from their expected position. Thus, a dataset captured at small-scale is unsuitable for display against a detailed large-scale map.
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__Stage Start and Completion Dates (see Figure 24 ) for__:
*Stage 1: records when the application was requested and received respectively (in this example the application was sent to us automatically, so only an end date is recorded). This allows us to distinguish between those planning applications that we request and those that come to us direct, and also to record the length of time between request and receipt.
*Stage 2: Start date is when the application was received. Completion Date is when the advice was given/sent. This stage allows us to prepare statistical information for our local performance indicator based up the length of time taken to respond to planning application consultations.
*Stage 3: Only Completion Date is filled in to record when a WSI was prepared. This stage can also be used to record ‘WSI Agreed’ if a WSI is sent to us for comment and agreement. In this instance Stage Start date can be completed to record when the document was received.
*Stage 4: records when a report has been received in the Completion Date. This data is also recorded in the corresponding Source record for the report.
!Capturing archaeological and architectural boundaries
As a general guide, 1:10,000 is the smallest scale of mapping against which the boundaries of archaeological monuments or features should be captured. For the outlines of detailed features, such as buildings, larger scale mapping such as 1:2,500 or 1:1,250 is preferable. Smaller scale mapping (for example 1:25,000 or 1:50,000) may be useful for capturing general area information (such as the bounding extent of a large field-walking survey).
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__Overall Outcome__ records the final outcome of the Local Planning Authority’s decision on the planning application. The terms that can be used in North Yorkshire are controlled by a look-up table based upon the ALGAO Final Outcome wordlist ([http://www.jiscmail.ac.uk/files/FISH/ALGAOFinalOutcomeLUT_1.htm|http://www.jiscmail.ac.uk/files/FISH/ALGAOFinalOutcomeLUT_1.htm])
In each case, it is essential that the scale chosen is related to the purpose to which the information will be put. Details of the scale of map used in data capture should be documented in metadata.
!Accuracy of grid references for archaeological point data
In archaeology it is common practice to record the location of features using six or eight-figure grid references, for example TQ 367425. This convention presents real problems when translated into GIS because these co-ordinates represent the bottom left-hand (or south-west) corner of a square. A six-figure grid reference actually represents a 100 metre square, while an eight-figure grid reference represents a 10 metre square. The actual location of the archaeological feature lies somewhere within the square, at an imprecisely defined and perhaps uncertain point.
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__Date Completed__ is used in North Yorkshire to record when the intial consultation response was made (in this instance the same date as for the Completion Date of Stage 2).
If locations expressed as grid references are exported directly into a GIS and displayed as point data, the maps produced can be misleading. This is because the process of exporting the data can displace knowledge about the precision with which the grid references have been recorded.
For this reason 'padding' grid references with zeros added to the end of the numbers is a practice that can rarely be justified because, without supporting data, the process of exporting grid references from a text database into GIS can make it impossible to reconstruct whether the location of a find was generalised to the nearest major grid line, or fortuitously aligned with it.
HER managers can avoid the loss of this important information if the following measures are taken:
*ensuring that the HER text databases generally contain information relating to the site location, and recording both how the grid reference was derived and its precision. Points can be created in the HER's GIS based on grid references exported from monument records in HER text databases while retaining a link between the two systems. Data relating to the accuracy of the grid reference can be exported to the GIS alongside the grid references and used to select an appropriate symbol to depict the point.
*ensuring that metadata relating to the accuracy of the source of the locational information is recorded. If a site location is given to six or eight figures in a source but is depicted as a point accurate to 1m in the GIS, then the level of precision must be recorded in metadata.
!!C.11.5 A sample heritage GIS
GIS systems are made up of 'layers' of information, which can be overlaid, combined and analysed to create new information. For example, the location of a number of archaeological sites could be compared to the location of aspects of the environment (Figure 22).
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[{Image src='fig46.jpg' alt='Figure 22: Examples of layers in a GIS.'}]
''Figure 22: Examples of layers in a GIS.''
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These can then be used to identify sites which lie within the boundaries of particular soil types, creating new information (very useful, for example, in identifying impacts of agri-environmental schemes, set-aside, and so forth) (Figure 23).
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[{Image src='fig47.jpg' alt='Figure 23: A new GIS layer: archaeological sites on arable land.'}]
''Figure 23: A new GIS layer: archaeological sites on arable land.''
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