Depicting: gates, tracks, footpaths and field parcels

Please would you provide the following information pursuant to the Freedom of Information Act:

1. all instructions to surveyors in regard to depicting gates on OS maps from 1900 to 1990

2. policy from 1900 onwards in regard to how to depict on maps the numbering of parcels -  specifically for long thin parcels such as roads, where to print the parcel number

3. all surveys, formal or otherwise, and all surveyors notes, in regard to the area of land covered by County series map Cxxx and Cxxx (outside of xxxxxx) from 1900 onwards

4. policy from 1900 onwards in regard to usage of the terms “footpath” and a “track” and the attributes of a particular way to make it either a footpath or a track.

5.  what is the difference between “surveyed”, “revised” and “re-levelled” for County Series Maps? Specifically does this mean that a full or any physical survey was performed at the time of a revision or a re-levelling, and if so how detailed would such a survey be?

Thank you for your e-mail dated 29^th January 2010. We are pleased to respond and provide information in answer to your questions individually. However, Ordnance Survey does not hold all of the information you have requested, and this is stated where applicable.

1. All instructions to surveyors in regard to depicting gates on OS maps from 1900 to 1990.

Ordnance Survey does not hold the requested information for the entire period in question.  The instructions have been issued as indicated in the following texts according to the associated dates detailed with each statement:

• Gates: Gates will be shown closed as part of the features to which they belong. (Taken from instructions for Detail Survey, Revision and Examination of Large Scale Plan [the Red Book] 1952). 

• Gates: Gates will be shown closed as part of the feature to which they belong.  Open gateways will be treated as if they were gated. (Taken from Surveyor Instructions 1977). 

More generally, it has always been Ordnance Surveys policy to survey and depict gates within land parcel boundary features (hedges, fences, walls etc.) in their closed position (normally as part of the alignment of the feature in which they are situated).

2. Policy from 1900 onwards in regard to how to depict on maps the numbering of parcels -  specifically for long thin parcels such as roads, where to print the parcel number

Ordnance Survey does not hold the requested information for the entire period in question.

However on County Series 1:2,500 scale maps parcels were numbered sequentially within each Parish, with subsequent revisions which amended parcel boundaries resulting in suffixes "a", "b" "c" etc, being added to previous parcel numbers, or new numbers being allocated in sequence.  On occasions, where the level of change required, full renumbering by parish was undertaken.  For open ended "linear" parcels such as roads, if not bounded by a sheet edge, these were segmented using pecked lines to indicate the segmentation and the numbering, within the Parish sequence, was generally located as near to the centre of the area as practicable.

From the advent of National Grid 1:2,500 Plans post 1945, the numbering of parcels was based on a four figure grid reference within each Square Kilometre of mapping, representing the co-ordinates of the centroid of the land parcel.  In settlement areas a single parcel number and area was allocated to the defined settlement. 

Fuller details of these principles are contained in "Ordnance Survey Maps of the United Kingdom - A Description of their Scales, Characteristics etc.“, published in 1910, and for more recent matters in "Ordnance Survey maps - a descriptive manual" by J B Harley; published by HMSO, 1975

3. All surveys, formal or otherwise, and all surveyors notes, in regard to the area of land covered by County series map Cxxx and Cxxx (outside of xxxxxx) from 1900 onwards

Ordnance Survey does not hold this information.  The methods of survey used since 1900, involving a "graphical survey" process in which the surveyor built up the new or revised detail of the map using a master copy of the previous map mean that surveyor’s notes etc are transient and are not retained.  The published map sheets represent the outcomes of the survey activity.  County Series maps of the xxxxxx and xxxxxx areas of xxxxxx may be viewed at Legal Deposit Libraries of which The British Library, Euston, London and the Bodleian Library at Oxford University are the two nearest to xxxxxx and xxxxxx; please see contacts for both below.  Otherwise local public reference libraries and County Record Offices may hold copies.

The British Library

St Pancras
96 Euston Road
London
NW1 2DB

Telephone: 01937 546060 (customer services)

E-mail: customer-services@bl.uk

Bodleian Library

Broad Street

Oxford

OX1 3BG

Telephone: 01865 277000

www.bodley.ox.ac.uk

4. Policy from 1900 onwards in regard to usage of the terms “footpath” and a “track” and the attributes of a particular way to make it either a footpath or a track.

Ordnance Survey does not hold this information for the entire period in question.  From 1952 onward, instructions have been as indicated in the text as follows:

• Tracks or Footpaths: These are defined as ways which do not fall within the categories of roads, or car tracks, but which are clearly marked and permanent i.e. graveled, paved, or defined by stiles, gates or permanent gaps; they must also lead to a place to which the public want to go, e.g. between two roads or groups of houses, to a church, assembly room etc. 

The description ‘track’ is to be applied to all such ways which could be (but not necessarily are) used by vehicles or horse traffic.  The    description ‘footpath’ is to be applied to all such ways which owing to narrowness of the existence of stiles, swing gates and similar obstacles, could normally be traversed only by pedestrians. (Taken from Instructions for Detail Survey, Revision and Examination of Large Scale Plan (the Red Book) 1952).

• Tracks: (a) A track is defined as an unmetalled way which is clearly marked and permanent (although not necessarily all weather) and used by vehicles.  (b) All tracks, including unmetalled drives 40 metres or more in length, will be shown and annotated “Track” (Tk).  (Taken from the Instructions for Detail Survey, Revision and Examination of Large Scale Plan [the Red Book] 1963). 

• Tracks: A track is defined as an unmetalled way which is clearly marked, permanent and used by vehicles.  It follows that a track must be depicted at least 2.5m wide. Tracks need not necessarily be “all-weather”. (Taken from Surveyor Instructions from 1977). 

• Tracks: All public tracks will be shown and annotated “Track” (Tk).  Tracks in private gardens will only be shown and annotated when they are 100 metres or more in length. (Taken from Surveyor Instructions from 1977). 

More generally it is a principle of Ordnance Survey mapping that a track is an unmettalled way for vehicles and a footpath is, according to its location a metalled or unmetalled way for pedestrians.  In both cases there must be visible evidence of the existence of the track or path on the ground at the time of survey or revision for the feature to be included within the mapping.  It has always been Ordnance Survey policy that the representation of a road, track or path on an Ordnance Survey map is no evidence of a right of way on the ground, save where specific symbols are included within 1:25,000 or 1:50,000 scales maps.

5. What is the difference between “surveyed”, “revised” and “re-levelled” for County Series Maps? Specifically does this mean that a full or any physical survey was performed at the time of a revision or a re-levelling, and if so how detailed would such a survey be?

a)    Surveyed - when shown in the marginalia of a printed paper map refers to the initial (first) topographical survey of the area by Ordnance Survey;

b)    Revised - refers to any survey process subsequent to the initial survey, which has updated the topographical content of the mapping;

c)    Re-levelled - refers to a process of re-establishing the heights of the height reference points (Bench Marks) and the Spot Heights depicted within the mapping.

Re-levelling occurred nationally post World War II, following the adoption of Newlyn as the reference Datum for Mean Sea Level in place of Liverpool, and has taken place on occasions subsequently when subsidence or other landscape changes have invalidated the previously published information.  Traditionally levelling has taken place independently of topographic revision since different techniques and equipment are employed. 

The initial survey and subsequent topographic revision surveys will have been conducted to the accuracy standards prevailing at the time of the survey activity.  Accuracies employed prior to and current in 1975 are described in J B Harley's manual referred to above.  Current mapping accuracy standards for large scales mapping may be found at:

http://www.ordnancesurvey.co.uk/oswebsite/products/osmastermap/faqs/topo019.html

More generally Ordnance Survey uses a number of parameters to define accuracy:

• Precision:  the resolution of the geo-reference co-ordinates of individual items contained within the data;
• Geometric fidelity:  the degree to which the geometry of individual features within the data represent the ground alignment and shape of the features being represented;
• Relative accuracy:  the degree to which distances between adjacent or near-adjacent features contained within the data represent the equivalent ground distances, orientations and physical relationships;
• Absolute accuracy:  the degree to which the geo-locations of feature(s) within the data represent their absolute position on the surface of the earth.

Those employed currently within Ordnance Survey, and which are broadly indicative of past specifications are:

Relative accuracy

(Nominally measured over distance in brackets)

Absolute accuracy

Please note that your enquiry has been processed to Freedom of Information guidelines.  As all requested information has been provided, we have determined that in all the circumstances of this case the Public interest consideration (section 17 FOIA) is not applicable in this instance.

If you are unhappy with our response, you may raise an appeal to our Appeals Officer at:

Complaints Team

Customer Service Centre

Ordnance Survey

Romsey Road

SOUTHAMPTON

SO16 4GU 

Please include the reference number below. The Appeals Officer will ensure that the process has been followed correctly, questioning any decisions taken regarding the original response and recommending disclosure of additional information if appropriate.

Thank you for your enquiry.

Reference number: FOI1031/January 2010