CROW Mapping Positional Accuracy Improvement

Descriptions

Following a statutory process of consultation and appeal, the Countryside Agency (CA) issued in 2004/05 eight conclusive maps of open country (land consisting wholly or predominantly of mountain, moor, heath or down) and registered common land (RCL) in England, which became the basis of the open access rights that the public now enjoys over the mapped areas, subject to the limitations set out by the Countryside and Rights of Way Act 2000 (CROW).      After the publication of the Conclusive Maps in 2004/05, the Ordnance Survey (OS) undertook a 'Positional Accuracy Improvement' programme (PAI) to improve the accuracy of much of its base mapping data. The changes were particularly pronounced in rural and upland areas where much of the CROW mapping layers are present. The PAI update meant that the CA's mapping layers of open country, registered common land and section 15 land no longer aligned with boundary features on OS MasterMap, because the boundary features we 'snapped to' had shifted position slightly. In order to provide a suitable baseline for the review of our CROW mapping data, NE must ensure that the published CROW mapping layers are re-aligned so that they can be accurately displayed against the current OS MasterMap base mapping. It will not be possible to undertake the review without first correcting our existing data. We are asking a geospatial consultancy firm to:    Investigate what existing tools and methodologies are available for undertaking this work.  To make a recommendation to NE about the approach that should be taken.  To provide an estimate of how long it would take to implement across the country.