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Error rate of 0.18% detected in digital mapping of land

16 Jul 2021 / ireland Print

Error rate of 0.18% detected in digital mapping of land

An error rate of 0.18% was detected after the digitisation of the Property Registration Authority (PRA) map record, Minister of State Peter Burke (Department of Housing, Local Government and Heritage) told the Dáil this week (15 July).

The digital transfer took place between December 2005 and August 2010, and 2.5 million registered land parcels, comprising 15 million line entities, were digitised from 36,000 PRA paper map sheets.

A subsequent comprehensive assessment of the quality of the data capture was carried out, which revealed the error rate. 

The minister said the digital mapping project involved complex factors such as:

  • Moving all registrations from the now defunct County Series and Irish Grid map projections to the latest Irish Transverse Mercator map projection,
  • Development schemes mapped on the PRA paper-based record were found to be at variance with the more accurate “As Built” layout presented by Ordnance Survey Ireland,
  • Transferring registrations from western seaboard counties which, up until the digital mapping project predominantly mapped on 1/10560 or 6” Ordnance Survey mapping, had not benefited from any revisions for decades,
  • Deciphering map data on old PRA paper maps, some of which were 100 years old and,
  • Deciphering map data on badly damaged PRA paper maps.

The minister was responding to a question from Sinn Féin TD Deputy Pádraig Mac Lochlainn (Donegal), who said a number of his constituents across north County Donegal had come into conflict with their neighbouring landowners arising from discrepancies between their original folio Land Registry maps and the digitised version.

The minister responded that the digitisation process had been validated by international mapping and land administration experts.

Robust structures

He said the PRA has “robust structures” whereby the registered owners of properties or their representatives can engage in relation to such matters.

“The PRA also has a longstanding and valued relationship with solicitors, surveyors, engineers and architects in all matters pertaining to property registration,” he added.

“The PRA’s experience has been such that many of the queries received, once investigated, do not indicate any registration error,” the minister continued.

“Many of the perceived errors do not emanate from the PRA but, in fact, can originate from inaccuracies in the application map lodged for registration. It should be noted that the responsibility for the accuracy of the application map lodged rests with the applicant,” he said.

The PRA digital mapping project resolved many thousands of pre-existing issues and anomalies in the paper-based map system, the minister said.


“Being pro-active in the adoption of Ordnance Survey topographical detail, during digitisation, has absolved many property owners of the need to incur costs in an effort to perfect or amend the Land Register to reflect the actual position on the ground,” he said.

Queried registrations will require retrieval of the original documents and maps for analysis and examination.

Irish Land Commission maps and documentation may be consulted to reach a conclusion.

The minister added that approximately 50% of PRA-reviewed cases result in no change to the registration, yet are very time consuming to investigate.

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