Ordnance Datum
The term ‘Ordnance Datum’ refers to the height of mean sea-level, taken from a reference point at Newlyn in Cornwall. This is basis of the national height system for Britain.
The Newlyn Ordnance Datum was preceded by a Liverpool levelling, started in 1840 using a bench mark on St John's Church. In 1844 the datum was changed to the tidal pole in Victoria Dock, but from 1921, this has been generally superseded by the Newlyn Ordnance Datum.
In some remote islands such as Shetland and the Hebrides, datums are based on a local determination of mean sea level.
Ref https://www.ordnancesurvey.co.uk/gps/legacy-control-information/liverpool-to-newlyn
The term Above Ordnance Datum (AOD) refers to a height above the Ordnance Datum. Measurements are given a + or a – sign to signify which side of Ordnance Datum it falls.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
A change to adoptive architecture.
A must read for all built environment professionals.
A sun, tide, mass or scratch dial.
A brief description of time in the sun.
ICE Trustee Board update June 2022
Given by ICE President Ed McCann.
Artificial intelligence and project management
Two new research reports published by APM.
Association for Project Management membership offer
50% off APM Associate membership for Designing Buildings users.
Building safety, a shifting landscape for professionals
A commentary from the insurance perspective.
In brief with further links.
Walter Segal: self-built architect
A definitive book on a pioneer of green architecture.
Funding for heritage on the high street
Using heritage as a catalyst for reviving historic centres.
Commonwealth Heads of Government Meeting update.
Declaration prioritising sustainable urbanisation adopted.
A small hidden, often distant but key building component.
Some brief words about the actuator.
CIAT Chief Executive steps down.
After 34 years at the Institute.
Volunteer opportunity launched by the ICE
To support the next generation of engineers.
Provisional findings show illegal cartels in the industry.
CIAT reporting from the Competition and Markets Authority.
Making sustainable construction number one priority.
The future of construction report.
Interview with ECA CEO.
Many provisions came into force on June 28, 2022.
With room to expand.
An information packed session at the BSRIA conference.
Refurbishment, Energy Efficiency, Indoor air and process.
Create a profile, write informed product articles and share.
Aluminium Composite Panels (ACP) is one example.
We are indeed now 10 years old, so go on and be bold !
Write about something you know, help us build and grow !