Surveys: When is North not really North?
One of the most common causes of confusion for clients dealing with property is the different north points shown on plans. What many people don’t realise is that there are several different forms of “North”, depending on where the term is used, and there can be quite substantial differences between them.
For example, there is:
This is the North you will see used on the majority of property titles, and reflects the direction calculated by the last surveyor to register a plan for the site. In terms of a land survey, this is a general approximation of true north, so Land Use Victoria and the Surveyor Generals Office require all licensed surveyors to use the term “approximate true north”.
Forgive us, but MGA North (often referred to as Grid North) requires a fairly technical definition. It is derived from the Geodetic Datum of Australia, (currently referred to as GDA2020) and is the north specified by the Australian Government for mapping.
To confuse things even more, MGA North shifts slightly with the movement of tectonic plates and the governments preferred reference plane! Current legislation requires us to work to MGA2020, but previously the standard was MGA94, and prior to that AMG.
Depending on where you are in Victoria the difference between Title North and MGA North can be anywhere between 1 and 10 degrees
This is calculated according to the Earth’s axis and is the direction along the surface of the planet towards the geographic North Pole, so it is affected by earth’s rotation. For a surveyor to calculate True North, they must first determine MGA North then allow for the relevant declination. Depending on where you are in the state, the declination from MGA North to True North will be between 1 and 2 degrees.
This is the direction that the north end of a compass will point based on the Earth’s magnetic field at the point you are standing at the time. Many people are surprised that magnetic north can vary by as much as 15 degrees at different points around the globe, so if you are using a compass you need to allow for the magnetic variation to establish where north really lies.
It is also important to remember that the magnetic north pole moves over time. In the past the official location of the magnetic north pole was updated every five years. However, the pole has recently begun moving more quickly, increasing from around 11 kilometres per year half a century ago to close to 60 kilometres per year in 2018.
It’s not an official form of North, but is generally similar to MGA North. People tend to assume that Google knows everything, so they panic when their property title seems to be on a different angle to google maps! Never fear, they’re just using a different type of North.
Remember, one meeting with one of our licensed surveyors at JCA Land Consultants can clear up any concerns you may have about the accuracy, or otherwise, of your property boundaries…no matter which direction they run. So don’t hesitate to give us a call on 9735 4888 if you have any questions or need some assistance.