Trig Stations around Sydney

Trig stations (or Trigonometric Stations) were critical to surveyors in providing reference points across Australia as they mapped the country. Thousands of trig points were generally sited on the highest and most prominent point in the local area, which means they often provide a great view – although many are now surrounded by trees and bushes. The trig stations or trig points typically consist of a black disc on top of four metal legs or a concrete pillar, while older ones consist of a rock cairn supporting a post and vane.

About a third of trig stations are located on government land; the map and list below are focused on those in and adjacent to national parks and nature reserves. This is very much a “work in progress”: having recently discovered the huge number of these mostly hidden sites, I’ll add more trig points as I find time to reach them! If I’ve missed any in a national park or you’ve got a favourite, please leave me a comment at the bottom!

• Trigs in Sydney’s north (see also Ku-ring-gai Chase National Park trigs and Garigal National Park) 
• Trigs of the Central Coast (including Bouddi, Dharug, Popran and Yengo National Parks)
• Trigs of Newcastle and the Hunter Valley 
• Trigs in Sydney’s south and the Illawarra (including Royal & Heathcote National Parks)
• Trigs of western Sydney and the Blue Mountains
• Trigs of the South Coast (south of the Illawarra)
• Trigs of the Snowy Mountains

MAP KEY
Blue - a trig station referenced from SIX Maps
Green - trig stations I've visited
Orange / Red - trig station on private land or inaccessible / destroyed.

The Most Interesting Trig Stations around Sydney

Many trig stations lie abandoned in thick scrub, offering no views despite being on the top of a hill. Others are located just off a walking track, and provide a magnificent and unexpected view for little effort. The trigs below are some of my favourites, which are worth making the effort to visit.

Sydney’s north & north-west – Garigal National Park 

	TS10447 CROMER HEIGHTS (157m) An easy clamber up some rocks to the trig point rewards with sweeping views over the bushland and to the ocean in the distance. Distance: 3km return. Ease of Access: Easy/Moderate Location: 33°43’50.7″S 151°15’19.9″E. How to get there: Informal track off Red Hill Main Trail What bushwalk passes the trig?: Red Hill Loop
	TS3329 NARRABEEN (135m) While just the metal column remains of this trig station, it’s just off a wide service trail, and give you a great view over Narrabeen Lake and the ocean to the east. Distance: 2.2km return. Ease of Access: Easy Location: 33°42’35.0″S 151°15’51.4″E. How to get there: Follow the Slippery Dip Trail from Deep Creek Reserve What bushwalk passes the trig?: Deep Creek Loop

Sydney’s north & north-west – Ku-ring-gai Chase National Park & Muogamarra

	TS638 ARDEN (191m) This is one of the more challenging ones to get to, but in return you get sweeping views over West Head and out to Pittwater and the Barrenjoey Peninsula. Distance: 3.8km return. Ease of Access: Moderate/Hard (no track) Location: 33°38’02.9″S 151°15’03.4″E. How to get there: Bush-bash up a ridge from the Waratah Trail What bushwalk passes the trig?: Rediscovering the Waratah Trail
	TS7220 BARRENJOEY (104m) The trig point is located on the site of one the original Barrenjoey Head lightstations. It’s a short scramble up from the main Access Trail up to Barrenjoey Head. Distance: 2.2km return. Ease of Access: Easy/Moderate Location: S33° 34.758′ E151° 19.716′. How to get there: Short bush-bash up from the main trail What bushwalk passes the trig?: Barrenjoey Lighthouse
	TS2005 EURO (169m) A relatively easy off-track walk from the Basin Trail. The trig station mast is easy to spot above the trees, and there are great views in all directions. A few Aboriginal engraving sites are nearby. Distance: 3.2km return. Ease of Access: Moderate Location: 33°35’59.8″S 151°17’17.4″E. How to get there: Bush-bash from Basin Trail (West Head) What bushwalk passes the trig?: Secrets of the Basin Track
	TS5929 TABER (204m) An easy walk up from Cottage Point Road via a walking trail to the trig station, which has been damaged by bushfire – you need to continue 100m beyond the trig for a great view over Coal and Candle Creek. Distance: 0.4km return. Ease of Access: Easy Location: 33°37’51.3″S 151°12’28.2″E. How to get there: Follow Ausgrid access trail off Cottage Point Road What bushwalk passes the trig?: Trig Bagging at Cottage Point
	TS4625 WARATAH (182m) Nice views over Coal and Candle Creek from this solidly-constructed trig station, which is accessed via a unmarked bushwalking track off the Waratah Trail Distance: 7km return. Ease of Access: Moderate Location: 33°37’46.0″S 151°13’48.5″E. How to get there: Follow Waratah Track; look for unmarked bushwalking track on the left What bushwalk passes the trig?: Rediscovering the Waratah Trail
	TS2779 WILLUNGA (233m) Willunga Trig is the highest point in Ku-ring-gai Chase National Park, and offers great views toward Pittwater and as far as the city of Sydney to the south. Distance: 1.5km return. Ease of Access: Easy Location: 33°37’46.0″S 151°13’48.5″E. How to get there: Take the Willunga Trail from West Head Road What bushwalk passes the trig?: Willunga Trail

Central Coast – Brisbane Water National Park

TS7212 LYRE (241m) A great trig to visit at sunrise or sunset, with sweeping views over Brisbane Water National Park and Brisbane Water, and the Pacific Ocean in the distance. Distance: 2.6km return from Woy Woy Road Location: 33°27’05.3″S 151°17’56.6″E Ease of Access: Easy How to get there: Lyre Trig firetrail or Bambara Road Trail What bushwalk passes the trig?: Lyre Trig Loop

TS5606 WONDABYNE (251m) Outstanding 360-degree views from this trig point on top of Mount Wondabyne toward Woy Woy and the surrounding central coast suburbs to the east, and Brisbane Water National Park and Wondabyne station to the west. Distance: 7.4km return from Woy Woy Road Location: 33°29’38.0″S 151°16’30.0″E Ease of Access: Easy How to get there: Multiple bushwalking tracks from Woy Woy Road or Wondabyne Station What bushwalk passes the trig?: Pindar Caves and Mt Wondabyne

Sydney’s West – Blue Mountains

	TS692 BALD (1181m) Not only is this an unusual trig in its construction (multiple stepped concentric concrete rings forming a cone shape) but it offers 360-degree views, including Gardens of Stone to the north. Distance: 1.8km (return) via off-track route from firetrail Location: 33°26’46.1″S 150°14’20.7″E Ease of Access: Moderate How to get there: Old Bells Line of Road from Zig Zag Railway
	TS5559 PADLEYS PEDESTAL (1130m) This trig station is located at Padleys Lookout, the highest lookout in the Blue Mountains at the southern point of Hassans Walls near Lithgow.  It offers outstanding views over the western edge of the Blue Mountains and Kanangra Walls. Distance: 0.2km return Location: 33°30’55.0″S 150°09’03.6″E Ease of Access: Easy How to get there: Short walk from Hassans Walls Lookout (off Hassans Walls Road
	TS10371 PORTAL TRIG Spectacular views over Glenbrook Gorge and the Nepean River from the Portal Trig, which is at the Mount Portal Lookout near Glenbrook. The concrete trig station is on a rock platform, which juts out from the cliff. Distance: <100m walk from carpark. Wheelchair-acessilble. Location: 33°46’51.8″S 150°38’17.3″E Ease of Access: Easy How to get there: Large carpark at end of Mount Portal Trail

South Coast of NSW

PIGEON HOUSE (720m) Although the trig station is now covered by a modern viewing platform, it’s the walk up for one of the best views of any trig station in NSW!  Distance: 7.6km (return) Location: 35°20’58.1″S 150°15’55.2″E Ease of Access: Moderate How to get there: Monkey Mountain Road off the Princes Highway What bushwalk passes the trig?: Catching the sunset from Pigeon House Mountain (Didthul)

More Information on Trigs

A Brief History of Trig Stations in NSW

It was agreed at a meeting on 6 February 1867 (attended by the Government Astronomer, Surveyor-General and Deputy Surveyor-General) that a decision be made on the most favourable position for a “Base Line” to be established to support a Trigonometric Survey of the country. The first or baseline trig station was established at Lake George a few years later in 1874 (TS778 Lake George) by the Trigonometrical Survey of New South Wales. The surveying efforts continued for almost fifty years until it was suspended to reduce cost at the outset of WWI, with about a third of NSW covered.

The survey was resumed intermittently between the two World Wars predominantly by the Royal Australian Survey Corps, and by 1966 the geodetic network covered about half of the state. In 1973 a plan was formulated to revise and complete the network, starting in the SydneyNewcastle-Wollongong region and continuing along the coast and then westwards. Many old-style cairn and pole stations were replaced by a concrete pillar with demountable mast and vane. Eventually, over 6,000 traditional ‘passive’ trigonometrical (trig) stations were installed, now managed by NSW Land Registry Services.

The relevance of the traditional trig stations was significantly reduced by the introduction in 2009 of the Global Navigation Satellite System (GNSS) Continuously Operating Reference Station (CORS) networks, or CORSnet-NSW. Covering all of NSW, CORSnet-NSW provides centimetre-level real-time positioning and allows nearby equipment and machinery to accurately determine coordinates for positioning and guidance solutions.

However, while it took only five years to cover more than two thirds of NSW, with 150 active CORSnet-NSW trig stations in place by July 2014, passive control stations are still necessary. Consequently, the Land and Property Information (renamed the NSW Land Registry Services in 2017) initiated a process to select a subset of trig stations to maintain. Multiple criteria (including prominence within the survey network, ease of access, historical significance and monument quality) are used to assess each trig station across NSW and calculate a ‘TrigStar’ score out of 100 and a corresponding rating out of 5 stars. Based on this rating, the top 500-700 (about 10% of the total number of passive trig stations) will be maintained.

Read more: Preservation and Upgrade of Trigonometrical Stations in NSW [PDF] and J.B. McLean – A Short History of the Trigonometric Survey of NSW (1967) [PDF]

Trig Station status

Some trig stations have a letter after the trig station code – this provides additional information on the trig station or survey mark:

Code	Status	Description
D	Destroyed	Evidence was found that the mark is destroyed
F	Found	Mark was found in good condition
N	Not Found	Mark was searched for, not found, but no evidence exists to indicate that it was destroyed
R	Restricted	Mark is in a restricted area and requires special permission for occupation.
S	Subsidence Area	Mark is located in an area identified as being subject to movement
U	Uncertain	Mark was found, however it was in an unstable condition or there was evidence that it had been disturbed or moved.

Resources

There’s a surprising amount of detail on most of the trig stations, with their locations and inspection reports publicly available:

• SIX Maps provide access to a range of NSW primary spatial data – check the “Survey Marks” box to view trig stations (TS) as well as State Survey marks (SS) and Permanent Marks (PM)
• Survey Mark Sketches show the physical position of numbered Survey Control Marks (enter the number only, not the TS prefix to download a report)
• Guide to the History Trigonometric Stations of Sydney’s North by Tony Dawson is the definitive guide to trigs in this area – but it can be hard to find a copy of the book. 
• Geocaching Australia has thousands of trig stations registered as “virtual caches”, with additional information and useful access comments in the logs. There are also maps available, such as this one of all Australia trig station geocaches.