As a new survey trainee, there’s a lot that is new and interesting about on the job experience. The team at Compass Consulting Surveyors has helped me gain a continually expanding understanding of the jobs surveyors undertake and, importantly, the tools used to undertake those jobs. From tape measures to total stations, there’s a large range of equipment involved in delivering accurate and reliable surveys that suit each client’s needs.
On the Belt
There are many bits and pieces that a surveyor carries in their toolbelt.
The contents of my field bag: tape measure, tie ribbon, textas, spirit level (the orange item, with a few texta marks from where it’s been used as a ruler), gloves (a true Godsend in the cold), a cloth, plumb bob (without gammon reel, for more on that keep reading), a few washers, and lots, and lots of nails.
Plumb Bob/Gammon Reel
The Plumb Bob is a piece of equipment that dates back thousands of years. It is used to determine a straight line down from a vertical point. The Gammon Reel (an external reel that holds a cord attached to the Plumb Bob) is coloured specifically to act as a type of target when using the laser measurement system on the Total Station.
Hand Tools
While in the field, surveyors require a range of tools to complete their work safely and efficiently.
- There are drills of different sizes for putting in marks
- Saws for carefully removing branches intruding into the jigger’s line of sight or giving access to marks that have been hidden by foliage
- Sledgehammers for putting in stakes and PMs
- Metal detectors, shovels and crowbars for finding buried marks
- Witches hats/signs for protecting tripods and workers
- Dollies for putting in star pickets
- Marking paint for spraying marks and GCPs
- Chainsaws for opening up old tree blazes
- Pit keys for opening up sewers and sometimes a tape measure kept separate for that kind of work
- PPE – hard hats and sun hats, fluoro vests and even snake gaiters
Stakes and Pegs, Plastic and Wood
At Compass Consulting Surveyors we use both recyclable plastic (polypropylene) pegs, and wooden stakes. The lightweight pegs are easier on the surveyor in the field, increasing the speed at which they can work. And have less chance of splinters!
Total Stations/Prisms/GNSS/Digital Level/Tripods
Tripods are used as a level platform to hold equipment such as total stations (known as a “jigger”), GNSS and digital level. They are one of the simpler but absolutely essential pieces of equipment that surveyors have on hand. Tripods have adjustable legs with spiked feet to ensure stability on uneven ground, and a spirit level attachment (tribrach) to confirm a level base for instruments.
The jigger, like the tripod, has its roots in history. Jiggers and their controllers are an electronic hybrid of their ancestors, the theodolite and steel riband. Today surveying is made easier due to the jigger’s ability to remotely track and then measure to prisms mounted on other tripods or carried by the surveyor. The jigger measures from the lens to, most commonly, a prism or multiple prisms, and gathers data on distance, angle and elevation. It can be remotely controlled by the surveyor using a controller which runs a system similar to Windows 7. A surveyor can use known points to determine an unknown point by setting up a series of tripods and exchanging the jigger and prisms. Once the surveyor has made connections between known points, they can then set the jigger up over the unknown point. They then measure the angles and distances from the known points and the jigger determines where it is in reference to those points.
GNSS (Global Navigation Satellite System) – which GPS is part of – can be set up over a monument alongside an internal or external radio (base station) and determine location. GNSS is also used as a non-monument-based form of surveying, which is especially useful in places where in-ground markers are prone to movement due to tectonic activity, such as New Zealand and Japan. Through the use of a base station and rover (handheld GNSS) along with the complex equations made by the GNSS software in real time, the level of error experienced by this GPS is drastically lowered from the uncorrected 2 metres (like in your phone’s GPS) to measurements accurate to 15 millimeters horizontally and 25 millimeters vertically – or better. This level of accuracy makes it ideal for Identification surveys, Marking Boundaries, and collecting data for Drone surveys.
The digital level is used to measure level, funnily enough! It takes readings from a barcoded staff to ensure that its measurements are as exact as possible, with 0.2mm accuracy. The use of this level reduces the human error that comes form using a third order level or optical level, while increasing the speed that work can be completed.
Survey Poles: more than just a stick
Calibrating survey poles ensures that they’re accurately measuring vertical positions. It can become tricky to determine which angle is directly up while working, particularly in hilly country, so surveyors must make sure that their equipment is on the money. This extends to other equipment as well, especially equipment involved in assessing how level tripods are. For this, we have our tribrachs sent away to be professionally recalibrated to ensure the utmost accuracy.
Drones
Drones in the world of surveying can be used to create 3D models of terrain. This is done by stitching together a large collection of aerial images though the use of Ground Control Points or GCPs for short (“X”s placed pre-flight) and a photo capture program. This is then tied together with information on ground heights and contours to give the patchwork of images some depth. At Compass Consulting Surveyors we often work together with Morrison Aerial Robotics for extensive projects. See our blog on UAV/Drones for more.
The diversity of equipment that surveyors use was something I hadn’t realized before starting. From a family history and personal involvement in agriculture I can testify to some pre-existent competency with a handful of the equipment we use, but there were tools of a surveyor’s trade that I hadn’t even heard of before. I look forward to continuing to grow my understanding and skill with the team at Compass Consulting Surveyors.
Josh Healey
Survey Technician – Trainee
