Considered the foundation of many surveying projects, total stations have become an integral piece of kit and are one of the go-to measuring instruments in many industries – from construction setting out and BIM, archeological mapping, accident scene investigation, civil engineering and more.
Combining an electronic theodolite and an electronic distance metre (EDM), a total station can provide accurate and precise measurements of angles and distances, making it a vital piece of equipment in the construction, engineering and land surveying sectors.
Here, we’ll delve into the specifics of total stations, from their components to their varied uses.
Total stations consist of three key components: Telescope and optics (theodolite), EDM and an Electronic Control Unit.
A theodolite is used to measure horizontal and vertical angles. It does this by combining its optical plummet, the level bubble and calibrated circles to find angles.
It is through the telescope that we can target angles, which are then displayed on the screen. Having high quality optics is essential for obtaining accurate readings. And, naturally, the accuracy of readings has a knock-on effect on the efficiency of surveying and construction projects.
The principal function of EDM is to measure the distance between a total station and a reflector. It does this using electromagnetic (EM) energy which comes in two forms: electro-optical (i.e. infrared or laser) and microwave.
There are several EDM methods. The prism method involves the total station sending out infrared waves which are reflected by a prism, typically mounted on a pole. With the reflectorless method, there are no prisms. Instead, a visible red laser beam is used to indicate measurement points from reflective surfaces.
The final key element of a total station is the electronic display. Its function is to provide a visual overview of the total station’s activities and readings. There are various menu items which users can press to navigate the device.
The essential information it displays are horizontal distance, vertical distance, horizontal and vertical angles as well as key elevations and coordinates. Some total stations, such as the Trimble C5, have dual colour touchscreen displays for ease of use.
Total stations are useful instruments for modern surveying projects as they provide insight into measuring distances and angles with pinpoint precision.
The key functions and capabilities of the instruments are outlined below:
In the total station’s optics is a small emitter. It is that emitter that generates an infrared carrier signal which is then reflected either by the prism (using the prism method) or the item being surveyed (in the reflectorless method).
The total station then reads and deciphers the pattern on the signal which in turn calculates the distance. The accuracy of a total station is typically 5-10mm per km with the range of EDM varying between 2.8-4.2km.
Total stations can measure both horizontal and vertical angles. Horizontal angles are a representation of the rotation in the horizontal plane – also known as azimuth. The vertical angle meanwhile, represents the rotation in the vertical plane – the elevation or zenith.
Accurate angle measurements – which can be determined using a total station – are hugely important when it comes to accurately plotting relative positions, orientations and points in surveying and constructions.
The total station’s microprocessor has a memory unit that records calculations, readings and measurements. This data can be stored internally on the total station or externally, via exporting in various formats, including BIM and CAD software.
What can you use a total station for? The versatility of a total station means it has a number of applications when it comes to surveying and mapping, including:
Total stations are used in land surveying for taking precision measurements, including angles and distances between objects. This makes them ideal for boundary surveys and topographic mapping. Typically, they can measure distances of approximately 2.8km, depending on the apparatus and weather conditions.
They also play a vital role in establishing control points through the provisions of precise angle and distance measurements. This enables methods, such as triangulation and trilateration to plot coordinates – providing accurate spatial references for surveying.
Additionally, provided a direct line of sight can be established between two points, total stations are capable of determining the coordinates of unknown points in relation to known coordinates. Total station position data can be integrated with position data from a separate GNSS receiver when using the same data logger and software.
Total stations are credited with increasing productivity and accuracy by simplifying the construction layout and positioning process.
It reduces the time it takes to execute the construction setting out process, while simultaneously increasing accuracy – reducing the need for revisits and any potential costly errors later down the line.
Using a total station for setting out, contractors can upload coordinates directly from BIM models or drawings and lay out a project with a high level of precision. The technique can also be performed by only one person, making it more efficient and improving workflows in a team.
Total stations are ideal for measuring structural movements and natural processes. Almost all total stations are capable of monitoring and analysis, however robotic total stations can track very slight movements and take automated measurements. This automation offers a quality assurance of the measurements as they remove any chance of human error.
The total station can also measure the horizontal and vertical angles of slopes and deformations. From these observations, 3D images can be computed. This practice functions as risk avoidance as it allows contractors to identify potential issues with the terrain early on before any construction work begins.
While total stations are already a major technological feat, the device is constantly being refined and improved. Today, the instrument can be used to assist in both imaging and scanning. For example, the Trimble SX12 is an all-in-one laser 3D scanning solution for surveying, engineering, and scanning professionals. It’s capable of collecting high-density 3D scan data, enhanced imaging with Trimble VISION™, and high‑accuracy positioning data.
Robotic total stations may one day completely replace manual ones, due to their increased accuracy. The telescope of a robotic total station such as the Trimble S9 for instance, can move in all directions up to 360 degrees, both horizontally and vertically.
It can also be tilted to achieve the perfect angle. Most robotic total stations have an accuracy of 1-2 mm and the telescope can automatically turn and adjust using a built-in motor. This means only one person is needed to take measurements.
More benefits of a robotic total station:
Scanning capabilities have been a part of robotic total stations since as early as 2007 with the launch of the Trimble VX. Today, some advanced total stations come equipped with high-resolution cameras that can be used to photograph detailed images of terrains and structures.
As mentioned above, one such instrument with this feature is the Trimble SX12 which, like its predecessor the SX10, has a Trimble VISION™ camera system. These images provide complementary visual context to measurements and angles, allowing surveyors to gain a clearer understanding of a site and its conditions.
Imaging total stations can take high-quality images of sites as well as calculate their measurements. This makes them very useful when it comes to creating as-built documentation – a vital step in construction projects.
Combining images and measurements in this way creates a comprehensive and traceable surveying record of a site that can be used by everyone from contractors, to architects, to facilities management.
Total stations are also useful tools in the domain of architectural preservation and documentation.
They are capable of capturing high-resolution images of historical buildings, facades and features. These images can then be used to draw up 3D models for the purpose of restoring or conserving a building or site.
Additionally, total stations can be used to document artefacts and sites that are important to cultural heritage.
Capturing detailed images, measurements and angles without comprising the sites and structures makes them helpful tools for preserving and studying cultural items.
Finally, total stations are important tools for the visualisation and marketing aspect of construction. Using measurements, angles and images, it is possible to create renders and virtual tours with the use of mixed reality to exhibit the project to clients, stakeholders and other concerned parties.
The efficiency of construction projects has been greatly increased by the integration of total stations with Building Information Modelling (BIM) technology.
As total stations can communicate directly with BIM software, data can be transferred in real-time, allowing architects, engineers and construction workers to quickly and easily determine the viability and safety of a project and determine any potential issues using technology such as clash detection.
A total station is a surveying tool consisting of a theodolite, an EDM and a control panel. It’s used to provide accurate measurements of horizontal and vertical angles as well as distances. It is therefore a vital tool for land surveying, engineering and construction. Additionally, it provides data that can be translated into maps, construction plans and 3D models.
Total stations are now considered essential equipment for surveyors across the globe, with a range of functionalities enabling contractors to work efficiently and quickly.
At KOREC Group, we specialise in supplying state-of-the-art survey equipment to professionals in the surveying, geospatial, engineering and construction industries. We make it our mission to ensure any surveying or mapping task you undertake is done easily, on budget and on time.
If you’re in the market for a total station, check out our comprehensive range of Trimble total stations, including specialised instruments for surveying and construction. Prefer to hire than buy? Our fully supported survey equipment hire service may be what you need, just give us a call to see how we can help you.