The Difference Between a Theodolite and a Total Station

Both the theodolite and total station are tools used to measure horizontal and vertical angles during surveying and engineering projects. Each have particular pros and cons which can be utilized in various situations. In general, it will depend on the time, money, man power, and expertise you have available when deciding on the right tool for your job.

Although theodolites have been used for hundreds of years, the main operation of these tools remains the same. A theodolite consists of a moveable telescope mounted between a vertical and horizontal axes. The angle of each axes can be measured with fairly accurate precision as long as the operator has sufficient knowledge of the tool's use and basic trigonometry. However, the use of a theodolite generally requires the help of at least one other person besides the main operator to help measure and align angles. When precision counts, it is imperative that both operators are properly trained and understand all of the elements of gathering data; this may include leveling the tripod/theodolite and measuring stake, as well as aligning the stake and measuring line to gather accurate data, and finally use mathematical and graphical skills to generate the appropriate output.

The benefits of a total station will outweigh the downsides, in most cases, because of its all-inclusive features and digital integration. A total station integrates theodolite functions in order to measure angles and distance with an EDM (electronic distance meter). Total stations use a system of prisms and lasers to develop digital readings of all the measurements during your job. All of the information gathered with the total station is stored in an external computer where data can be manipulated and added to CAD programs. Robotic total stations are available that allow the operator to work alone with the use of a remote control.

A total station is generally superior to a theodolite because of its digital integration and precision. However, total stations are much more expensive and require not only surveying training, but specific product and software training as well. When completing surveying jobs that span large distances, especially over treacherous terrain, a total station will provide the most reliable and accurate results. For simple plots of smaller areas, a theodolite is sufficient. Before you purchase either tool, ensure it comes with the necessary accessories you'll need on the job. For a theodolite you will want a measuring stake and steel tape, a tripod, as well as grid paper and a pencil to record the data. In most cases, a total station will come with all the necessary accessories you need, however, some may not so always double check!