Stationing for construction surveyors: a meticulous process

Survey stationing is a slow and meticulous process that requires a high degree of accuracy. It is essential that all constructions (bridges, roads, residential and commercial buildings, or any other infrastructure) are located in the right place. Any mistake can involve exorbitant cost overruns. In the surveying business, this is a challenge, because to stake out or survey with precision, it is first necessary to have the most precise stationing (positioning) possible.

Possible sources of error in setting up the surveying device

In setting up for surveying, there are two risks of error: an imprecise setting up (positioning) and a level error which is the maladjustment of the level of the rod. What interests us in this article is the positioning error and how to reduce the risk for more effective positioning!

Is relying on a surveyor positioning system a risk for a survey stationing mistake?

When surveyors use a positioning system, they aim for 2 to 3 different landmarks. Then the surveying device’s positioning system calculates and compensates for any wobble between the points used to swing.

What’s wrong with the conventional positioning system that a surveyor has in construction?

The problem with the classic positioning system in construction is that if the points used by the surveyor do not match each other or if the layout is taken with a surveying rod, it leads to a positioning error that the system of positioning of the device (total station) must compensate by taking an average between its points. Thus, for each station at different locations with the same landmarks, the positioning of the construction device will be moved from left to right and from bottom to top.

A concrete example of a costly error of incorrect positioning of the device (Total Station) on a construction site

Let’s say you are a construction surveyor and you are setting up in a place to stake anchor bolts for a bridge girder and you have a tolerance of 5 mm (0.19685 of an inch).

If your rig setup configuration offsets 5-10mm (0.19685 to 0.393701 of an inch) on one side and you then reinstall the rig positioning system (Trimble, Leica, Topcon, or any other), your configuration decompensates on the reverse side. Therefore generates an implantation error varying between 10 and 20mm (0.393701 to 0.787402 of an inch).

Positioning errors caused by inaccurate station settings can quickly accumulate

In the example above, the inaccuracy of setting up the instrument is at least 10 to 30 mm (0.393701 to 1.1811 of an inch). Also, when you consider the possible error caused by the level of the rod (which can be set incorrectly) or human errors, it adds up fast!

On the human side, when setting up the rod, it is very difficult for the surveyor to keep it straight (human error) and even if he manages to keep it level, 95% of the time the rod is incorrectly adjusted.

By adding all the aspects shown above in the example of bridge layout surveying, the inaccuracy in construction surveying becomes major, which can be very costly!

How to improve the accuracy of construction surveys then?

For perfect consistency between different measures and layouts on building survey setups at different locations, the human factor should be eliminated as much as possible.

How to eliminate human errors when setting up the device?

To eliminate human error when setting up the surveying apparatus for construction and to improve accuracy and speed, surveyors need fixed targets placed at strategic locations that can be aimed directly together with the device, they guarantee perfect agreement between points over long distances in all kinds of conditions (including bad weather).

Targets ensure perfect positioning with optimum positioning speed to make life easier for construction surveyors with maximum accuracy.

A positioning system with reflective targets to improve stationing

TDR360 has thoroughly investigated this problem and found the solution for surveyors. The secret to a perfect positioning of the surveying station (Total Station) with an irreproachable precision is to use fixed points of reference which one can aim directly with the device such as the reflective targets TDR360 or the targets of 3D scanning.

No matter your type of instrument (Trimble, Leica, Topcon, etc.) simply place them in strategic places. These very easy-to-use targets allow you to position your device extremely quickly with optimum precision.

Designed with premium materials to give you: the best possible measurement feedback, no matter the distance, and the best aiming angle, rain or shine, if you see the target, it works.

Here’s a video example of how it’s used to improve survey stationing to build a road.