Have you ever gone out to your driveway, looked at your fence, and seen a small square reflector tacked on with a nail? It can be hard to notice, but once you see it you may start to ask yourself: What is that? If you have just noticed that on your fence post, worry not. It is not a practical joke or a spy device. The object in question is likely a survey target.

Let us explain what it is, why it is there, and how it plays a silent, but vital role in your neighborhood’s infrastructure.
What Is a Survey Target?

A survey target is a small reflective maker that is used by land surveyors. They use it when they want to identify precise locations when mapping or constructing. Survey targets can be reflective or adhesive stickers. They can also be nailed on targets through a stake process. This is always done with either crosshair-visible or reflective surfaces. Surveyors use two common devices when a survey target is present: total stations or drones combined with LiDAR. A reflective and/or signal from the survey target enables the total station or drone to identify the precise location.

In the image above, the square survey target marker on the fence post is a prime example of how considerate it is on the face of the marker. By its own size, the survey target is unobtrusive. They are always put on a feature where the surveyor has line-of-sight. Therefore, they must have intended for the target to be there.
Why Is There a Survey Target on My Fence?

If you have found a survey target on your fence post, it was likely done during a survey that was just done, or that you may soon have on your property or in your area. These actions could include:

Widening roads, resurfacing, and other types of roadworks

Installing new services (water, electrical, internet, etc.)

Updating boundary lines or marking boundaries for assets

Municipal development or upgrading neighbourhoods.

Utility company investigations.

Surveyors use these on fence posts, electrical poles, and other things that are securely implanted into the ground. This is done for the most efficient and stable leverage points. That fence post may have been the last reasonably satisfactory anchor point for them.
source: C.R.Kennedy Geospatial
Should You Be Concerned?

In short – No. These targets are not recording activity, they are not causing any adverse effects, no destruction will take place. They are not cameras, they are not monitors. Think of them as surveyors road signs. They hold no significance. They are low profile, have little role (for determining locations), but are not meant for long term.

You can also always call a local surveying company or public works department in your city to confirm what that target was for.
Can You Take It Off?

Theoretically, you should not take it off; specifically if a licensed professional placed it there permanently for a job being performed by municipalities and utility companies. Though, taking it off may interfere with the project, and shut down or stop work, in your area. After the project is complete, the targets will most likely be removed.