The last article I wrote was my experience with the layout of building construction projects and how it has changed in the last 50 years. I am interested in Layout with a Global Positioning Systems (GPS) as I have not had any experience with this type of layout tool, so I did some research on this equipment and will give you a brief dissertation of what I have found out.

From what I understand the first thing that has to be done is a three dimensional (3d) model has to be built of the project on computer. The model will have to be uploaded to your equipment with a stake out list for site work contractors. This is usually done by a design professional that knows this equipment.

The base station with its’ antenna has to be located in an area clear of trees and someplace that it can be anchored for the duration of the job. Making arrangements that the base station can be removed at night and put back in the same place each day, this may require a piece steel tube stock driven into the ground and braced 3 ways, with a piece of threaded rod on the top of it.

After you get the unit supported you need to calibrate the base station using readings from a least 3 different points, but preferably 5 points. In order for base station to give you the proper grading information it has to have errors of less than .05’ if it is over that the unit needs to be recalibrated. If the unit cannot be calibrated to .05’ then the engineer has to be contacted to verify the coordinates of the project.

After the base station is set up the rod that is supplied is used to set up specific points that are needed to give the proper site grading. Cut and fills are easily established using the GPS. Installation of man holes, road grading and underground utility runs can also be laid out with the GPS. When using the rod the trades’ person has to take care to keep it plumb so that the points are installed correctly.

It is very important to check the base station frequently to make sure it is still giving you correct readings. This should be done using known points to verify that the calibration that is calculated is within acceptable tolerances.

Although not stated in any of the information that I have researched I talked with a few of the site contractors that use the GPS for site work and they said that it is easy to learn and saves time, also if some stakes area lost they can be replaced very easily.

In closing I would love to learn how to use this GPS equipment, it is a labor saving device as you only need one person to run the Base station equipment and layout for site work can be done easily and replacement of points can be done with ease also.