Construction Stake Out                        

Construction surveying is the translation of construction plans into physical points on the ground that can be used as a basis for the actual construction. The results of construction surveying are seen in almost any urban, suburban, and even rural setting. Almost any roadway, building, or other man-made improvement probably had some amount of construction surveying involved. Construction surveying provides not only the horizontal location of new improvements, but also the vertical information required to ensure that surfaces drain or pipes flow as required.

The stakes and points set during the process of construction surveying are not usually set at the actual construction point, but usually on some sort of offset. This is done so that the survey stake is not disturbed by excavation or other activities that will take place at the actual point of construction. The stakes are marked with an "offset" and a "grade", which provides the construction crew with the spacial relationship of the construction stake to the actual point of construction. The "offset" is the distance from the survey stake to the horizontal position of the actual point of construction, and would typically be three feet for curb and gutter to ten feet for underground pipes. The distance of the offset should be coordinated with the contractor to accommodate any specific needs due to existing field conditions or special equipment, and should be clearly marked on the survey stake (usually by a number enclosed in a circle). The "grade" represents the change in elevation that needs to be obtained from the reference point to the actual construction point, expressed as a "cut" (lower in elevation) or a "fill" (higher in elevation). The grade should also indicate the vertical feature that the grade is referencing, usually a flowline or finished floor elevation. The need for accuracy is inherent in all of the surveyor's tasks, but especially evident in construction surveying. It is not only important to perform all calculations correctly, but also to communicate clearly with the contractor about the distance of offsets and reference points for grades. If the surveyor provides grades to the flowline of curb and gutter and the contractor uses those grades as top of curb elevation, the net result is a construction site that is not going to work as planned! Additionally, scheduling should be coordinated in a manner that minimizes the risk of the stakes being damaged by human or natural activities, as any disturbance to the survey stake may carry over to actual construction. Just as division is the inverse operation of multiplication, construction surveying is the inverse operation of the activities with which the surveyor is usually associated: the gathering of data regarding real points and positions on the ground and representing those positions on a map. The surveyor performing construction surveying is taking a "map" representing proposed improvements or structures and placing that information on the ground. As you can see, the surveyor is literally involved from start to finish of a construction project. At NavTech we recognize the need for survey measurements made prior to or while construction is in progress to control elevation, horizontal position, dimensions and configuration, and, following construction, to obtain essential dimensions for computing construction pay quantities and establishing "as built" conditions. Construction Surveying requires the expert skill of a licensed practitioner well versed in maintaining accuracy, precision, efficiency, measuring and computing values pertaining to such surveys. A construction survey may follow or be made in lieu of a locative survey. On average NavTech will perform over 200 projects a year. These construction sites can vary from a new convenience store to a 1,000 megawatt power plant.