Many contractors regularly utilize single point control. It is a great way to use your GPS machine control system for small designs, stockpile calcs or even as an ad hoc laser. Unfortunately, due to the "single point" nature of the process, we have seen it cause problems that could have been avoided. If you need a refresher on how site control works, check out this blog post. It will help you understand why single point control is not used on engineered projects and why you need to be careful using it on yours.
You hired the project Engineer to place your control, you surrounded the site with points and shot in more than five control points. What could go wrong now? A lot, if you don't use some independent checks to verify that your 3D model matches up to the real world.
Let's imagine your project is drawn on a piece of paper and you have to place it on a globe. To get the paper - your project - to conform to the shape of the globe, you would need to pin down all of the edges. If you only pinned down one side or just three corners, the paper would drift away from the surface of the globe on the side opposite the pins. I may have oversimplified a little, but site control places your GPS machine control file in the real world in much the same way. To get your 3D model in the right place horizontally and vertically, you need to "pin" down the edges. A "pin" or two in the middle is...
Why hire the design Engineer's surveyor, you ask? There may be someone that will do it cheaper, faster or you want to help out your brother-in-law's new surveying business. All of those are great reasons to hire someone else, but not good enough. The engineering firm that designed the site is the only one that has all of the information necessary to set your site control and the authority to figure out how to fix it if there is a bust.
Poor site control is one of the most common (and avoidable) problems encountered by Quantum's clients. Improper site control leads to a host of issues that can cost a grading contractor a lot of time and money. To get your projects off to a smooth start, Quantum's experts will take an in depth look at site control, how to set it up and how it effects your projects.