3-D Modeling for GPS Grade Control

Modeling for Grade Control is a very fascinating subject. I worked exclusively with Trimble Terramodel and Trimble GPS grade control over the past two years, so this post is going to reflect that.
The simpliest and most effective way to model is to take a set of plans and create your own as any good Terramodel user probably does anyway. Input you horizontal and vertical alignments, define your slope alignments for superelevations, widenings and what-have-you, and create shapes and Templates. Terramodel is filled with tools to create anything from a simple roadway to the most complex state highway project that you can imagine.
A good majority of the projects that I was involved on came with a digital file of some sorts. That in and of itself is a good thing. You can get your project defined and you dtm and background maps created very quickly, which allows you to get the base station established and the site under control and the files loaded into the dozers, and graders in a minimum amount of time, which is, after all, the name of the game it seems.
The downside of using the digital files is this. Most files provided to me were submitted to the Dept. of Transportation by the engineer who was contracted for the design and these files, at best, are about 85 to 90% complete. Widenings, Taper lanes, Special ditches, Turning Lanes, .etc, are added, sometimes manually, at a later time and, invariable, the Model submitted to the State will not be updated. Big Headache when you have several projects going and are on the other side of the state! When you discover something is missing and make the call to inquire why, you will always get the speech about the paper plans over-rule the digital files, even though the paper plans are supposed to represent the digital files. It taught me a valuable lesson in Data Prep. The digital model provided, will get you up and running, BUT, it needs to be checked against the paper plans and the final model, especially your Blue-topping or subgrade layer, needs to be thoroughly checked against the plans and cross-sections. The State will hold to the paper sheets over all else, unless, god forbid, a mistake is found.
I write this as a solo surveyor that worked for a Construction Company. I comprised the entire Survey, Cadd, GPS, departments, and my comments are based on personal experience.
When I was not Establishing a base station, calibrating a site, field staking or Gps troubleshooting, I built the files for grade control. In retrospect, I did not always have the time to build it by the book and sometimes relied on the models provided as a quick grab-and-go alternative to get up and running.
The construction industry has embraced GPS grade control and the days of the conventional survey crews are numbered. Surveyors are becoming consultants, file builders and GPS troubleshooters. Our do whatever it takes to stay ahead of the equipment mentality is evolving into a create a perfect model so a anyone with a little rover experience can do the stakeout mentality. It will be a transition to say the least. But, in the long run, a rewarding change.