Readers respond to the May and March issues.

Professional Topography
May 2004

[I] just finished [reading the] article "Tool Chest" in POB. It couldn't have been more timely. We are just finishing a topo of a gravel pit with a 35-foot cut. I was given the job with the idea we could do the whole thing with GPS/RTK. But this was a perfect example of where a little pre-analysis revealed [that] one tool (RTK) would not be feasible for the entire job. Although a large portion of the site is wide open and very conducive to using GPS, due to the sheer vertical cut and unstable ground at the top, and for the safety of the crew, a total station was required. This [tool] would allow [the crew members] to use a zero rod height while standing a safe distance back from both the top and toe, and also provide more accurate data. Also, at the base of the cut, communication was lost and satellites were blocked, not to mention [that] multipath [existed]. And again, there was the safety issue of falling rocks, etc., trying to stand up against the base.