A route survey of 18.6 miles was made for a new gas transmission line over rolling brushy terrain. If the open traverse is to conform to second order precision (class II), what is the maximum allowable error of length in chaining? My Surveying Theory and Practice (Davis and Foote, 5th edition) book, Table 4.1 (Methods of Measuring Distance), lists the relative precision of ordinary taping as being 1/3000 - 1/5000. If I calculate 18.6 miles x 5280' / 3000 or 18.6 miles x 5280' / 5000, the precision is much worse than the answer of 4.91' given in the answer key of the CST Level III Sample Examination Questions file. I assume traversing over rolling brushy terrain would dictate ordinary taping. Is my math correct? Is there a general specifications for horizontal control table available on the Internet? The only table I could find was the Standards and Specifications for Geodetic Control Networks from the Federal Geodetic Control Committee.
I would suggest looking at the specs for 2nd order rather than Foote and Davis in this instance. I'm assuming they're meaning a 2nd order survey as promulgated by the NGS.
Second order class II is not "ordinary taping." I think it calls for 1: 20,000 precision, which would get the answer 4.91. You should be able to check this in the FGCC documents or a more modern textbook. (Perhaps Wolf & Ghilani?)
Actually meeting the requirements for an order and class also includes using specified methods, in addition to meeting the precision. If it is an open traverse, how can you get any check on the accuracy? Better read the specs to see if double-run is required to claim 2nd II.
I really like DF&K to help learn, via the old manual methods, what's going on in the instruments and nowadays software. But there are things that have changed a lot, too.
Thanks for your reply! The Standards and Specifications for Geodetic Control Networks I was looking at does not show any field procedures involving chaining. Do you know of any online sources that do?
Thanks for your reply! I think the question is tricky with the inclusion of "rolling brushy terrain" and "chaining." The Standards and Specifications for Geodetic Control Networks, Table 2.1, lists the distance accuracy standards for a horizontal control network. I guess that covers any method of measurement, including chaining, even though chaining isn't listed in the traverse field procedures table.
