TPC includes tools to help you with cadastral surveys. These surveys involve the Public Land Survey System. Additional information can be found the in 1973 and 2009 editions of the Manual of Survey Instruction, Bureau of Land Management.
Most of the geodetic tools used for cadastral (PLSS) surveys are available in the Premium edition, but the PLSS sepcific tools for restoring lost corners are available only in the Professional edition.
TPC introduced these Cadastral survey tools in TPC Desktop 2011 (August 2011). Feedback obtained from field usage will be incorporated in the future releases of TPC Desktop. Please send any comments and suggestions to firstname.lastname@example.org.
The Public Lands Survey System specifies that True Bearings and ground distances be used to map out townships and sections. TPC includes special tools to work with the PLSS. They will come into play as you enter data in a traverse, plot lines in a drawing and compute points via COGO.
For computations along East-West lines, TPC can switch from geodesic to rhumb lines per the Manual of Survey Instruction.
Computations on the PLSS assume a project elevation. TPC lets you specify a project elevation as part of the survey factors. To set the project elevation:
TPC includes the tools to compute mean course elevations as well. These options compute a mean elevation for each course and scale the course distance accordingly. This is a more rigorous approach to scaling elevation and one you will want to consider if you have significant elevation changes within a survey.
To enter PLSS data in a traverse, format the Traverse View to include 'True Bearing' and 'Geodetic Distance' at your project elevation. See Entering PLSS Data in a Traverse.. When you enter PLSS data, TPC switches from cartesian coordinate computations to geodetic computations. So just as you would expect, entering a distance of 40 chains in a true West direction carries the latitude of the occupied point to the computed foresight along the latitudinal arc.
TTPC includes tools to draw your PLSS data. This includes carrying true bearings through geodetic positions and plotting the equivalent cartesian plane coordinates. As a result, East-West lines appear curved in the drawing to accommodate the latitudinal arc. TPC can also label survey lines with geodetic ground distances at the project elevation. See Drawing PLSS Data.
Many of the COGO tools now include pulldowns that allow you to choose the direction and distance types you want to use. Simply choose the PLSS options from the lists and you are doing PLSS COGO. See Doing COGO with PLSS.
For instance, the Offset Interval routine lets you do cardinal offsets from a random line to a true line.
Some COGO computations, like offsetting points on a random line to points on a true East-West line, have a [x] Latitude Arc option. This tells TPC to switch from using geodesic line to using rhumb lines.
TPC contains the tools to compute the positions of lost corners in the PLSS. These include adjustments (Irregular Boundary, Grant Boundary and Angle Points of Meander Lines) and COGO routines for Single Proportion, Double Proportion, 2-Point and 3-Point Control (use Double Proportion command).
When you set out corners, you set up the traverse to display true bearings and ground distance. The traverse data becomes your notes for setting out the corner. See Set Out Corners.
TPC includes a least squares network adjustment which you can use with your PLSS data.
Most of the geodetic tools used for cadastral (PLSS) surveys are available in the Premium edition, but the PLSS specific tools for restoring lost corners are available only in the Professional edition.