Broken Boundary vs. Irregular Boundary Adj.

[Gromatici]

As I understand it, a Broken Boundary is a Compass Rule Adjustment. Is an Irregular Boundary Adjustment also a Compass Rule Adjustment? I believe they are found at Sec. 5-43 and 5-36 respectively of the 1973 Manual.

[Gromatici]

Nobody likes me!

Here is a PDF of the proposed changes to the 1973 Manual, and they indicate that and Irregular Boundary Adjustment is similar to a Grant Boundary Adjustment. I'll have to figure out if they are really the same or not.

[Gromatici]

Here is a PDF of the proposed changes to the BLM Manual, and it talks about Sec. 5-36- Irregular Boundary Adjustments.

[singlas232]

Eric,

BTW, first thanks for the BLM updates. I never knew those existed.

on page 12 (5-36) of the your PDF updates: my impression of the wording is that an example of the Irrg.Bndry is procedure is requested similar to the Grant Bndry. example in the Manual. Where does it say that both procedures are similar?

I haven't had a chance to compare corner positions resulting from both procedures, but I assume they'd be fairly different.

[Gromatici]

The PDF, down towards the end states that Sec. 5-36 needs to be revised and states that the "Irregular Boundary Adjustment" is similar to the Grant Boundary Method". There are a lot of "irregular" boundaries in the PLSS system here is Santa Barbara, so I want to nail this down.

[Steve Martin]

The 1973 manual 5-36 indicates the procedure for the irregular boundary adjustment, a "modified form of single proportionate measurement". The Latitude and Departures of the closing error are treated differently depending on if the line restored is generally N-S or E-W.

The Borken Boundary adjustment (Sec 5-43) is similar to a Compass adjustment.

The Grant Boundary adjustment (Sec 5-44) is simply a rotation and scale (measured inverse / record inverse).

Try the Irregular Boundary adjustment and the Broken Boundary adjustment on some sample plat data to better understand the difference.

P.S. I believe Bob Dahl's note in the attachment in this thread is an editing note to add a sketch describing the Irregular Boundary adjustment, like the sketch in the manual that describes the Grant Boundary adjustment. It does not mean the two procedures are similar.