- What is the Bowditch compass rule and when should I use it?
- The Bowditch rule (also called the compass rule) is the standard method for distributing traverse closure error when measurements are made with roughly equal precision in both angle and distance — which is typical of most property and topographic surveys. It spreads the total linear error across all legs in proportion to each leg's length. For very precise angle observations relative to distance, the Transit rule (which weights angular and linear components separately) may be preferred, but Bowditch is the default in most field work and the method used here.
- What precision ratio is acceptable for a survey traverse?
- Acceptable precision depends on the survey type. Urban boundary surveys typically require 1:10 000 or better (meaning the closure error is no more than 1 unit per 10 000 units of perimeter). Rural boundary work often accepts 1:5 000. Rough topographic work may pass at 1:3 000. First-order geodetic work demands 1:100 000 or finer. If your ratio is worse than your required standard, check for blunders in individual legs — one mis-entered bearing or distance usually dominates the error.
- How do I enter a quadrant bearing like S 38° 15′ 30″ W?
- Switch the Bearing type selector to "Quadrant bearing." Then in the bearing field for that leg enter the quadrant prefix (N or S), the degrees, minutes, seconds, and the suffix (E or W). The format the calculator expects is:
S 38 15 30 W (space-separated, no degree symbols needed) or S38°15'30"W. Internally the tool converts to the equivalent forward azimuth — S 38° 15′ 30″ W becomes 180° + 38.258° = 218.258°.
- Does the traverse have to be closed?
- No — you can calculate an open traverse (a traverse that does not return to the starting point). In that case the closure error and precision ratio are not meaningful as quality checks, but the coordinate table still gives you the position of each point relative to the starting origin. The PDF export will note whether the traverse is open or closed.
- What starting coordinates does this tool use?
- The tool places the first station at N 0.000, E 0.000 (the origin). All subsequent stations are computed relative to that origin. If you need absolute coordinates (e.g. a known control point), simply add your control Northing and Easting to every value in the coordinate table. Future versions will accept an arbitrary starting coordinate directly in the input.