Land Surveying by the Numbers: Angles & Bearings, Distance Reductions, Closed Traverses, Misclosure & the Bowditch Adjustment, Coordinates, Levelling Runs & Setting Out

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Convert five observed interior angles from degrees-minutes-seconds into decimal degrees, compare their sum with (n − 2) × 180°, spread the angular misclosure equally over the stations and write the adjusted angles back as D-MM-SS text.
• Carry the start azimuth of leg A–B round the traverse with the adjusted interior angles and MOD 360, prove that it closes on itself, add the back azimuths and turn every azimuth into a quadrant bearing such as N 26.9919 W.
• Average three slope readings per leg and judge their spread, reduce the mean slope distance to the horizontal with the vertical angle, look up a temperature correction in ppm from a fictional card and apply it together with a fictional scale factor.
• Split every leg into its latitude ΔN and departure ΔE, add them up, turn the leftovers into the linear misclosure, express it as a precision 1 : x and classify the traverse with a fictional accuracy table.
• Distribute the leftover ΣΔN and ΣΔE over the five legs in proportion to their lengths, adjust every latitude and departure so that both sums close to zero, and find the leg that takes the largest correction.
• Build coordinates for all stations from the start point and the adjusted ΔE/ΔN, close back on A, compute join distances and bearings between points with ATAN plus a quadrant correction (including a due-west join where ΔN = 0) and fix three detail points by radiation.
• Reduce a fictional levelling run from BM1 to BM2 twice – by rise and fall and by height of collimation – run the arithmetic checks, compare the misclosure with a fictional allowance k × √km and distribute it over the set-ups.
• Compute the parcel area from the adjusted coordinates, prepare a setting-out table from station D with backsight to E – bearing, distance and the clockwise angle to turn for four design points – and plot the closed traverse as an XY scatter chart.