NSPS CST Level III cheat sheet

Horizontal angle closure check: sum of interior angles of an n-sided traverse = (n-2) x 180 degrees; angular misclosure is distributed equally among the angles before azimuths are carried forward.

Traverse linear misclosure = sqrt(easting_error^2 + northing_error^2); relative precision = total traverse length divided by linear misclosure, reported as 1:N.

Latitude = distance x cos(azimuth) and departure = distance x sin(azimuth); north and east are positive, south and west negative, so closure error is the negative sum of latitudes and departures.

Differential leveling misclosure allowance commonly scales with loop length (for example 0.05 ft x sqrt(miles) for third-order work); a closed loop must return to the starting benchmark elevation within that tolerance.

Curvature and refraction combined correction in feet = 0.0206 x D^2, with D in thousands of feet (0.0675 x D^2 when D is in miles); refraction offsets about one-seventh of the curvature effect.

Earthwork by average end area: volume = L x (A1 + A2) / 2; by prismoidal formula: volume = L x (A1 + 4Am + A2) / 6, where Am is the mid-section area.

Stake marking convention: cut is written above the grade line and fill below it; a station stake shows the station plus offset and the cut or fill to finished grade.

Construction layout control should be tied to at least two permanent reference monuments so a lost point can be reset by intersection from surviving control rather than by remeasuring from a disturbed point.

Record boundary evidence hierarchy: written record documents (deeds, plats, court orders) control over monuments, monuments control over courses and distances, and courses and distances control over area.

Deed closure check: convert each bearing-distance call to latitude and departure, sum them, and compare the resultant to the perimeter; a large misclosure signals a transcription or bearing error rather than a field problem.

Coordinate system note: state plane grid distance differs from ground distance by the combined factor (scale factor x elevation factor); ground distance = grid distance / combined factor.

Metadata required for a defensible deliverable includes datum and epoch, coordinate system and units, survey date, instrument and method, positional uncertainty, and the names of the responsible surveyor.

Area by coordinate method (shoelace): twice the area = sum of X(i) x Y(i+1) minus sum of Y(i) x X(i+1), taken around the closed figure; the result is signed, so take the absolute value.

Metadata accuracy reporting follows a stated confidence level; horizontal uncertainty is often expressed at 95 percent confidence as roughly 2.45 times the 1-sigma RMS value for a 2D network.

Version control rule: every transmitted dataset carries a unique revision identifier, and superseded files are archived rather than overwritten so the delivered record can be reconstructed.

Total station setup error budget: centering error affects short shots most, so keep backsight and foresight distances balanced to cancel residual instrument centering and collimation error.

Two-face (plunge) observation cancels collimation error, trunnion axis error, and horizontal circle eccentricity; the mean of face-left and face-right readings is the corrected direction.

Resection from three or more known points yields a position plus an orientation; a weak geometry (points clustered on one side) inflates the uncertainty even when the residuals look small.

GNSS RTK fix requires a minimum of five satellites with carrier-phase ambiguity resolution; float solutions are typically an order of magnitude less precise and should not be used for boundary or control work.

GNSS positional dilution of precision multiplies the ranging error: GDOP, PDOP, HDOP, and VDOP each express the geometric contribution, so a high PDOP invalidates an otherwise clean fix.

Traverse station spacing rule of thumb: keep sight distances similar and long relative to the target width, since angular error propagates into position error in proportion to distance.

Monitoring and as-built checks should include redundant independent measurements, such as a taped or GNSS check on at least one traverse leg, to detect gross blunders before leaving the site.

Scope control: the deliverable list in the contract governs acceptance, so any added product (for example a topographic surface or a CAD file) must be priced and documented as a change before work begins.

Quality review is a defined stage, not a final read-through: an independent reviewer who did not perform the work checks computations, closures, and the map against the field notes.

Error propagation for a sum or difference of independent measurements adds variances, so total uncertainty = sqrt(sigma1^2 + sigma2^2 + ...); uncertainties never simply add as absolute values.

Cost-to-complete tracking compares budgeted hours per task against hours charged; a task overrunning its budget signals either a scope change or a productivity assumption that must be corrected for the remaining work.

Deliverable file standards typically specify units, coordinate system, layer naming, and a metadata file; a dataset missing its metadata is incomplete regardless of geometric quality.

Chain of custody for records: field notes, raw data files, and computation sheets are retained for the period the jurisdiction requires and are never altered after the fact; corrections are made by dated annotation.

Utility locating rule: call the one-call service before excavation and respect the marked tolerance zone around each flagged utility; markings expire and must be refreshed for long projects.

Traffic control in a work zone follows the manual on uniform traffic control devices: advance warning signs, taper length, buffer space, and a trained flagger where traffic must be stopped.

Field notes must be written in ink, with errors struck through (not erased) and initialed, because the notes may be produced as evidence and erasures invite challenge.

Occupational exposure to silica dust during concrete or asphalt cutting requires wet methods or respiratory protection; noise above 85 dBA averaged over eight hours triggers a hearing conservation program.

Access to private property requires permission from the owner; a surveyor's right of entry varies by jurisdiction and does not automatically authorize entry onto every parcel in a project area.

Weather limits for optical work: heat shimmer degrades long sights, and wind affects plumb-bob and prism-pole stability, so long shots should be taken when atmospheric conditions are stable.

Least squares adjustment output includes residuals, standard errors of the adjusted coordinates, and a reference variance; a reference variance far from 1.0 indicates the assumed measurement weights do not match the actual data.

A residual is the adjusted value minus the observation; a standardized residual much larger than about 3 signals a possible outlier that should be investigated, not automatically deleted.

Degrees of freedom in an adjustment = number of observations minus number of unknowns; a network with zero redundancy has no way to detect blunders and cannot be checked.

Coordinate transformation by least squares: solve for translation, rotation, and scale between two control sets, then check the residuals; a scale factor far from 1.0 suggests a units or projection mismatch.

Digital terrain model checks include comparing spot elevations against the source points, verifying breaklines along curbs and channels, and confirming the surface boundary covers the full area of interest.

Volume comparison between two surfaces is the integral of the elevation difference over the overlap; where the surfaces do not share a boundary, the computed volume is not a valid cut-and-fill balance.

Horizontal control accuracy is expressed as a relative positional uncertainty, while vertical control is expressed as an absolute elevation difference; the two are specified and tested separately.

Monument stability rule: set control on stable, deep-seated marks rather than on pavement or backfilled trenches, and re-observe existing control at the start of each project to detect movement.

A closed traverse returning to its starting station provides a closure check; a closed-loop traverse that starts and ends on different known points provides both a closure and an orientation check.

Leveling loop misclosure is distributed in proportion to the accumulated distance from the start, not equally per setup, because error grows with the number of instrument setups.

For GNSS-derived control, observations should span a minimum session length and use fixed-height tripods or calibrated poles; antenna height blunders are the most common cause of vertical misclosure.

Reference marks and azimuth marks protect a primary station: the azimuth mark fixes orientation and the reference marks allow recovery if the primary monument is disturbed.

Metes and bounds description components: a commencement, a point of beginning, a series of calls (bearing, distance, and monument), and a closing call that returns to the point of beginning.

Ambiguity order in a description: natural monuments control over artificial monuments, artificial monuments over courses and distances, and courses and distances over area or quantity.

A description that fails to close by a significant amount is a scrivener's error candidate; the office must document the discrepancy and the basis for the correction rather than silently adjusting the call.

Adjoiner and area-of-overlap analysis: computing the overlap between a deed figure and the occupied parcel quantifies the conflict before any opinion on the boundary location is formed.

Plat content typically includes the boundary, lot and block, bearings and distances, curve data, monument ties, area, basis of bearing, and the surveyor's certificate and seal.

Record research sequence: chain of title, prior plats, road and easement records, and adjacent deeds; each document is read for the boundary it creates, not only for the parcel it names.

Offset staking: set stakes at a constant offset from the design line so construction equipment does not disturb them, and record the offset distance on each stake.

Slope staking for a cut or fill: horizontal offset = vertical difference x side slope ratio, so a 2:1 fill 4 ft high requires an 8 ft horizontal offset from the catch point.

Grade check by trigonometric leveling: elevation difference = horizontal distance x tan(vertical angle) plus instrument height minus target height; curvature and refraction are negligible on short construction shots.

As-built comparison reports the difference between design and measured position for each feature; a tolerance stated in the contract (for example plus or minus 0.05 ft) governs acceptance, not the surveyor's preference.

Structural monitoring points must be identical between epochs: same point, same prism height, same reference control, otherwise the apparent movement includes the setup difference.

The surveyor's seal attests to personal responsibility for the work; a seal applied to work the licensee did not direct or review is a violation regardless of technical accuracy.

Conflict of interest rule: disclose any financial interest in the property or project, and decline work where an independent professional judgment cannot be given.

Client communication record: written confirmation of scope, assumptions, and exclusions protects both parties and reduces the chance of a later dispute over what was promised.

When the field evidence contradicts the record, the deliverable states the evidence, the analysis, and the conclusion separately; the opinion is labeled as an opinion, not presented as a measured fact.

Confidentiality applies to client data and to information about individuals encountered during fieldwork; it does not override the duty to report a discovered hazard or a legal requirement to disclose.

Typical retention: raw field data and computation files are kept for the jurisdiction's statutory period, and a project archive should allow a later surveyor to reconstruct the basis of the boundary opinion.