Sri Lanka Licensed Surveyor Exam common mistakes
Sri Lanka Licensed Surveyor Exam · Understand the traps and how to avoid them.
Computing the parcel area and boundary line from the deed schedule alone, then presenting the fence line on the plan as the legal boundary without reconciling the registered survey plan, field monuments, and occupation.
Deed distances and bearings look precise and are easy to compute, so candidates treat measurement calls as the boundary rather than as evidence to be weighed against the plan and the ground.
What to do instead
Reconcile the deed, the registered survey plan, original Crown grant or permit boundaries, monuments, and occupation before stating the boundary. Apply the boundary-evidence hierarchy and record every discrepancy and the basis for the adopted line.
Using GNSS-derived WGS84/ITRF coordinates as if they were already Sri Lankan grid coordinates, or applying a distance scale factor but leaving grid bearings uncorrected for meridian convergence.
Projection mathematics is less intuitive than field measurement, and software often displays latitude/longitude and grid coordinates side by side without warning.
What to do instead
Identify the applicable datum and projection before any coordinate is used, compute grid-to-ground scale and convergence for each line, and transform with documented parameters. State the datum, projection, and transformation in the plan and report.
Accepting a closed traverse when the linear misclosure is below a chosen tolerance, without first checking angular misclosure and without adjusting coordinates before computing final areas or setting out.
Adjustment software returns coordinates that look final, so candidates skip the manual angular check and the residual analysis that reveal systematic errors.
What to do instead
Check angular closure against the expected geometric sum before assessing linear closure. Distribute misclosure by an appropriate method, report residuals and final adjusted coordinates, and never compute legal areas from unadjusted coordinates.
Treating a registered title or deed as proof of the physical boundary and advising that an existing fence is the legal line, without examining the survey plan, monuments, and statutory boundary rules.
Candidates conflate ownership with boundary location because title documents appear authoritative and the distinction is rarely tested in everyday practice.
What to do instead
Separate title from boundary in every answer. Examine the registered plan and field evidence, identify encroachment or prescription issues, and state that registration does not by itself fix the physical boundary.
Setting a boundary peg from a single RTK fix with no base station, no repeat occupation, and no check against an existing control point.
RTK gives a fast fix and a small displayed uncertainty, which creates false confidence in a position that may be in the wrong datum or affected by multipath.
What to do instead
Use a properly referenced base or network RTK, occupy each boundary point more than once, check against known control, record PDOP and fix quality, and transform to the local datum before pegging.
Setting out from coordinates copied from a CAD drawing without confirming the drawing's datum, units, and scale, and without closing the setting-out to site control.
Drawings look authoritative and the coordinates are easy to export, so candidates assume they are in the same system as the survey control.
What to do instead
Establish site control first, verify units and datum against the design drawing, compute setting-out data from the control, and independently check at least one point before construction proceeds.
Drawing smooth contours by interpolating scattered spot heights while omitting breaklines, then stating that the map meets a contour accuracy standard.
Contours are visually persuasive and interpolation is quick, but sparse spot heights cannot represent ridges, drains, or embankments without breaklines.
What to do instead
Capture breaklines and verify the vertical datum before contouring. State the contour interval, source data, and achieved accuracy, and use a TIN with breaklines rather than unqualified interpolation.
Using a DSM or web-mapping imagery as if it were a surveyed DTM or orthophoto, without ground control points and without reporting the achieved RMSE.
High-resolution imagery and elevation models are freely available and look accurate on screen, so candidates overlook the difference between a surface model and a surveyed product.
What to do instead
Use ground control, report checkpoint RMSE, distinguish DSM from DTM, and document source, resolution, date, and datum. Do not present uncorrected imagery as survey-grade evidence.
Assuming that a Bim Saviya title certificate and cadastral map are coordinate-perfect and ignoring discrepancies in the underlying survey plan and boundary marks.
Official registration creates an impression of finality, but title registration does not cure a defective survey or a misdescribed boundary.
What to do instead
Check the underlying survey plan, control, and boundary marks against the title and cadastral map. Explain that registration and boundary accuracy are separate issues and record any discrepancy before advising the client.
Rewriting or backdating field notes to make a misclosure disappear, or signing a plan without an independent check by another competent person.
Time pressure and client expectations make a clean-looking result tempting, and candidates underestimate how original notes and independent checks protect both the client and the surveyor.
What to do instead
Keep original field notes, correct errors by dated strike-through rather than replacement, document the reason for every change, and require an independent check before signing or certifying any plan.