Primer — What is land surveying?
The hook
Before GNSS, before total stations, before any of this was electronic — surveyors built the country with a chain, a compass, and a transit. This topic tests whether you understand the vocabulary and basic mechanics that everything else builds on. Horizontal surveying for position, vertical for elevation, route surveying for alignments — and one nasty bit of geomagnetism called declination.
Memorize these
Concepts that show up on the exam
Horizontal survey
Determines the position of points in plan view (X/Y or E/N). Outputs traverses, coordinates, areas.
Vertical survey
Determines elevations. Outputs benchmarks, contours, profiles. Independent of horizontal in most workflows.
Route survey
Surveys along a linear corridor (highway, pipeline, transmission line). Combines alignment, profile, and cross-sections.
Magnetic declination
The horizontal angle between true (geographic) north and magnetic north at a location. Easterly when magnetic N is east of true N; westerly when west.
Annual change
Declination drifts 5–10 arcminutes/year in most of the U.S. NOAA publishes current values and rates.
Compass bearing
A direction read off a magnetic compass. Always referenced to magnetic north — convert with declination to get true bearing.
Keep these in muscle memory
Formulas to know cold
True bearing from magnetic
true = magnetic + east_declinationGoing magnetic → true: ADD easterly declination, SUBTRACT westerly. (Reverse the signs going true → magnetic.)
Updating an old bearing for current declination
true_today = compass + decl_todayTry it before you peek
Worked example
The problem
An 1885 deed describes a property line as bearing N 38° 30' E by compass. The declination at the survey location at that time was 4° 30' W. The current declination is 8° 15' W. What is the current MAGNETIC compass bearing for the same line?
Don't fall for these
What trips people up
Easterly vs. westerly declination signs
Easterly declination is positive (added to magnetic to get true). Westerly is negative. Reverse for going true→magnetic. Get this backward and your answer is off by 2× the declination.
Old deed bearings are NOT today's magnetic bearings
An 1850s deed bearing was correct on the day it was written, but reading it with today's compass will be off by a degree or more. Convert through true.
Magnetic declination ≠ magnetic deviation
Declination is the difference between true N and magnetic N at a location. Deviation is the error of an individual instrument (caused by nearby iron, etc.). Different problems, different corrections.
Test yourself
How well did it stick?
A quick 5-question check on Basic Surveying. See where you stand and what to review.