Surveying Fundamentals (Kavanagh)

Definition: Systematic Error

An error for which the magnitude and algebraic sign can be determined. Examples: temperature effects on tape, erroneous tape length. Can be calculated and corrected. — Kavanagh Ch. 1, p. 13

Definition: Random Error (Accidental Error)

Errors introduced because no human can perform perfectly. Two key characteristics: (1) magnitude is unknown, (2) they tend to cancel out over the long run. — Kavanagh Ch. 1, p. 13-14

Definition: Mistake (Blunder)

Blunders made by survey personnel. Examples: transposing figures (86 for 68), miscounting tape lengths, measuring to wrong point. Must be discovered and eliminated through verification. — Kavanagh Ch. 1, p. 15

Why can sloppy work appear accurate?

Large random errors tend to cancel out, giving the appearance of accurate work even when highly inaccurate. This is why proper techniques and specifications are essential. — Kavanagh Ch. 1, p. 14

Definition: Accuracy

The relationship between the value of a measurement and the 'true' value of the dimension being measured. Greater accuracy = smaller error. — Kavanagh Ch. 1, p. 14

Definition: Precision

The degree of refinement with which a measurement is made. Higher precision = more repeatable results, tighter grouping. — Kavanagh Ch. 1, p. 14

Accuracy Ratio Formula

Accuracy Ratio = Error of Closure / Distance Measured Expressed as a fraction with numerator of 1 and denominator rounded to closest 100 units. Example: 0.05 / 196.28 = 1/3,926 ≈ 1/3,900 — Kavanagh Ch. 1, p. 15

Common accuracy ratio specifications

• Engineering surveys: 1/3,000 to 1/10,000 • Property surveys: 1/5,000 to 1/7,500 • High-cost urban: 1/10,000 or higher • Ditched highway: 1/3,000 • Monorail transit: 1/7,500 to 1/10,000 — Kavanagh Ch. 1, p. 15

Plane Survey vs. Geodetic Survey

Plane Survey: Ignores Earth's curvature for horizontal dimensions. Used for most engineering projects. Geodetic Survey: Accounts for Earth's curved (ellipsoidal) shape. Required for large geographic areas. — Kavanagh Ch. 1, p. 2-3

Control Survey

Establishes reference points (benchmarks) and reference lines for preliminary and construction surveys. Provides the horizontal and vertical datum for other survey work. — Kavanagh Ch. 1, p. 4

Preliminary Survey vs. Layout Survey

Preliminary (preengineering): Collects measurements to locate natural and built features for plans. Layout (construction): Uses dimensions from design plans to locate proposed works in the field. — Kavanagh Ch. 1, p. 4

Field Notes: Handling measured data mistakes

Mistakes in measured data entries must be carefully LINED OUT, not erased. This preserves the integrity of the field record. Mistakes in other entries (descriptions, calculations) may be erased and reentered. — Kavanagh Ch. 1, p. 16

Field Notes: Verification procedure

Note keepers verify all given data by repeating the data ALOUD as they enter it. The surveyor who gave the data listens and responds to confirm. — Kavanagh Ch. 1, p. 16

Four methods of locating a point

1. Rectangular tie-in (right-angle offset) 2. Polar tie-in (angle and distance) 3. Intersection tie-in (angles or arcs from two points) 4. Positioning tie-in (GPS, remote sensing) — Kavanagh Ch. 1, p. 4-5

International Foot Definition (since 1959)

1 foot = 0.3048 meters (exactly) 1 inch = 25.4 mm (exactly) Prior to 1959, U.S. Survey foot = 0.3048006 m — Kavanagh Ch. 1, Table 1.1, p. 12

Stationing (Chainage) System

0+00 = starting point 1+00 = 100 ft from start 1+56.73 = 156.73 ft from start Full stations at 100-ft (or 100-m) intervals. — Kavanagh Ch. 1, p. 11

Earth curvature divergence values

Divergence between level line and horizontal line: • At 1,000 ft: 0.024 ft • At 300 ft: 0.002 ft • At 100 m: 0.0008 m — Kavanagh Ch. 2, p. 20