ENEV 281 - Chapter 4 - Measuring Horizontal Distances Flashcards

Practice flashcards covering Chapter 4: Measuring Horizontal Distances, including pacing, taping, stationing, and Electronic Distance Measurement (EDM).

Pacing

A method of rough distance measurement with an accuracy of about $1:100$ that involves counting steps while walking naturally along a line.

Unit pace

The distance between left and right toes or heels, used to calculate distance via the formula: Distance = unit pace $\times$ number of paces.

Measuring Wheel

A tool used for rough distance measurements that helps reduce counting mistakes and is good for curved lines, with a typical accuracy of $1:200$.

Relative Accuracy (Taping)

The generally accepted range for most preliminary and ordinary property surveys, falling between $1:3000$ and $1:5000$.

Gunter’s chain

An original surveying tool with a length of $4$ rods or $66\,ft$ ($20\,m$) subdivided into $100$ wire links.

Steel Tapes

Measuring tools most commonly found in lengths of $100\,ft$ or $30\,m$, graduated throughout in feet/tenths/hundredths or meters/centimeters/millimeters.

Cut Tapes

Older tapes marked every foot, with only the first and last foot intervals graduated, requiring mental subtraction to determine a distance.

Add Tapes

Tapes with graduations extending $0.99\,ft$ beyond the zero mark, requiring the decimal fraction to be added to the foot interval reading.

Plumb bob

A surveying accessory used to transfer a position from a steel tape held above the ground to a specific point on a wooden stake or surface.

Hand level

An accessory used to ensure the tape is held in a horizontal position when taping over uneven ground.

Tension handle

An accessory used to ensure the correct amount of pull is applied to a steel tape during measurement.

Clamp handle

A device used to provide a firm grip on a steel tape at any point along its length without damaging the tape.

Breaking Tape

The process of measuring horizontal distance in short increments when the ground is too steeply sloping to use a single full tape length.

Stationing

A method of specifying distance to a position along a linear corridor survey, such as a road, path, or pipeline.

Station 0+000

A notation representing the start position of a survey when using kilometers as the stationing unit.

Station 4+356

A notation representing a distance of $4356\,m$ ($4\,km$ plus $356\,m$) along a survey alignment from the beginning.

Taping Blunders

Serious mistakes such as misreading the tape, misrecording readings, miscounting full tape lengths, or mistaking station markers.

Systematic Errors (Taping)

Predictable errors that can be corrected, including tape length variations, temperature changes, and sag.

Accidental Errors (Taping)

Errors occurring when the tape is misaligned or off-level, which should be within $1\,ft/100\,ft$ ($0.3\,m/100\,m$) for good accuracy.

Sag

The natural tendency of a steel tape to curve downward between supports, which occurs regardless of how hard the tape is pulled.

Standardization Temperature ($T_s$)

The specific temperature at which a steel tape is calibrated to its true length, typically $20^\circ C$.

Coefficient of Thermal Expansion (Metric) ($\beta$)

The value used in temperature correction calculations for steel tapes in metric units, equal to $1.16 \times 10^{-5}$.

Coefficient of Thermal Expansion (US) ($\beta$)

The value used in temperature correction calculations for steel tapes in US units, equal to $6.5 \times 10^{-6}$.

Temperature Correction Formula ($C_t$)

The formula $C_t = \beta D (T - T_s)$, where $D$ is the distance, $T$ is the tape temperature, and $T_s$ is the standard temperature.

Electronic Distance Measurement (EDM)

A measurement method using electromagnetic waves, such as infrared light, which offers increased speed and accuracy for long horizontal distances.

Electronic Total Station

A modern surveying device, also known as an electronic tacheometer instrument (ETI), used for electronic distance measurement.

Reflecting Prisms

Accessories used with EDMIs to reflect beams of light back to the instrument in a direction parallel to the original beam.

Hub

A wooden stake driven into the ground at a station to mark its location.

Tack

A metal marker set on the top of a wooden hub to provide a precise point for distance and alignment measurement.

Significant Figures (Pacing)

The rule stating that paced distances should be rounded to no more than three significant figures.