Survey Beacons and Location Techniques

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Questions and Answers

What is the maximum allowed azimuth closure at azimuth check points per station?

1' 30"

2' 0" (correct)

1' 0"

3' 15"

Which measurement procedure is typically used for vertical control in survey settings?

Triangulation

Using GPS

Geodetic leveling (correct)

Pacing

What weight is given to the standard error of the mean for azimuth observations?

+1.0"

+0.60" (correct)

+3.0"

+2.0"

For second order traverse stations, which leveling method is recommended?

Second order class II spirit leveling Signup and view all the answers

What is the formula used to calculate the accuracy of elevation difference between two benchmarks?

i/q = tl/L Signup and view all the answers

What is the range of spread recommended for azimuth observations during control surveys?

Not greater than 3.0" Signup and view all the answers

How many measurements of azimuth should be taken across different nights?

6 observations Signup and view all the answers

What does the inter-benchmark distance (L) influence in the accuracy calculation?

Standard error of elevation difference Signup and view all the answers

What is one of the primary purposes of conducting country-wide surveys in Nigeria?

To support the conduct of public and private business Signup and view all the answers

Which of the following was a reason for the Nigerian government to publish regulations and specifications for surveys?

To provide information on expected accuracy levels Signup and view all the answers

What is indicated as one of the applications for surveys mentioned in the content?

For planning the development of urban areas Signup and view all the answers

Which chapter provides an introduction to the general purpose of conducting surveys in Nigeria?

Chapter 1 Signup and view all the answers

What standard is highlighted in the provided list of tables as related to accuracy?

National Horizontal Control Accuracy Standard Signup and view all the answers

For which of the following is the reason for surveying NOT mentioned?

Enhancement of public health Signup and view all the answers

What is the significance of establishing administrative and international boundaries through surveying?

To manage disputes effectively Signup and view all the answers

What aspect of surveys is reinforced by the government's publication of regulations?

Consolidating surveying practices Signup and view all the answers

What is a key requirement for the location of survey beacons?

They must be placed on solid ground or a stable base. Signup and view all the answers

Which type of surveys are third class beacons (Type B331) primarily used for?

Secondary and tertiary GPS, traverse, and triangulation surveys. Signup and view all the answers

How should the beacons in a network be connected?

All adjacent pairs of stations should preferably be connected by direct stage. Signup and view all the answers

What is indicated by 'D' in the strength of a triangulation figure?

Number of observed directions. Signup and view all the answers

Which of the following describes a Distance Angle in geodetics?

The angle opposite the side through which the distance is propagated. Signup and view all the answers

What is suggested about beacons in terms of their construction and quality?

Special attention should be paid to construction, quality, and preservation. Signup and view all the answers

What factor contributes to the strength of a triangulation figure?

The angles and directions observed in the triangulation. Signup and view all the answers

What is the implication of observing directions in triangulation?

It helps in determining the fixed angle opposite to a known side. Signup and view all the answers

Which theodolite is recommended for latitude and longitude determination in first order surveys?

Wild T4 Signup and view all the answers

What is the maximum permissible collimation error before servicing is required for theodolites?

15" Signup and view all the answers

What is the appropriate target marking for precision in surveying?

Targets with a clearly defined center Signup and view all the answers

How often should EDM instruments be calibrated according to the guidelines?

Annually Signup and view all the answers

What is the maximum cut-off angle for data points in satellite passes?

7.5 degrees Signup and view all the answers

Which type of targets should be avoided for optimal accuracy in surveying?

Targets that are not marked Signup and view all the answers

What should be done if the rejected satellite counts exceed a certain threshold during data inspection?

Reject the observations Signup and view all the answers

Which is NOT a recommended theodolite for Second Order (Class II) surveys?

DKM 3A Signup and view all the answers

What should be done regularly to EDM devices and reflectors?

They should be serviced regularly and checked frequently. Signup and view all the answers

Which theodolites are specified for first and second order Trilateration controls?

Wild T3 and DKM 3/3A Signup and view all the answers

What temperature record is required for Electronic Distance Measurements?

Wet and dry bulb temperature to + 1 °C Signup and view all the answers

What type of adjustment should be carried out to check for blunders?

Minimally constrained adjustment Signup and view all the answers

What must be checked for during the algebraic sum check of misclosures?

It should be within specified limits. Signup and view all the answers

Which correction is only applied for first order leveling?

Gravity corrections Signup and view all the answers

What is required for the standard error of elevations computed with a least squares adjustment?

Proper weighting conditions must be provided. Signup and view all the answers

What types of constants should be applied to measured EDM distances?

Instrument constant, reflector constant, slope correction, and sea level correction Signup and view all the answers

Study Notes

Survey Beacons

Survey beacons are essential and valuable for all survey work.
Special attention should be paid to construction, quality and preservation of beacons.
Beacons can be categorized based on their purpose and type.
Properties common to all types of beacons include location, observation procedures, and linear measurements.

Beacon Location

Beacons should be placed on stable ground like rock or solid ground.
Angles are measured using observational procedures.
Bearings are controlled by Azimuth observations.
Azimuth observations should be conducted every 12-15 stations.
Azimuth closures should not exceed 2".0 per station.
Standard error should not exceed +0".60.
Aim for spread not greater than 3".0.
Beacons should have height measurements through Class II spirit leveling.
Linear measurements are based on first order standards.

Vertical Control Accuracy

The accuracy of elevation difference between two benchmarks is calculated using accuracy (i/q).
The accuracy (i/q) is calculated by dividing the standard error (T) in millimeters by the square root of the distance (L) in kilometers between benchmarks.

Theodolites and Specifications

First order surveys use Wild T4, DKM 3A or equivalents for latitude and longitude determination.
First order surveys use Wild T3, DKM 3 or digital equivalents for directions and azimuths.
Second Order (Class I) surveys use Wild T4, DKM 3A or equivalent for latitude and longitude, and Wild T3, DKM 3 or digital equivalent for directions and azimuths.
Second Order (Class II) surveys use Wild T3, DKM3 or digital equivalents.
Third Order(Class I) surveys use Wild T2, Kern DKM 2A or DKM 2AE or equivalents.
Third Order(Class II) surveys use Wild T2, Kern DKM 2A or DKM 2AE or equivalents.

Trilateration

Wild T3, DKM 3/3A theodolites should be used for azimuth observations in first and second order Trilateration.
Wild T2 theodolites can be used for lower order Trilateration surveys.
Electronic distance measurements need a record of wet and dry bulb temperature and barometric pressure from both ends.
The closure specifications are not the same as the achieved accuracy.

Leveling

Algebraic sum check of all section's misclosures and loop misclosures should be carried out.
Gravity corrections should be applied only for first order leveling.
A minimally constrained adjustment should be carried out.
Normalized residuals should be inspected to identify potential errors.
The post adjustment estimate of variance of unit weight should be inspected to check the weight values.

Office Computation and Analysis

Correct measured EDM distances for instrument constant, reflector constant, slope correction, sea level correction and other necessary corrections.

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Description

This quiz covers the essential aspects of survey beacons, including their construction, placement, and categories. It emphasizes the significance of precise observations and accuracy in vertical control for effective surveying. Test your understanding of the protocols and standards in beacon surveying.