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Questions and Answers
What should be the distance within which 2nd and 3rd Order geodetic control stations are absent from the project boundary?
What should be the distance within which 2nd and 3rd Order geodetic control stations are absent from the project boundary?
- 20km
- 15km
- 5km
- 10km (correct)
Which survey symbol is used for a Free Patent Application?
Which survey symbol is used for a Free Patent Application?
- G
- H
- F (correct)
- A
Which type of geodetic control points should be used in the design of a Control Network?
Which type of geodetic control points should be used in the design of a Control Network?
- Only recently established points
- Only stable or undisturbed points (correct)
- Only points from recent surveys
- Any points within the project area
What does the symbol 'Tsa' represent in public land surveys?
What does the symbol 'Tsa' represent in public land surveys?
What is the maximum distance between 1st order control points in a Primary Geodetic Network?
What is the maximum distance between 1st order control points in a Primary Geodetic Network?
Which of the following survey symbols signifies a Lease Application for an Agricultural Individual?
Which of the following survey symbols signifies a Lease Application for an Agricultural Individual?
What does the abbreviation 'Gss' stand for in the context of survey symbols?
What does the abbreviation 'Gss' stand for in the context of survey symbols?
Which of the following is NOT required to be notified in writing before conducting a survey?
Which of the following is NOT required to be notified in writing before conducting a survey?
What is a characteristic of the network design for GNSS observations?
What is a characteristic of the network design for GNSS observations?
Which symbol represents an Agricultural Colony in public land surveys?
Which symbol represents an Agricultural Colony in public land surveys?
In designing a network of controls, how many GNSS receivers are considered sufficient?
In designing a network of controls, how many GNSS receivers are considered sufficient?
The symbol 'Mli' in land surveys refers to which type of application?
The symbol 'Mli' in land surveys refers to which type of application?
What is the purpose of using closed polygons in network design?
What is the purpose of using closed polygons in network design?
Which survey symbol corresponds to a Miscellaneous Sales Application by Charitable Institution and Corporation?
Which survey symbol corresponds to a Miscellaneous Sales Application by Charitable Institution and Corporation?
Which order of control points should have a maximum distance of 2 km between pairs?
Which order of control points should have a maximum distance of 2 km between pairs?
Which factor is NOT relevant for network design considerations?
Which factor is NOT relevant for network design considerations?
What is the minimum number of known PRS 92 control points required in the designed Network?
What is the minimum number of known PRS 92 control points required in the designed Network?
Why should field observations be timed when the Position Dilution of Precision (PDOP) is low?
Why should field observations be timed when the Position Dilution of Precision (PDOP) is low?
Which factor is NOT considered during the reconnaissance process when determining control points?
Which factor is NOT considered during the reconnaissance process when determining control points?
What are the latitude coordinates of Balanacan station?
What are the latitude coordinates of Balanacan station?
What feature describes the station mark at Balanacan?
What feature describes the station mark at Balanacan?
What is the primary purpose of conducting reconnaissance in the area?
What is the primary purpose of conducting reconnaissance in the area?
Who established the Balanacan station?
Who established the Balanacan station?
Which of the following dimensions corresponds to the First Order Accuracy control monument?
Which of the following dimensions corresponds to the First Order Accuracy control monument?
What aspect of the travel time estimation is necessary for the survey team during reconnaissance?
What aspect of the travel time estimation is necessary for the survey team during reconnaissance?
What is the depth of the hole at the station mark in Balanacan?
What is the depth of the hole at the station mark in Balanacan?
How is a geodetic station defined to be in the Luzon Datum?
How is a geodetic station defined to be in the Luzon Datum?
Which of the following best describes the standard dimensions for a Third Order Accuracy control monument?
Which of the following best describes the standard dimensions for a Third Order Accuracy control monument?
What type of obstructions are surveyed during reconnaissance that may disrupt data transmission?
What type of obstructions are surveyed during reconnaissance that may disrupt data transmission?
What was the purpose of the Philippine Geodetic Network (PGN)?
What was the purpose of the Philippine Geodetic Network (PGN)?
What type of triangulation was predominantly used in the PGN?
What type of triangulation was predominantly used in the PGN?
Where were the triangulation stations of the PGN mainly concentrated?
Where were the triangulation stations of the PGN mainly concentrated?
What does a low GDOP value indicate during a GNSS session?
What does a low GDOP value indicate during a GNSS session?
What minimum number of observations is required to achieve 1st Order accuracy?
What minimum number of observations is required to achieve 1st Order accuracy?
Which of the following actions should be avoided within 10 meters of a GPS receiver?
Which of the following actions should be avoided within 10 meters of a GPS receiver?
What is the recommended number of observations for achieving 2nd Order accuracy?
What is the recommended number of observations for achieving 2nd Order accuracy?
What is a potential consequence of not downloading stored data from the receiver promptly?
What is a potential consequence of not downloading stored data from the receiver promptly?
What does PDOP stand for?
What does PDOP stand for?
How long does it take to retrieve data from a satellite when 6 or more satellites are used?
How long does it take to retrieve data from a satellite when 6 or more satellites are used?
What is the effect of using older Geodetic Control Points in network design?
What is the effect of using older Geodetic Control Points in network design?
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Study Notes
Project Control Accuracy Specifications & Survey Symbols
- In the absence of 2nd and 3rd order geodetic control stations within 10km of the project boundary, connect to an LMB-certified reference point.
- Survey symbols (DMC 2010-13 Annex I) define land use types (e.g., Reclaimed Land Lease Application (Rlla), Agricultural Colony (Ac), Lease Applications, etc.). Refer to the provided text for a complete list.
- Balanacan Station (Luzon Datum of 1911): Latitude 13° 33‘ 41.000“ N, Longitude 121° 52‘ 03.000“ E. Marker is a hole (1.5cm diameter, 6cm deep) in a triangle (16cm sides) in hard rock.
- Luzon Datum 1911 stations established by O.W. Ferguson and H.D. King; connected by continuous triangulation from Balanacan Station. The Philippine Geodetic Network (PGN), developed until 1946, comprised coastal 2nd order triangulation stations. Only stable control points are usable.
- Before surveying, notify: Provincial Engineer, PENRO, DPWH District Engineer, CENRO, Municipal Engineer, Head of Field Office, Barangay Chairman, and Lot owner/claimant.
- Surveys begin and end at established PRS 92 control points for checks. Baseline lengths for different orders of accuracy are specified (e.g., 1st order - 50km; 2nd order - 25km; 3rd order - 5km; 4th order - variable, but each barangay needs at least one pair within 2km).
Network Design & Reconnaissance
- Inter-visibility isn't crucial for GNSS; select stable, accessible points unaffected by future construction; avoid swampy areas.
- Network design considers terrain, available geodetic controls, number of GNSS receivers (3+ sufficient), and observation length/type. See Section 25 for details.
- The network should form closed polygons (triangles preferred) with at least three known PRS 92 control points for each station; include redundancy. Conduct observations with low PDOP (Position Dilution of Precision) for better accuracy.
- Reconnaissance determines accessibility, ground stability, routes, radio tower proximity (obstructions above 15°), travel time between stations, number/status of old control points, and required property permissions.
Geodetic Control Monuments & Connections
- Monument dimensions vary by accuracy order (First-Fourth Order). Specifications are given for top and bottom cross-section sizes and lengths above/below ground. Sizes are given in centimeters.
- Minimum and recommended observation numbers for connecting to existing controls of the same or higher order are: 1st order (3 min, 4+ rec), 2nd order (2 min, 3+ rec), 3rd order (2 min, 2 rec).
Observations & Old Control Points
- During GNSS sessions, monitor GDOP (Geometric Dilution of Precision); lower GDOP is better. Download data promptly, manage receiver memory to avoid overloads, and avoid electronic devices within 10 meters of the receiver.
- Include old geodetic control points in the network design (Sections 6, 11, and 12).
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