Surveying and mapping using GPS/GLONASS systems

GENERAL PROVISIONS

This procedure specifies the process of surveying and mapping issuance at each step of the work performance.

Surveying includes all works performed using surveying instruments, tools and software.

 

FIELD WORKS

In process of field works Customer’s controlled facilities area reconnaissance shall be performed, surveying plan shall be approved by the expert team responsible manager and the scope of field works shall be performed by engineering surveying crews, as well as the required scope of calculations and other works related to preliminary processing of the obtained data and materials to assure control over their quality, completeness and accuracy.

Preparation for field surveying

While preparing for field works the surveying crew manager shall verify availability and operability of instruments, tools and software required for the crew to perform quality works.

Normally the field works are authorized to be performed by persons trained to operate instruments of the type planned to be used for work execution.

Before performing field works to assure the survey reliability trial satellite measurements are recommended to be made simulating field conditions in the following situations:

•  This type of receiver or the satellite estimation procedure is used by contractor for the first time;

• This type of receiver is used for the first time at this topography or contractor performs satellite estimations surrounded by obstacles typical for this topography for the first time;

Trial satellite measurements shall be performed using the same methods and if possible in the same conditions as at the planned work site.

Surveyor’s pickup design

Surveyor’s pickup is developed from the state geodetic network points, geodetic network bridging category 1 and 2 and technical leveling. Plane coordinates and elevations of pickup points using global navigation satellite systems are defined by survey networks construction or by hanging points method.

Limiting accuracy of the design surveyor pickup points location including design control points against the state geodetic network points shall not exceed 0.2 mm in the map or plan scale for open territory and built-up areas and 0.3 mm for a large scale survey at the trees and shrubs covered territory.

To assure the required accuracy of situation and contour survey for areas adverse to unobstructed radio signal transmission (population density, high facilities (>3 m), etc.) the surveyor’s pickup is recommended to be constructed using a tachometer.

For surveyor’s pickup design designers and other companies’ special requirements to geodetic networks shall be considered. In addition the following aspects shall be taken into account for engineering:

• To develop the surveyor’s pickup using a satellite technology, subject to the designed survey scale and contour interval, one of the two methods shall be used – network construction method or hanging points location method

• Reference points from which the surveyor’s pickup is constructed shall include all geodetic data points located within the facility and nearest ones beyond the facility but at least 4 points with known plane coordinates and at least 5 points with known elevations in order to assure the surveyor’s pickup is reduced to the geodetic data point coordinates and elevations system.  

• When high accuracy data are not required the hanging points method is recommended to be used to develop the survey geodetic data.

Surveying is allowed to be performed based on the state geodetic network with density of 1 SGN point / 5 – 15 km², should there be no factors impacting the satellite positioning accuracy.

Survey work performance

Field reconnaissance

Field reconnaissance shall be performed to identify visually the location and purpose of underground installations and to detect pipeline segments using line locators. In process of reconnaissance the following should be done:

• Geodetic data points shall be inspected and their actual applicability for satellite surveillance shall be identified.  If the number of satellites applicable for surveillance over geodetic data points is limited actions assuring surveying possibility at these points (receiver antenna jacking, antenna installation point location including identification of reduction elements) should be developed.  

• The most critical and typical points of the surveyed facility, such as, the pipeline segment start and end points, other pipelines tie-ins, block valves, industrial facilities (BS, GMS, WDM, etc.) are found and positioned.

• To improve efficiency of technical diagnostics and survey works of the facilities under inspection the reconnaissance shall include selection of access roads to the inspected facilities, consideration of vegetation height and search for obstacle bypasses in the future works area.

• Different geodetic and mapping information on the territory under inspection is collected. Following reconnaissance an inspected facility plot is prepared by marking typical points of this facility on the base material and diagnostics plan is developed. 

Mainline underground and aboveground structures survey

In process of underground and aboveground structures survey the following elements and technical parameters shall be identified:

•  For water lines pipe outer diameter; purpose (utility and drinking water, service water);

•  For sewage pipes system parameters (force main, gravity sewer); purpose (domestic, industrial, runoff); pipe diameter (internal for gravity sewers and external for force mains);

•  For heating installation type (trench or trenchless); trench type (accessible, creep, non-accessible); trench material and internal dimensions; number and external diameter of pipes;

• For gas and oil pipelines pipe external diameter.

• For cabling electric cable voltage (high voltage 6 kV or higher, low voltage); direction (transformer substation numbers if available) for high voltage cables; installation conditions ( sewage, manifolds, armoured cable); communications cable identity if available; number of holes in the telephone conduit; material and dimensions of distribution points, transformer substations, phone cabinets and boxes.

Location of deflection points and other underground structures hidden points and their depths shall be detected using line and cable locators, if they cannot be used pitting is performed.

Pipe laying depth identification using line and cable locators shall be performed twice. The measurement results discrepancy shall not exceed 20%.

The distance from the base to the farthest survey point shall not exceed 30 m (if it is not possible to install the base at this distance the measurement at the points shall be increased proportionally to the increased distance).

Fixing (coordinating) bases to SGN points

Bases location identified in process of reconnaissance are fixed to the nearest SGN points. Fixing shall be performed in favorable time (i.e., the number of satellites shall be more than 6, PDOP shall not exceed 4) identified using “freshly downloaded” ephemerides in Pathfinder Office, module Quick Plan or in Trimble Geomatics Office, module Planning. Prior to going to the field all equipment and battery charge shall be checked, the observation period at the points shall be planned per specific time.

Situation and contour survey performed by satellite measurement

Topographic surveying normally should be performed in a favorable time of the year. Survey performance is allowed at snow cover height not exceeding 10 cm. Topographic plans developed based on the data from the survey performed at snow cover height not exceeding 10 cm shall be updated within the favorable time of the year. Based on the rated survey scale and contour interval:

• The survey shall be performed in line with Guidelines for topographic surveying, scales 1:500, 1:1000, 1:2000, 1:5000".

• During the survey in each area the base station reception shall continue throughout the whole time of mobile station work execution in this area.

• While surveying loaded areas such as: block valves, interchanges, power line crossings, BS areas, CPF and other facilities a detailed territory outline shall be developed.

Survey work contents

Based on the topographic survey purpose satellite measurements are performed during field works to identify relative position of individual ground points. Situation survey includes identification of plane coordinates of points belonging to structures and ground elements (contours) boundaries. Identification of coordinates and elevations of points describing contour is included in the contour survey.

The main objective of situation survey is identifying relative position of required and sufficient number of typical contour points to assure contour mapping on the plan per survey accuracy and details requirements of the scale specified by Customer. In addition the survey completeness shall meet requirements of effective symbols (*).

The survey subjects depending on the tasks in hand, the developed plan purpose and scale, degree of development include:

a). all populated areas without exception regardless of their size with all individual buildings plotted in the scale of 1:2000 or larger irrespective of their location conditions, annexes hereof shall be displayed;

b). all types and purposes above ground installations – industrial, cultural, general, improvement; all transport and pedestrian connection categories without exception including all types of structures thereof, historical monuments, parks, planting in the streets and squares, underground utilities exit points;

c). Individual buildings outside of populated areas irrespective of their purpose and size;

d). irrigated and drainage plots including operating and other structures;

e). all types of natural and artificial water bodies and water sources split into permanent and  intermittent ones and all structures thereof specifying their configuration and operating parameters;

f). isolated trees, bushes, rocks and shrubbery in the open terrain; forest areas identifying conifer, foliage species and mixed forests, felled areas, burned areas, glades and wetlands identifying wood species, average height and thickness at 1.5 m over ground;

g). agricultural land plots split into types: greenhouses, orchards, grape nurseries, gardens, lay-lands, hay-lands, flood meadows, steppes, etc.;

h). layouts of non-agricultural land plots: rocky areas, sands, passable and impassable bogs, etc.;

i). ore minerals and rock products mining areas;

j). boundaries and boundary posts available in the area: city limits, railway, road, oil and gas pipeline right-of-ways, etc..

Based on the building material, engineering structures purpose and outline shapes nature all terrain elements are divided into two types:

• Distinct contours,

• Indistinct contours.

Distinct contours include permanent engineering structures constructed from long-term fireproof materials (bricks, concrete, etc.).

Indistinct contours include temporary structures, permanent structures constructed from light non-permanent non-fireproof materials (bulrush, wood, etc.) and natural outlines. Natural outlines are additionally subdivided into sharp outlines, i.e., having clear identifiable boundaries, and unsharp outlines, i.e., not having clear boundaries.

Such division is kind of conditional and in certain cases does not assure unambiguous solution.

For situation survey accuracy of measurements and points plotting is defined both by survey scale and by outline shapes nature.

For example, for built-up areas (with permanent structures) the highest measurements accuracy is required, dimensional in particular. Average line measurement error shall not exceed 0.2 mm in the survey scale which allows assuring average error not exceeding 0.4 mm for relative position of adjacent lines on the plot.

For survey of sharp outlines the survey errors shall be such that average error of points plotting vs. surveyor’s pickup points does not exceed 2.0 m in the scale of 1:5000; 1 m in the scale of 1:2000; 0.5 m in the scale of 1:1000; 0.25 m in the scale of 1:500.

The number of points for sharp outlines situation survey shall be selected so that two adjacent outline points may be joined by a line and the outline actual curve does not deviate from this line by more than 0.5 mm on the plot.

Individual outlines bulges and bends having a size not exceeding 1.0 m for survey in the scale of 1:5000; 0.50 m for survey in the scale of 1:2000 and 0.3 m for survey in the scale of 1:1000 may be rectified.

For survey of unsharp outlines an error of up to 5 m is acceptable irrespective of the survey scale. Outlines without clear boundaries (open forest, shrubs in the meadow, etc.) are outlined and surveyed approximately.

Small outlines, less than 0.1cm² in the survey scale, and individual area features not stated dimensionally in the survey scale are not outlined during the survey but are surveyed as one point selected in the center of the surveyed outline or area feature. To plot buildings with incorrect shape all corners are surveyed. Survey of regular geometric shape buildings is performed by combining corners survey with ruler measurements. For transport routes irrespective their width all buildings and structures, road bends start and end, track centerlines, embankments, excavations, water ditches are surveyed specifying the width of the complete road, traffic way, embankment, roadsides, width and depth of excavations and ditches, road routes. Field and country dirt roads are surveyed only axially specifying the width. Water bodies (if their width exceeds 3 mm in the survey scale) are surveyed in any scale on both sides, rack points shall be selected at the same normal line as the water body axis, if the water body width is between 1 and 3 mm – on one side; the water body width shall be defined by measurements and recorded in the log. In parallel with surveying water bodies all waterside structures are surveyed.

For unbuilt areas all overhead lines are surveyed; in the scale of 1:2000-1:500 all poles are surveyed; in the scale of 1:5000 — only angle poles, if survey of all poles is not specified in the task order.

Contour survey is based on the assumption that contour on topographic maps is represented as contour lines which key sections are set between 0.5 and 5.0 m.  For the best expression of contours in the indicative areas of peaks, basins, saddles, slope gradients change, etc. auxiliary or approximate contours are constructed. To construct contours on the plot during the survey a certain number of points is selected to the effect that the contour is reflected in the best way with the minimum number of selected points. The following considerations are used as guidelines.

Points for surveying an area with clearly defined contour and regular slopes are selected at distances not exceeding the values specified in Table 1. 

Table 1

Survey scale	Contour intervals, m	Maximum distance between survey points, m
1:500	0,5	10
1:1000	0,5	20
	1	30
1:2000	0,5	40
	1	50
	2	60
1:5000	0,5	60
	1	80
	2	100
	5	120

For areas with undefined contours and variable slopes the number of points shall be increased. However it shall be taken into account the excessive number of points complicates contour construction. Thus, prior to survey the area needs to be inspected and survey point locations need to be identified.

Vertical points shall be taken at peaks, master lines, slope discontinuities, at the foot of the hills, saddle discontinuities, talwegs at their turns, tops and bottoms of hollows, ditches, pits, cones and their edges, river and stream sides, water edges and other areas required to construct the contour.   The points shall be selected so that they represent not only area elevations, but also show direction of slopes and so that slopes between these points may be considered regular.

In addition to points selected for contour construction points of engineering structure foundations and apexes, dams, bridges, embankment tops and bases, road axes and intersections, tops of mounds, rail heads, next to wells, near structures and in the most typical areas shall be identified. Elevations taken from local features or outlines that are not recommended to be used for contour construction shall have a proper mark. Trenched or rocky areas, sand deposits shall be outlined determining their points not less than as specified in Table 1.

Field works during surveying shall be combined with in-house processing of the survey data which shall include the following:

• a detailed location drawing development;

•  calculation of all points coordinates and elevations.

The field works shall be concluded by computer processing of satellite observations data. 

Computer processing is performed in Pathfinder Office. The final processing results shall be in a corrected file format (*.cor) where all survey points and lines are corrected to the specified accuracy (3D differential) and verified for codes and attributes compliance.

Control of measurements made with geodetic satellite equipment

Control is assured using equipment which accuracy class is higher (in our case a tachometer or phase detection receivers are used). Deviation shall not exceed the tolerance. The control is random (in accessible areas).  

Diagnostics and surveying combination

Prior to underground structures diagnostics they shall be located using line locators and tied using surveyor’s stakes. Stakes are made of materials at hand, marked with signal tape and signed (pipe depth, kilometer point registered in the product flow direction).   

The right-of-way is staked at intervals as specified in the task order issued by Customer.

Prior to locating and geodetic works performance NDT engineers and surveyors develop an interface plan and have it approved by the responsible manager.

The plan describes crews staffing, locating methods, distances at which the kilometrage shall be staked (i.e., stakes to be double filleted with signal tape and signed with different colour), use of other symbols and interface methods.

Prior to the facility surveying all diagnostics works shall be completed, i.e. all trenches shall be marked with special signal tapes, the stakes shall specify the number of trench and actual pipe depth. All areas with coating defects identified in process of ANPI operation and potentially hazardous sections shall be also marked with special signal tape and numbered.

REPORTING DATA PREPARATION FOLLOWING FIELD WORKS

Reporting data development and contents

A soft copy of field data shall be submitted weekly to the in-house department (by e-mail).

The weekly report shall include data about the type and scope of works performed and shall be a document including text and attached graphics file (-s).

The text file shall include information about the facility description and inventory number (or the number per updated diagnostics work schedule) and information about the scope of work performed.

Comments to the works performed at each facility or part hereof shall include:

•  title of the pipeline starting and end points, tank or other facility.

•  Information about numbers and descriptions of valves and any other facilities reflected in the work.

The attached graphics file including results of surveying or any other inspections shall be updated, translated into the local coordinates and created using “symbols and codes library”.

For the pipeline surveying the information on depth at each point under survey shall be available.

Any mainline facility is allowed to be submitted in sections (for pipeline surveying or locating).

Reporting data submission procedure

Weekly field survey works report shall be submitted to the diagnostics company central office. An exception is when a crew is in a long lasting expedition. In this case a delay in the report submission is allowed by the timeline to return from the expedition given the time required to process the survey results.  

Within three days the weekly report received by the in-house department shall be either accepted or returned specifying its objective deficiencies. In such a case the surveying crew shall rectify the detected deficiencies within one week and send the revised report back to Moscow office.

IT IS NOT ALLOWD:

•  To submit results (final or preliminary) in a false grid system.

• To work with a controller without “symbols and codes library”.

• To submit works not stating the facilities titles.

Note: work without “symbols and codes library” is allowed only as an exception, such as internal information failure in the controller during a long expedition.

 

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