All instruments that have a resection application may have manufacturer specific algorithms to calculate the final position of the resection. It is important to verify that the software algorithm is in fact a resection calculation, not a modified triangulation calculation. In order to ensure that at least one resection can be calculated from the observations, it is required that at least three known sidewall stations should be observed. All observations must provide sufficient redundancy in order to calculate the final position of the resection point, preferably using a least squares method of calculation. It is important that the software must provide a logical printout template of observations and position fix.
It is important that any calculation made in real-time on the instrument and at a later stage in the office must be in a format that can be easily interpreted and then stored and printed for future reference. There is a tendency to neglect the importance of maintaining proper records of observations and calculations in favour of trusting the software to recalculate any set of observations made. This view does not take into account that data formats can change and if not kept up to date may mean that recalculation could prove impossible at a future point in the life of mine. The current regulations on Mine Surveying stipulated by the MHSA do not require the maintenance of records. [17]. The following hazards were identified in the calculation phase of establishing a survey network:
Table . Risk analysis for the calculation phase of installing sidewall stations
Risk
|
Hazard
|
Contributing factors
|
Mitigating Actions
|
Inaccurate determination of survey control
Deterioration of survey network
Survey deemed inaccurate by DMR leading to check survey to be conducted on mine’s cost
|
Off-line mining
Unplanned breakthroughs
Misalignment of connections
Mining boundary position, regional pillars compromised
Deterioration of survey network
Survey accuracy exceeds MHSA standard of accuracy
Calculation methodology based on poor mathematical principles
Loss of trust in surveyor and survey method
|
Poor observation protocol
Incorrect reference survey stations s used
Inaccurate co-ordinates used for reference
Instrument calibration
Instrument settings
Inadequate redundancy in observations
Incorrect observations not removed from the calculation
|
Observe correct observation protocol
Ensure correct orientation
Ensure integrity of survey stations through check surveys
Check calibration and settings
Use correct prisms
Set specific instrument tolerances
|
Data corrupted
|
Data lost before transfer from instrument
Data edited fraudulently
Data edited unintentionally
Instrument recording template damaged
|
Incorrect downloading procedures
Download template damaged
|
Enforce download protocol
Download data as soon as possible
Create a backup immediately
Conduct data integrity audits
|
Incomplete or no records of calculations
|
Calculation software does not provide a clearly defined template of essential survey information
|
Software template insufficient or not available
|
Develop template to show required information
Print hardcopies
Backup electronic record
|
[159]
8.8. Phase 5. Storage and presentation
The fifth phase of the process covers the record keeping, presentation and storage of data. In older versions of the MHSA the process of record keeping was prescribed. In the latest version of the regulations, considered to be an outcomes based Act rather than a regulatory Act, the regulations surrounding the storage and presentation of survey records have been removed. During the research conducted on sidewall survey stations it became clear that insufficient records on the fixing of resection points were kept in most cases, making a recalculation from original observations of a check survey impossible.
The presentation of data has three basic outputs, namely co-ordinates, a “void model” of measured profiles and the alignment of current layouts with the mine design. The following generic risks with reference to the storage and presentation of data were identified:
Table . Risk analysis of the presentation phase of installing sidewall stations
Risk
|
Hazard
|
Contributing factors
|
Mitigating Actions
|
Data corrupted
|
Data lost before transfer from instrument
Data edited fraudulently
Data edited unintentionally
Instrument recording template damaged
|
Incorrect downloading procedures
Download template damaged
|
Enforce download protocol
Download data as soon as possible
Create a backup immediately
Conduct data integrity audits
Store data off site on external storage devices
|
Incomplete or no records of calculations
|
Calculation software does not provide a clearly defined template of essential survey information
Data not available for survey network, mine design
Survey data on network damaged or lost
|
Software template insufficient or not available
|
Develop template to show required information
Print hardcopies
Backup electronic record
|
Data storage outdated making data access impossible
|
Software updates
Data can be corrupted through multiple transfers
Instrument or software changes can make old data inaccessible
|
Software updates are a regular occurrence
Change of equipment due to cost or other factors
|
Maintain all data in the most common type of data format
Keep hard copies of all essential control networks and check surveys
Maintain an up to date hardcopy of the peg register
|
[159]
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