Spatial positioning of sidewall stations in a narrow tunnel environment: a safe alternative to traditional mine survey practice

Phase 4. Calculation methodology

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

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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

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