Visibility and not illumination Reduces mishaps
Illumination involves a source of light being emitted. To have visibility, the human eye requires illumination of light for things to be seen . Visibility is the state of being seen. To be visible you must have a level of illumination--a source of light.
Excess of illumination can result in glareUnder illumination could result in erroneous judgementProper visibility is necessary to fully identify the hazard and to judge
SizeShapeDistance If the object is moving the rate and direction And host of other factors
The saying is once bitten twice shyWe are in a similar situation so let us think before acting & not flout the norms BOOM, BANG, BEAMWe had a boom with china market &flouted normsGot a bang by a blanket ban that lead to suspension of activitiesNow we should beam with ideas to workOur Sustainability lies on compliance and not flouting the statutory norms
Working within forest area after day light hours may by itself become an issueIn the post ban era as mines restart , legal implementations are expected to become more stringent If we have legal sanction to work we need sufficient visibility for safe workingSufficient does not mean too many but judicious use of resources
It doesnt matter how many resources we have If we dont know how to use them, they will never be enoughWe may have too many lighting fixtures but if they are not properly positioned we will still have an issue
HIGH BEAM LIGHTS result in glare This will happen in over illumination .Improper utilization of resourcesThe time taken by the eyes to adjust in changed illumination levels depends upon age etc.Glare could result in fatality Driver/ on coming truck/pedestrian could be any or all
MMR 146,148Circular 3 of 197613 of 1979Circular 4 of 2009 Explains about uniformity ratio ,Glare, Lumnaires , Lumens & Lux Maintaining Lighting Plan
Legal status of Mine Illumination Illumination is an activity and should be subjected to RISK ASSESSMENT
CENTRAL ELECTRICITY AUTHORITY REGULATIONS, 201097. Lighting, overhead lines, communication and fire precautions.- In a mine illuminated by electricity, one or more flame safety lamps, or other lights approved by the inspector of mines, shall be maintained in a state of continuous illumination in all places where failure of the electric light at any time shall be prejudicial to safety. (4) In case of mines, minimum clearance above ground of the lowest conductor of over head lines or over head cables where dumpers or trackless vehicles are being operated shall not be less than twelve meters in height from the ground across the road where dumpers or trackless vehicles cross
Purpose of Illumination The Operator with the ability to see, especially at night and/or be aware of the people , vehicles, structures or other objects to ensure the safe and effective operation of the equipment to avoid collisionsProvide the ability for the operator to appropriately warn persons in the vicinity of equipment operationOptimise visibility of equipment to others operating in the vicinity
To avoid accidents due poor illuminationCollisionsSlip/trip/falls (ore dressing areas, drills , getting in and out of Machines, pump locations, confined spaces, nip points Falls of ground (drilling, loading, dumper placement close face/edge)Above all creating a safe environment GLARE IS PARTICULARLY AN ISSUE IN SAFETY. BRIGHT AND/OR BADLY SHIELDED LIGHTS AROUND ROADS UN EXPECTEDLY, MAY PARTIALLY BLIND DRIVERS OR PEDESTRIANS AND CONTRIBUTE TO ACCIDENTSWhy look at mine lighting?
A cat cannot see properly in ordinary day lightAnimals like tiger are hunted by focusing search light that blinds them by glare.They get confused and remain stay putHumans get partially blind by glare(egs) in marriage halls when light is focused Illumination does not mean merely fixing lights all around but placing lights judiciously to ensure that all areas where men or machine have access are clearly visible without glare or shadow,uniform all through within toleranceIllumination should therefore address maintenance , ore dressing and all supplementary facilities. Also areas where entry is prohibited should have visible warning systems
Even in the same locationFactors influencing illuminationType &size of fixturesSpacing& Height Condition of haul roadShadow and bright zones Age and vision of individuals Season Summer Frequent dust whirl wind, Winter(Fog), Rains (Glare)
Illumination does not have a fit forget or universal solution .It depends upon location of deposit like slope of hill,Production- no of benches, excavators Flat topography shallow( Dip within say 8 deg)Flat topography deep ( steeply dipping)Light absorbing characteristics of ore/waste(Mn Clay, phyllites)season rainy/summer/winterTherefore this cannot be a uniform format but need basedlay out. Even this would change as technology and efficiencylevel of fixtures change
In the case of mines flat bedded deposits on plain topography, light fixtures can be all around thus ensuring uniform illumination
Mining on hill top and slope
If lighting towers are high above they tend to leave shadow zones close to bench toe, unless supported by light from the other direction
Effect of Tower heightEgs our Tower lights in wagon loading yardsLot of shadow area beneath tower
Ref Prof N C Karmakar, Prof Y V Rao, M Aruna, Lighting Haul Roads in Surface Coal Mines A Design Based on Reflectance IMEJ ; Feb 2008Beyond certain height we loose the efficiency 8 -10 m is ideal
From pole take readings at regular intervals and draw contours with one fixture and then with both fixtures This will guide in locating the fixtures with respect to loading pointsFixture could be of low height say 6-8 m and portable. Generally 2x400watts Metal Haloids on each structure can take a face length 400m and maintain glare free illumination of 10 lux
Take readings at regular intervals in all benches with no other source of lighting , preferably on a new moon day This would vary in wet and dry ground conditions, dust, fog etcLuxmeter should be calibrated
Uniformity of light distribution (Uniformity Ratio)Good lighting is not only a matter of more light but is also a matter of its proper distribution. For example, a well-lit road surface is expected to appear evenly illuminated, with no apparent dark patches and glare. It is possible only when the distribution of light is more or less uniform across the length and breadth of haul road. Uniformity ratio of illuminance on a given plane is a measure of the variation of illuminance over it.
Age Effects on VisionYellowing of Lens (age in years)Degradation of lens decreases effective light level and effective contrast (due to scatter)Night vision decreases with ageSmaller pupilEye less able to adapt to light Cloudy eye lens
Loading pointsEven though illumination from excavator ,dumper reporting for load/ moving out after load would be there , they are neither constant nor consistent. Rather they could lead to distraction , glare etcLoading as far as possible should be only with external source of light. Dumpers that report should be either with parking light or low beam only
HEIGHT OF LUMINAIREThe height of Luminaire shall be the vertical distance from the ground directly below the centerline of the Luminaire to the lowest direct-light-emitting part of the Luminaire GLAREThe sensation produced by a bright source within the visual field that is sufficiently brighter than the level to which the eyes are adapted to cause annoyance, discomfort, or loss in visual performance and visibility.
Glare is particularly an issue in road safety, as bright and/or badly shielded lights around roads may partially blind drivers or pedestrians unexpectedly, and contribute to accidents. Caused by high contrast between light and dark areas, glare can also make it difficult for the human eye to adjust to the differences in brightness. Light shining into the eyes of pedestrians and drivers can obscure night vision.
Glare can be categorized into different types.Blinding glare describes effects such as that caused by staring into the Sun. It is completely blinding and leaves temporary or-permanent vision deficiencies.Disability glare describes effects such as being blinded by oncoming car lights, or light scattering in fog or in the eye, reducing contrast, as well as reflections from print and other dark areas that render them bright, with significant reduction in sight capabilities.
Discomfort glare does not typically cause a dangerous situation in itself, though it is annoying and irritating at best. It can potentially cause fatigue if experienced over extended periods.Glare can also result in reduced contrast, due to light scattering in the eye by excessive brightness, or to reflection of light from dark areas in the field of vision, with luminance similar to the background luminance. This kind of glare is a -particular instance of disability glare, called veiling glare.Glare is particularly an issue in road safety. as bright and/or badly shielded lights around roads may partially blind drivers or pedestrians unexpectedly, and contribute to accidents
Haul roadsOne in every three poles may be at just above tyre height. This would avoid glare while crossing of dumperIn case of medians growing of bushes avoids glare as also contain dustEven if Illumination is of best standard a dusty condition will reduce visibility levels
Fixtures on Haul roadsLocation of P