October 6, 2014 1 Comment
Classification of Street:
|Classification Roadway Traffic|
|Classification Number||Number of Vehicles per Hour|
|Maximum Night Hour||Both Direction|
|Very light traffic||Under||150|
|Very heavy traffic||2400||4000|
|Classification of Pedestrian Traffic|
|Light or No Traffic||Residential, warehouse areas on express / elevated depressed roadways|
|Medium Traffic||Secondary business streets and some industrial roads|
|Heavy Traffic||Business streets.|
Mounting Height of Street Light Laminar:
- The distance the lamp is mounted above the roadway will affect the illumination intensity, uniformity of brightness, area covered, and relative glare of the unit.
- Higher mounted units will provide greater coverage, more uniformity, and reduction of glare, but a lower illumination level.
- It is necessary to weigh the effects of larger lamps against a greater number of smaller units at lower mounting heights with maximum glare potential.
- The height of luminaries above the roadway surface varies from 5 Meter to more than 20 Meter.
- Conventional roadway lighting utilized mounting height of 8 to 20 Meter. The lower mounting heights require the use of cutoff or semi-cutoff luminary’s distribution to minimize glare.
|Height of Pole||Application|
|6 Meter||For streets ,alleys, public gardens and parking lots|
|8 Meter||Urban traffic route, multiplicity of road junctions,|
|Narrow roads such as local access roads in residential areas in which a mounting height between 10 M or 12 M and 5 M or 6 M is required.|
|10 Meter||Urban traffic route, For wide heavily used routes where a large number of intersection, bends can lead to a short spacing making the use of 12 M mounting height uneconomical.|
|12 Meter||Wide or heavily used routes where advantage can be taken of a longer spacing of luminaries.|
|18 Meter and above||High mast lighting poles shall be installed at large-scale area such as airports, dockyards, large industrial areas, sports areas and road intersections|
|Type of Road||Pole||Pole Height||Laminar Watt||Type of Laminar|
|Rural||Aluminum or Steel Pole||10 to 16 Meter||250W to 400W||HPS|
|Urban||Aluminum||10 to 13 Meter||250W to 400W||HPS (Cut off or Semi Cut off)|
High Mast Lighting Systems:
- High mast lighting has 3 or 4 no’s of 1000 watt HPS luminaries mounted on poles /towers, at mounting heights (30 Meter). It develops a highly uniform light distribution.
- Excellent uniformity of illumination, reduce glare with a substantially smaller number of pole locations.
- Where continuous lighting is desirable such as lighting of toll plazas, rest areas ,parking areas, general area lighting, highways , traffic lanes.
- High mast lighting is also desirable where there is minimal residential area.
- High Mast used at remote location to eliminates the need for maintenance, vehicles obstructing traffic on the roadway.
- High Mast having symmetric or asymmetric distribution
- The design and installation of high mast lighting equipment is more complex than conventional lighting.
Correction Lamp Comparison Chart (Bureau of Energy Efficiency, Delhi)
|Lamp Type||Lamp ( Watts)||Efficacy (Lumens /Watt)||ColorRender
|Incandescent (GLF) Lamps:|
|(Incandescent bulbs)||15,25,40,60,75,100,150,200, 300,500 (no ballast)||8 to 17||100||1000|
|Tungsten Halogen||75,100,150,500,1000,2000 (no ballast)||13 to 25||100||2000|
|Fluorescent Tube lights(Argon filled)||20,40,65, (32,51,79)||31 to 58||67 to 77||5000|
|Fluorescent Tubular Lamp (T5)||18,20,36,40,58,65||100 to 120||Very Good||15,000 to 20,000||Energy-efficient,long lamp life,
only available in low wattages
|Compact Fluorescent Lamps (CFLs)||5,7,9,11,18,24,36||26 to 64||85||8000|
|High Pressure MercuryVapor (HPMV)||80,125,250,400,1000,2000||25 to 60||45 (Fair)||16,000 to 24,000||High energy use,Poor lamp life|
|High Pressure Metal Halide Lamps (HPMH)||70,150,250, 400,1000,2000||62 to 72||70 (Excellent)||8000 to 12000||High luminous efficacy, Poor lamp life|
|High Pressure SodiumVapor Lamps (HPSV)||70,150,250,400,1000||69 to 108||25 to 60 (Fair)||15000 to 24000||Energy-efficient, poor color rendering|
|Low Pressure Sodium Vapor Lamps (LPSV)||35,55,135||90 to 133||Very Poor||18000 to 24000||Energy-efficient, very poor color rendering|
|Low Pressure Mercury Fluorescent TubularLamps (T8 & T12)||35,55,135||30 to 90||Good||5000 to 10000||Poor lamp life, medium energy use, only available in low wattages|
|Light Emitting Diode (LED)||70 to 160||Good||40,000 to 90,000||High energy savings, low maintenance, long life, no mercury. High investment cost, nascent technology|