in this ppt i discussed about street lighting, why it is used, what are the factors affecting the street lighting.

1. DR. S. & S.S GHANDHY GOVERNMENT
ENGINEERING COLLEGE
Traffic Engineering (2170613)
TOPIC :- Street lighting
SEMESTER :- 7
PREPARED BY:-
Chelani Prashant (160230106010)
Patil Nikhil (160230106043)
Patoliya nisarg (160230106044)
Vadher vijay (160230106057)
Hazratwali samsor (160230106064)

2. Contents
• Need for street lighting
• Factors affecting night visibility
• Definitions
• Distribution of light
• Design factors for street lighting
• Design of street lighting systems
• Type of light sources
• Fundamental factors of night vision

3. Need for street lighting
• To enable road users to
see carriageway in darkness
• Road accidents – night and
poor lighting
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4. • To illuminate the carriageway in city streets
• To improve visibility in night
• Highway lighting – intersection,
bridge site, level crossing
• Urban roads – population high
road lighting advantage
• Rural roads – population less
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5. Factors affecting night visibility
2.Size of object
1.Amount and distribution of
light flux from the lamps

6. 3.Brightness of object
and background
4.Reflecting characteristics of
the pavement surface
5.Glare on the eyes of the driver 6.Time available to see an object

7. Definitions
1. Liminious flux (Φ) – radiant power given by light source
2.Lumen (lm) – SI unit of Liminious flux.
Lumen = candle power x solid angle
3. Steradian – measure of solid angle = ω
4. Luminous intensity (I) – flux per unit solid angle I =
Φ
ω
5. Candela – is called candle power
6. Metre candle – illumination produced – unit candle power – 1 m
7 illumination :- Amount of light flux which falls on surface
E =
Φ
A

8. 8. Luminance : intensity emitted per unit area B =
I
A
9. Glare – discomfort to see objects – due extreme contrasts in space
10. Luminare – House for one or more lamp –body & reflector
Beam
[lm]
Luminositiy
[lx = lm/m²]
Luminous intensitiy
[cd]
Brightness
[cd/m²]

10. Distribution of light
• Allowed to distribute radially from the source
• Good amount of flux required at a particular vertical angle
• Distribution of luminance is known as Glare
• Glare can cause discomfort and reduce visibility
Glare depends on :-
1. Brightness of glare source
2. Angle of incidence with respect to normal line of vision
3. Area of glare source

11. • Glare may be controlled by
1. Increasing the height of
mountings
2. Shielding the light source
3. Reduce the brightness
contrast of the light source
• Vertical distribution of light
3 types
1. Cut-off (> 70o)
2. Non-cut-off (High angle)
(80o)
3. Semi-cut off(75o)

12. Lateral distribution of light
• It is known as horizontal distribution of light
• Pedestrian footways and kerbs are equally lighted.
• 3 types
1. Symmetrical distribution
2. Axial distribution
3. Non-axial distribution

13. Design factors for street lighting
1. Contrast
2. Glare
3. Lamps
4. Luminaire distribution of light
5. Lateral placement of lighting poles
6. Height and overhang of mounting
7. Spacing of lighting units
8. Lighting layouts

14. Contrast
• Silhouette
• Discrimination of differences of
brightness between Object-Background
• Brightness of object < Brightness of
background = silhouette
• Object appears darker than road
Reverse silhouette
• Brightness of object > Brightness of
background = Reverse silhouette
• Object appears above the pavement
surface

15. Glare
Viewing visual task under low brightness
Types of glare – (i) Disability glare
-physiological
(ii) Discomfort glare
-psychological

16. Lamps
• Four types
1.Tungsten filament lamps
2.Sodium vapour lamps
3.Mercury lamps
4. Fluorescent lamps

17. Luminaire distribution of light
• It should cover pavement between kerbs
• It should produce maximum uniformity of pavement brightness
• 30 lux = Important roads having fast traffic
• 15 lux = other main roads

18. Lateral placement of lighting poles
• It should not installed very close to
pavement edge
a) For roads with raised kerbs = 0.3m
from edge (desirable=0.6m)
b) For roads without raised kerbs =
1.5m from edge

19. • Glare decrease with increase height of mounting
• Height ranges from 6 to 10m
Height and overhang of mounting
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20. Spacing of lighting units
• Spacing between lamps on roads = 3 to 5 times mounting height
• Sharp curves = spacing is closer

21. Lighting layouts
1. Single side lighting
- Economical for narrow roads

22. 2.Both side lighting – opposite

23. 3. Both side lighting – staggered
4.Central lighting
All lighting layouts

24. References
• http://toolkit.irap.org/default.asp?page=treatment&id=58
• https://en.wikipedia.org/wiki/Street_light
• https://www.ledil.com/application-areas/street-lighting/
• https://www.slideshare.net/YashPatel61/street-lighting-66220750
• Traffic Engineering and Transport Planning by L.R. Kadiyali, Khanna
Publishers, Delhi

25. Thank you