EEE World, Department of EEE, ADBU: How to Design efficient Street lighting-(Part-1)

Introduction:

The basic idea of roadway and Highway lighting is to provide uniform level of illumination on road at horizontal and vertical level and provide a safe and comfortable environment for the night time driver.
Lighting design is basic idea of the selection and the location of lighting equipment to provide improved visibility and increased safety.
Street lighting systems should be designed in a way to avoid significant differences in luminance levels at the light source and on road areas. Furthermore, continuous variation of lighting levels can cause eye strain and should be avoided, in particular on long roads.
Road lighting provides visual conditions for safe, quick and comfortable movement of Road users.

(A) Type of Road

(B) Street Light Pole

(C) Lighting Fixture

(D) Lighting Factors

(E) Lighting Uniformity

(F) Lighting Pollution

(G) Selection of Luminas

Table 4 : Road Classes as per SP 72 (Part 8), IS 1944 (Part 1) and IS 1970
Class A1	Important routes with rapid and dense traffic where safety, traffic speed, and driving comfort are the main considerations
Class A2	Main Roads with considerable volume of mixed traffic, such as main city streets, arterial roads and thoroughfares.
Class B1	Secondary roads with considerable traffic such as main local traffic routes, shopping streets
Class B2	Secondary roads, with light traffic
Class C	Lighting for residential and unclassified roads not included in previous groups
Class D	Lighting for bridges and flyovers
Class E	Lighting for town and city centers
Class F	Lighting for roads with special requirement such as roads near air fields, railways and docks

TYPE OF ROAD
TYPE OF ROAD	DENSITY OF TRAFFIC	TYPE	EXAMPLE
A	Heavy and high speed motorized traffic	Road with fixed separators, No crossings for very long distance	National highways or state highways or called interstate highways, express ways or motor ways
B	Slightly lower density and lower speed traffic termed	Road which is made for vehicular traffic with adjoining streets for slow traffic and pedestrians as we find in metros	Trunk road or major road in a city
C	Heavy and moderate speed traffic	Important urban roads or rural roads. they do not interfere with the local traffic within the town	Ring roads
D	Slow traffic, pedestrians	Linking to shopping areas and invariably the pedestrians, approach road	Shopping street, trunk road
E	Limited speed. Slow or mixed traffic predominantly pedestrians,		Local streets, collectors road

There are four basic types of street lighting layout arrangements used for streets or highways illumination.

(A) One Side Pole Layout:

In One Side Pole Layout, all luminaries are located on one side of the road.
Road Width: For narrower roads.
Pole Height: The installation height of the lamp be equal to or less than the effective width of the road surface.

Advantage: There are good indelibility and low manufacturing cost.
Disadvantage: The brightness (illuminance) of the road on the side where the lamp is not placed is lower than the on which side the light pole is placed.

(B) Both Side Staggered Pole Layout:

In the staggered arrangement, the luminaires are placed alternately on each side of the road in a “zig-zag” or staggered fashion.
Road Width: For Medium Size roads.
Pole Height: The installation height of the lamp is equal or 1.5 time the effective width of the road.

Advantage: This type of arrangement is better than single side arrangement.
Disadvantage: Their longitudinal luminance uniformity is generally low and creates an alternating pattern of bright and dark patches. However, during wet weather they cover the whole road better than single-side arrangements.

(C) Both Side opposite Pole Layout:

In Both Side Opposite Pole Layout, the luminaries located on both sides of the road opposite to one another.
Road Width: For Medium Size roads.
Pole Height: The installation height of the lamp will be 2 to 2.5 time the effective width of the road.

Advantage: opposite arrangements may provide slightly better lighting under wet conditions.
Disadvantage:
If the arrangement is used for a dual carriageway with a central reserve of at least one-third the carriageway with, or if the central reserve includes other significant visual obstructions (such as trees or screens), it effectively becomes two single-sided arrangements and must be treated as such.

(D) Twin-central Pole Layout:

In Twin central arrangement, the luminaries are mounted on a T-shaped in the middle of the center island of the road. The central reserve is not too wide, both luminaires can contribute to the luminance of the road surface on either lane.
Road Width: For Large Size roads.
Pole Height: The installation height of the lamp be equal to the effective width of the road.

Advantage: This arrangement generally more efficient than opposite arrangements. However, opposite arrangements may provide slightly better lighting under wet conditions.
Disadvantage: