Road Lighting Calculations

LIGHTING ILLUMINATION CALCULATION ROAD LIGHTING

1.0

INTRODUCTION

This Document covers the basic calculations to calculate the distance between the street lighting poles.

2.0

GENERAL

Road lighting calculations are done as per the average illuminance or illuminance criteria on the road surface.

The lighting calculations are done based on Philips software (CalcuLuX Road Ver 7.6.2.0). These calculations are performed for Single Carriageway, using 250W HPSV Lamp SGP100 type. As per BS 13201-1 & 13201-2, considered design parameters are

Lave

≥ 1.0 cd/m2

(Lmin/Lave)

≥ 0.4

UL(Luminance)

≥ 0.5

TI(Glare)

< 15 %

SR(Surround

≥ 0.5

Ration)

CalcuLuX is used for investigating the visibility level of a target on the road surface. This software calculates the target luminance, background luminance and the threshold of that target. Illuminance levels, uniformity and glare values on the surface of the road. The calculations are performed by considering high Pressure sodium Luminaire designed SGP100 1xSON-TPP250W.

The road model considered here is: Road arrangement

: Single Carriageway

Road width

: 3.5 M

Number of lane

: 1

Spacing

: 19 M

Mounting height

:

8M

(The lighting pole shall be mounted on the side of the pipe rack not from the ground) Tilt angle

:

5 Deg

The average illuminance reflects the general luminance level at which the driver performs. At the low level of lighting used for road lighting, performance improves with luminance in terms of increasing contrast sensitivity, increasing visual acuity and amelioration of glare.

At the same time overall and longitudinal uniformity values are obtained between the recommendation values as given CIE-115 [2]. Luminaire spacing parameter affects the visibility level. When the necessary overall and longitudinal uniformity values are obtained, the sufficient visual conditions in the road lighting can be created with the longer spacing. As a result of this using less Luminaire and consuming less energy better lighting conditions can be attained.

3.0

ILLUMINATION LEVELS

As per the design basis for Road Lighting general Lux requirement is 5.

4.0

TYPICAL CALCULATIONS – ROAD LIGHTING

The calculations presented below show Summary, Luminaire Information (Including Polar and Cartesian diagram); detailed information about the calculation results (in textual table, graphical presentation), Overview of schemes.

Type of fixture considered

=

250W Watt Street Light Luminaire

Lumen Output of the Lamp (LL)

=

33200 lumens

Lux Required

=

5

Width of the road (W)

=

11.48 feet (3.5 M)

Height of the pole (H)

=

26.24 feet (8 M)

Coefficient of utilization (CU)

=

0.18

Lamp Lumen Depreciation Factor (LLD)

=

0.8

Luminaire dirt Depreciation Factor (LDD)

=

0.9

Luminaries Spacing

=

LL*CU*LLD*LDD Eh*W

=

(33200*0.18*0.9*0.8) (5*11.48)

=

5.0

75 feet (23 Meters)

RECOMMENDATIONS:

Based on Calculations spacing between Light poles

: 23 M

Based on Simulation report (Phillips Calculux 7.6.2.0) average Lux achieved is

: 6.7

Hence 19 Meter spacing between Light poles is recommended.

Note : 1 Candela/m2 = 1 Lumen/m2