Evaluation and design of road lighting

Need To enable road users to see the carriageway and immediate surroundings in darkness Causes of road accidents Headlight driving insufficient, glare problem, accidents Hence, the need to illuminate the carriageway

Mounting height High mounting reduces glare Uniform luminance Costlier Mountings of 7.5 – 12 m for traffic routes and 3 – 8 m for other streets More powerful the lamp, increased mounting height, to reduce the glare

Spacing Not to exceed 55 m Preferably 35 – 45 m on important traffic routes Spacing should be between 3 and 5 times the mounting height

Lantern arrangements Single sided Staggered Central Opposite

Quantity of illumination needed on different streets Recommended average illumination (lumens/sq. m)

Average illumination of streets in lumens / sq. m = ((lamp lumens) * (coefficient of utilization) * (lantern maintenance factor)) / ((spacing between lanterns in m) * (width of roadway in m))

Lamp installation at T junctions and cross roads Lantern is located in the major road, just beyond the entrance from the side road, to indicate the driver on the side road that he is approaching a T junction

Cross - roads

Traffic Rotaries Lantern A – above the curb of central island Lantern B – above each section of the outer curb of the rotary Lantern C – provided when pedestrians cross the channelising island