TB Solution Given Data: Street width = 15 m, Mounting height = 7.5 m Lamp size = 6000 lumen, Luminaire type = II Coefficient of utilization = 0.44, Maintenance factor = 0.8 average Lux = 6 Explanation: The following relationship was used to determine of spacing between the lighting units: Spacing b/w lighting units = (Lamp size x Coefficient of utilization x Maintenance factor) / (Street width x average Lux) = (6000 x 0.44 x 0.8) / (15 x 6) = (2112) / (90) = 23.46 m Spacing b/w lighting units​ = 23.46 m Additional Information When the value of the coefficient of utilization is not given in the equation, we use the following graph & the ratio of road width and mounting height to determine the value of the coefficient of utilization. [ alt="F1 Killi 02-12-21 Savita D6" src="//storage.googleapis.com/tb-img/production/21/12/F1_Killi_02-12-21_Savita_D6.png" style="width: 406px; height: 285px;"> Figure: Graph b/w coefficient of utilization and ratio of road width and mounting height