The Science Behind Street Lighting
Lighting roads, whether it's a side street or a main highway takes a lot more preparation than most people imagine. While it’s easy to think that erecting a lamppost and facing the light down to do the job, things such as beam angle, lumen output, light temperature, and CRI all need to be taken into consideration. After all, street lighting’s only purpose is to provide adequate lighting that is conducive to keeping driver’s safe on the road.
The first thing that needs to be addressed is the arrangement of the lights, most government guidelines and standards will utilize one of four arrangement types. The first being a one sided layout, in which all lamp posts are on one side whose beams create enough lumens to illuminate the entire road from one side. Followed by a staggered arrangement in which there is one lamppost on each side of the street in a zigzag pattern.
An opposite-styled arrangement is used for the third option, in which a lamppost is placed directly opposite each other, illuminating their respective sides of the road. This however is the least used option as it typically tends to be the most costly option. On the other hand the most common arrangement used is the centered arrangement, in which the lamppost is erected between the two lanes with a one lamp angled on one side of the road, and one lamp angled to the other side of the road.
Once that has been addressed, attention then needs to be focused on the types of bulbs being used, their color temperature, total lumen output, and CRI. Within the context of lighting up a road the Color Rendering Index doesn’t play that big of a role, and a standard CRI of 80 will suffice. Most countries have now specified that they will only use LED bulbs for their street lighting due to its energy efficiency and durability.
In terms of color temperature 3000k and below will do the job, as it will be bright enough to adequately illuminate the road for the drivers, but not too bright where it could be a distraction for the drivers. Commercial billboards also have to adhere to these principles. Once the arrangement, beam angles, and color temperature have been decided, installation can begin which will be very straightforward as the lights will be installed into the lamppost, and will serve as one component installed into the ground.