For those of us who grew up in cities, street lights have always been a part of our lives. Truth be told, we never really think much about it until we stumble across an area that is either too dark or too bright. Yes, most people take street lighting for granted even though humans (like some bugs) are naturally attracted to light.
In the early civilisations, light primarily serves the purpose of security, both to protect the wanderer from tripping or keeping potential robbers at bay. Today, street lighting also serves to facilitate traffic flow, promotes the use of public facilities during the night hours and much more.
Governments around the world spend a considerable amount to maintain street lights along public roads to keep us safe and secure. If you are a tax-payer, it is your right to have sufficient lighting and you can provide feedback to your respective authorities otherwise. It is also our right to be taxed so we might as well make full use of our tax-paying priviledge.
Generally, governments engage term contractors to maintain street lights. One of their activities is to ensure that roadway lighting is uniform. Lighting uniformity is represented by U0 and it is given to us by taking the ratio of the minimum illuminance, Emin, to the average illuminance, Eaverage, i.e., Emin / Eaverage. So how does this all work in real life?
Before Cosmiqo, technicians hired by term contractors would carry out measurements by hand (They still do but much less now). This would involve the rather dangerous task of having to find the darkest spot - typically between two street lamps of choice - followed by nine other evenly distributed points on a lane to find the average (see Figure 1). Now repeat this for every lane across every road. One can only wonder how much time it will take to completion.
Because of this, illuminance measurements are carried out in the wee hours of the morning to reduce the risk of accidents but probabilities are still high. The next time you see someone standing in the middle of the road, do be careful. He could be performing illuminance measurements to ensure our public roads are safe and secure, for us.
On to Part 2 of 3.