Jake Ford – 2011
Why Street Lighting?
The increasing reliability and availability of autonomous vehicular technology is creating a critical mass of interest and development, two decades after the start of the twenty-first century. Estimates place the first commercially available autonomous vehicles on the market between 2017 and 2020, while some of these features are currently in use on roads at the time of writing.(Google) The widespread adoption of this technology has the potential for wide-reaching impact on our cities, and the infrastructures which cater to currently modes of automobile traffic. Secondary and tertiary infrastructures to the actual roadway – sewer grates built into road curbs, highway off ramps, rest stops, gas stations, street lighting, stop signs amongst many others – stand to undergo significant change in the coming decades, as demands on road infrastructure center on the autonomous vehicle. Infrastructure and Urban Design, at this point, perhaps more than any other in the history of the automobile, have the power to envision and re-envision the way our road infrastructure operates. Even infrastructural systems which have been in place for decades; have seemingly little to do with whether a vehicle can drive itself or not have the potential for positive change, as we reevaluate it in this new urban context. Street lighting is one such infrastructure.
Street lighting conditions are dictated almost exclusively by the visibility needs of the automobile’s driver, though their impact is felt by pedestrians, nearby buildings, and surrounding wildlife. Minimum light levels are determined based on stopping distances, drivers’ reaction times, and the light level at head height requirement – meant to identify pedestrians. (Lighting Handbook) Urban street light conditions are essentially the product of the ability to see crossing pedestrians and this relationship will be disrupted by autonomous vehicles, which likely will not require the same lighting conditions to function safely and effectively.
Lighting Reduction is a Big Goal
Despite this rather singular focus, street lighting has an effect felt far beyond the roadbed. The inefficiencies of top-down road lighting generate excess light which enters the surroundings as light pollution – unwanted or excess light – filtering into bushes, trees, apartments, the night sky. There is an inherent waste of energy in providing a constant excess of light across a streetscape which only needs to accommodate traffic a fraction of the time. The City of Detroit has is currently in the process of a street lighting renaissance; a 200 million dollar public works project, which is replacing existing (and outdated) high-pressure sodium lamps with high output LEDs, resulting in a projected reduction of $16.6M off of the current $20M annual energy expense, an 83% reduction in energy costs. (Millard) As artificial lighting accounts for 19% of global energy expenses, there is a compelling case in addressing carbon emissions and expenses.(Hölker et. al.)
There is a clear economic case for a lighting infrastructure overhaul, but the detriment of overhead lighting extends into the physiological realm – light pollution has potentially wide-reaching negative impacts on urban dwellers as well as light-sensitive animal species. (Hölker et. al.) The effects of unwanted light have an ill-understood effect on human health as studies in the area are lacking, but physiological processes like sleep cycles rely heavily on light levels for regulation, and the long-term presence of light pollution has “psycho-physiological” implications.(Hölker et. al.) As levels of artificial light around the world increase by 6% year over year, the effects on ecology and human wellness will quickly compound.(Hölker et. al.) There are emerging, and urgent physiological reasons to reexamine the current urban lighting paradigm.
A blanket reduction in light levels across the city seems a no-brainer: improved sleep patterns, improved ecological wellness, reduced greenhouse emissions, reduced costs, yet there are other psychological concerns to take into consideration. Much literature on the subject of urban lighting is dedicated to safety, and feelings of safety. However, there are contradictory claims in either direction about the efficacy of lighting, despite the feelings of safety that are determined to be fostered by certain lighting conditions.(Harnik et. al.) It is possible that a reduction in lighting yields an increase in safety, while decreasing feelings of safety.(Harnik et. al.) Lighting infrastructure in the age of the autonomous vehicle should strive for an overall reduction in light levels redesign should focus on an overall reduction of light levels, and attitudes toward safety will adapt if the design is sufficient.
Street-lighting need not be omnipresent. The largest problems with street lighting, ironically, in striving to meet minimum levels of illumination on the road bed, excess light is created and dispersed. Overhead street lighting is the biggest contributor to this end – it is highly inefficient toward the goal of directing useful light towards the road.
