Will tunable street light breakthrough silence LED critics?

Major North American cities, including Montreal (pictured) and New York have abandoned plans to install 4000K LED street lights in light of advice from the American Medical Association.

What is thought to be the first successful deployment of white tunable connected street lighting is currently being tested in a suburb of St. Paul, Minnesota.

The system is, reportedly, able to regulate the amount of potentially unhealthy blue light that is emitted from street lighting.

The American Medical Association (AMA) sent shockwaves through the industry a few months ago by stating in a report that the blue light emitted from LED street-lighting could cause sleep problems as well as adverse risks when driving, guidelines the respected body has since officially adopted.

In response to the AMA report a number of major North American cities, including Montreal and New York have abandoned plans to install 4000K LED street lights and instead adopted 3000K street lights, a level prescribed by the AMA.

The new innovation, developed by Echelon, will allow city authorities to adjust the colour of street lights, changing their hue based upon the time of day, weather conditions and traffic events.

Dimming levels can also be adjusted, allowing city managers to turn up the levels of light during an emergency, for example, to assist first responders and emergency services with their work.

The system allows authorities to adjust both the light level and the white colour, allowing them to tune from warm white (2700K) all the way to cool white (5500K).

'The new technology could give us the power to elevate the level of public safety and quality of life across our entire community.'

Mark Burch, public works director in the St. Paul’s suburb of White Bear Lake

A warm white of 2700K has been found to be preferred for times with low activity, while a higher colour temperature of 4500K was deemed to provide better visibility for times with higher activity and during public events.

‘The new technology could give us the power to elevate the level of public safety and quality of life across our entire community,’ commented Mark Burch, public works director and city engineer, in the St. Paul’s suburb of White Bear Lake.

‘Cities now need not compromise safety for comfort or vice versa,’ Ron Sege, chairman and CEO of Echelon added. 'This new technology is paving the way for smart cities to improve quality of life, while still achieving energy efficiency and sustainability goals.’

The American Medical Association in their report last year, recommended that blue-rich LED lighting be controlled so as to limit glare on the road and discomfort.

The organisation also warned that blue-rich LED lights may suppress melatonin, having a negative effect on circadian rhythms, the body’s internal clock, prompting poor sleep quality. This in turn can lead to more serious health concerns such as obesity.

However, this does not mean LED lights are completely unsuited to the task of street lighting. The US Department of Energy stands enthusiastically behind them due to their energy slashing prowess and their ability to reduce a city’s overall maintenance bill.


  • Smart cities will be discussed in detail at this year's Lighting Fixture Design Conference. Mark Cooper of Smart City Advice will consider how manufacturers can best maximise the opportunities that the Smart City revolution offers. The event will be held in London on the 21 - 22 of February 2017 at the Cavendish Centre. You can find out more about the event here and you can register to attend by clicking here.

Comments 8

It won't change the fact that white lighting reduces night time vision by a considerable amount compared to yellow-orange.

Keep up the good work.

Eric Allen it is quite simply nonsense to consider a 4000k HID or Fluorescent the same as a typical 4000k LED in this application. ALL the long established peer reviewed research shows a typical 4000k source DOES NOT work as well in rain or fog and is significantly detrimental to older drivers and pedestrians alike response. Furthermore any 4000k source represents at best only a very marginal benefit in peripheral vision however the sharp cut-off of LED optics are showing some very strange results . Lack of peripheral awareness with current LED solutions is a very real phenomena and being reported by Young and old alike .Is is complex and needs further research but pole geometry and MH may be a factor. A lack of design function in implementation may also be a significant contributory factor. The panel that introduced the S/P adjustment here in the UK of which I was a member expressly noted that any potential gain for elder driver would be minimal and much further research would be very beneficial. In more traditional times new tech introductions would have advanced much more slowly enabling the glitches to be ironed out. Our breakneck speed of adoption is not affording the industry that luxury and there is still much to do. 4000k at first glance can appear excellent to observers but the effect of point source delivery can indeed throw up some very disorienting results in wet weather. Van Bommels work is an excellent source of information as is the 2015 research on the negative bad weather and glare impacts of a 4000k LED. Hope that's useful

I would like to add a clarification to my earlier post. Blue light has shown to have several adversarial effects. However, it is important to distinguish blue light hazard and blue light reducing melatonin during nighttime hours. Blue light hazard is the term that describes the photobiological damage to us. The damage is physical in the form of optical (retinal damage) and thermal (general physiological disruption). Thanks to Simon Nicholas for noting the mistake. Having corrected myself, LED or any other type of light that has a high blue content in the spectrum can cause sleep disruption and blue light hazard.

Extreme glare in inorganic LEDs come from primarily extremely high luminance of the LED chips. Glare increase due to high CCT is minute compared to the astounding contribution in glare that comes from astounding luminance in inorganic LED chips. This is explained for the first time in my book (Understanding LED Illumination, CRC Press, 2013 - it is an engineering and science text book). Unless IES, CIE, OSA, APS, and AMA members understand this effect, no current optics or reflectors out there is going to solve the LED glare problem. Currently the glare in LED luminaires is suppressed using thick translucent covers which doesn't solve the LED directionality problem; it only offers a scalar reduction in luminous intensity. Further luminous efficiency and efficacy are both substantially reduced by the usage of thick, translucent covers. Additional note of caution: although it is correct that blue light hazard disrupts sleep, AMA or RPI hasn't published their data on the amount of damage to our health due to over exposure of blue light content at night. Two notable presentations I have attended to from notable people and institutions unfortunately didn't even know the difference between total lumen and lumen density concepts; the other presentation from last year Lightfair on this subject showed data that were meaningless in terms of showing impossible signal response that cannot happen under any circumstance. My question regarding this was not answered even after the presentation when I asked for explanation of this nonsensical data. So folks, we have a lot of work to do to get this LED lighting right for illumination. Dr. M. NIsa Khan IEM LED Lighting

Why would any rational person choose to illuminate roadways with lighting designed to not interfere with sleep?? Driving safely requires full focus and alertness, not a relaxing sleep mode. There is certainly a time to be relaxed and able to sleep and IT IS NOT WHILE DRIVING. So perhaps those folks asserting that they know so much better than the rest of us should consider the whole situation before spreading their beliefs. The fact that the warmer shades of white are both less efficient and more expensive should also be considered when deciding which color temperatures of light to use. Has anybody considered the possibility of using colors of light other than white for roadway illumination? Have any experiments been done to see which colors might be better?

Having read the original AMA article and ALL the surrounding comments and responses, the 3000K/4000K difference is much ado about nothing. Outdoor lighting has been using 3000K or 4000K CCT in HID for decades with no co9mments or complaints other than its easier to see in a field illuminated with 4000K metal halide lamps than one illuminated with high pressure sodium lamps due to the better color rendition. The big flap about color and brightness has been a result of poorly designed outdoor LED optics that produce significantly harsher "glare zones". Early LED products used much higher CCT values such as 5000K and 6000K because earlier generation LED's produce higher light levels at these higher CCT values. Such luminaires looked terrible and very "blue" but even today's 4000K luminaires can look har4sh if they have poorly designed optics and a lower CCT value such as 3000K will look softer to the eyes. In my opinion, the author of the AMA article probably came home one night to find his street lights had been changed and he didn't like the new look, thus the disparaging article. While sympathetic to the aesthetics, I promise the doctor to never make a medical diagnosis if he promises to exhort his township to hire a lighting professional to select the community's luminaires rather than buy the cheapest ones available

Give it 5 years. Right now tuneable White is 30% less efficient on terms of lumens per watt and 50% more expensive. Plus the cost of controls....

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