Editing Traffic light (section)

=== Bulbs ===
Conventional traffic signal lighting, still common in some areas, uses a standard light bulb. The light then bounces off a mirrored glass or polished aluminium reflector bowl, and out through a polycarbonate plastic or glass signal lens. In some signals, these lenses were cut to include a specific refracting pattern. Traditionally, incandescent and halogen bulbs were used. Because of the low efficiency of light output and a single point of failure (filament burnout), some traffic authorities are choosing to retrofit traffic signals with [[Light-emitting diode|LED]] arrays that consume less power, have increased light output, and last significantly longer.{{Citation needed|date=July 2020}} 

In the event of an individual LED failure, the aspect will still operate albeit with a reduced light output. The light pattern of an LED array can be comparable to the pattern of an incandescent or halogen bulb fitted with a [[prismatic lens]].

The low energy consumption of LED lights can pose a driving risk in some areas during winter. Unlike incandescent and halogen bulbs, which generally get hot enough to melt away any snow that may settle on individual lights, LED displays&nbsp;– using only a fraction of the energy&nbsp;– remain too cool for this to happen.<ref>{{cite web |url=http://www.ctv.ca/CTVNews/Canada/20100110/LED_Snow_100110/ |title=LED traffic lights could pose winter driving risk |publisher=CTV |date=5 October 2011 |access-date=5 October 2011}}{{dead link|date=July 2021|bot=medic}}{{cbignore|bot=medic}}</ref><ref>{{cite web|url=https://abcnews.go.com/GMA/ConsumerNews/led-traffic-lights-unusual-potentially-deadly-winter-problem/story?id=9506449|title=LED Traffic Lights Unusual, Potentially Deadly Winter Problem |author=Elizabeth Leamy |author2=Vanessa Weber |date=4 January 2010 |work=ABC News}}</ref> As a response to the safety concerns, a heating element on the lens was developed.<ref>{{cite web |author=Marmarelli, Beth |title=Engineering Team Develops Device to Aid LED Traffic Signals in Inclement Weather & Places Overall in Campus's Senior Design Competition |publisher=University of Michigan |date=22 June 2011 |url=http://sustainability.umich.edu/news/engineering-team-develops-device-aid-led-traffic-signals-inclement-weather-places-overall-campu |access-date=22 June 2011 |archive-date=13 April 2012 |archive-url=https://web.archive.org/web/20120413011756/http://sustainability.umich.edu/news/engineering-team-develops-device-aid-led-traffic-signals-inclement-weather-places-overall-campu |url-status=dead }}</ref><ref>{{cite web |url=http://www.faqs.org/patents/app/20120255942 |publisher=United States Patent Office |title=Patent application title: Traffic Light Heater |work=Class name: Heating devices combined with diverse-type art device electrical devices, 20120255942 |author=Hankscraft Inc. |date=11 October 2012 | access-date=11 October 2012}}</ref>