Today, street lighting commonly usesĀ high-intensity discharge lamps.Ā Low-pressure sodium lamps became commonplace after World War II for their low power consumption and long life. Late in the 20th century HPSĀ high pressure sodium lampsĀ were preferred, taking further the same virtues.Ā Such lamps provide the greatest amount ofĀ photopicĀ illumination for the least consumption of electricity. However, white light sources have been shown to double driver peripheral vision and improve driver brake reaction time by at least 25%; to enable pedestrians to better detect pavement trip hazardsĀ and to facilitate visual appraisals of other people associated with interpersonal judgements. Studies comparing metal halide and high-pressure sodium lamps have shown that at equal photopic light levels, a street scene illuminated at night by aĀ metal halide lightingĀ system was reliably seen as brighter and safer than the same scene illuminated by a high pressure sodium system.
Two national standards now allow for variation in illuminance when using lamps ofĀ different spectra. In Australia, HPS lamp performance needs to be reduced by a minimum value of 75%. In the UK, illuminances are reduced with higher values S/P ratio
New street lighting technologies, such asĀ LEDĀ orĀ induction lights, emit a white light that provides high levels ofĀ scotopic lumensĀ allowing street lights with lower wattages and lower photopic lumens to replace existing street lights. However, there have been no formal specifications written around Photopic/Scotopic adjustments for different types of light sources, causing many municipalities and street departments to hold back on implementation of these new technologies until the standards are updated. Eastbourne in East Sussex UK is currently undergoing a project to see 6000 of its street lights converted to LED and will be closely followed by Hastings in early 2014.
Milan, Italy, is the first major city to have entirely switched to LED lighting.
In North America, the city ofĀ MississaugaĀ (Canada) was one of the first and biggest LED conversion projects with over 46,000 lights converted to LED technology between 2012 and 2014. It is also one of the first cities in North America to useĀ Smart CityĀ technology to control the lights.Ā DimOnOff, a company based inĀ Quebec City, was chosen as a Smart City partner for this project.
Photovoltaic-powered LED luminairesĀ are gaining wider acceptance. Preliminary field tests show that some LED luminaires are energy-efficient and perform well in testing environments.
In 2007, the Civil Twilight Collective created a variant of the conventional LED streetlight, namely the Lunar-resonant streetlight.Ā These lights increase or decrease the intensity of the streetlight according to theĀ lunarĀ light. This streetlight design thus reduces energy consumption as well as light pollution.