became the first utility in the US to use induction fluorescent lamps to replace mercury vapor lamps, in 220 municipalities. The induction lamps were expected to last 100,000 hours before requiring maintenance and consume 30 to 40 percent less electricity, thereby saving an estimated $1 million annually. The induction lamps also provide a whiter light, and contain less mercury. Following extensive field tests, the City of San Diego decided in 2010 to replace 10,000 of its high-pressure sodium (HPS) streetlights with cobra-head induction luminaires. Astronomers from the nearby Palomar Observatory had objected to replacing the HPS lamps with light sources with higher color temperatures, which would increase light pollution and interfere with their research. One of the key findings of the field assessment was that LED luminaires became more expensive and less efficient at lower color temperatures. The City of San Diego has standardized on induction lighting for street lights, but uses low-pressure sodium (LPS) lamps within a 30-mile radius of the observatory. Urban Light Urban Light at the entrance to the Los Angeles County Museum of Art (LACMA) Center, Los Angeles, is an assemblage of historical street lights taken from actual usage in Southern California in the form of a 2008 sculpture by Chris Burden. See also Bartlett street lamp Gas lighting Intelligent street lighting Light pollution Light fixture Street lighting in the District of Columbia Further reading References History of science and technology in the United States Street lighting