Chicago starts replacing lights

Conversion to sodium vapor lights on Chicago’s residential streets started in 1974, at a cost of $10 million, and followed up with another $10 million program that converted streetlights on major thoroughfares to sodium vapor lights. In all, the city converted almost 173,000 lights to sodium vapor between 1974 and about 1977.

But while they drew some praise for driving the shadows from city streets, the orange lights always have had their critics. Tribune architecture critic Paul Gapp called the lights “a city-wide orange abomination,” and the local chapter of the American Institute of Architects and others crusaded against them, to no avail.

Since the large-scale adoption of sodium vapor lights in the United States and elsewhere, studies have been done showing that they can hamper police identification of suspects because they decrease people’s ability to tell one color from another, because they make everything look orange at night.

The city estimated in 1973 that converting to sodium vapor lights throughout the city would save about $125,000 a year in electricity and maintenance costs -- or about $635,000 in today’s dollars -- by converting about half its 182,500 lights to sodium vapor. Adjusted for inflation, that’s almost exactly how much the city hopes to save by converting just 16,000 lights this year.

The change also is estimated to decrease carbon dioxide emissions by about 15,000 metric tons a year, according to the Transportation Department.