Abstract
Low-pressure sodium lighting was installed on a mile-long stretch of Stevenson Expressway (Inter State 55 )Chicago Illinois, by the State of Illinois Department of Lightways. This article describes the design of the lighting systems which produced higher illumination levels than the mercury lights it replaced, at half the power consumption of the latter The results of a questionnaire issued to a population sample of 165 motorists shows a response highly in favour of the sodium lighting system.