High-mast lighting

While most high-mast lights are high-pressure sodium, other lamp types such as mercury vapor, metal halide and LED, have also been used.

[2] [1] Maintenance of these systems is done by lowering the luminaire ring from the mast head to the base using a winch and motor to the ground or at a height accessible by a cherry picker and located in areas to allow for easier access without disrupting traffic.

That same year, TTI and the Texas Highway Department installed twenty 100 ft (30 m) high-mast lighting towers at two adjacent interchanges on Loop 410 on the northeast side of San Antonio as part of a study to evaluate the benefits and techniques of various types of highway lighting.

Participants in the San Antonio Illumination Study traveled through the study corridor multiple times over two nights to observe and report impressions of the lighting, after which they were asked to complete a questionnaire about their experience and rate the different types of lighting.

1968 saw the first permanent US installations of high-mast illumination starting in Auburn, Washington south of Seattle.