High Pressure sodium lighting produces a yellowish orange light color and is used in many street light and parking lot lights
The high pressure sodium lights have a relatively long life cycle at 20,000 rated hours.
When the high pressure sodium lights get older they tend to frequently flash on and off. Contrary to many reports this does not indicate that the fixture's ballast needs to be replaced.
The negative aspect of high pressure sodium lights is their overall color quality of the yellow/orange color as seen below and very low light quality - color rendering index of approximately 20.