alt Hacker NewsThe monochromatic light emitted from sodium lamps is also close to the peak sensitivity of the human eye. Colours are not distinguishable, but contrast is much enhanced compared to “cooler” light sources.
*edit: but it’s the overwhelmingly larger lifespan (20-30k hrs) that led to the wide adoption as streetlights. And I guess, the same is true for the change to led today, because of less power consumption.
Sodium lamps were deemed dangerous for driving” because they made it difficult for drivers to distinguish shapes, since they were different from day shapes. A kid in bright 1980ies colors (Little Red Hood) would look black under those lights.
LED was presented as a sharp improvement because of the large spectrum of white light.