Flange Way Signs

What was the purpose of “flange way signs” on real railroads?

To warn the roadmaster or snowplow operator to lift the blade on the flanger, spreader, or snowplow above top-of-rail before it collides with a turnout, at-grade crossing planks, diamond, dragging-equipment detector, or flange lubricator, and ripping it out, damaging the flanger, or both. A good way to get fired if you’re not paying attention and don’t lift the blades in time.

RWM