Alpe du Zwift Turn Colour Codes

The map window that shows Alep Du Zwift turns has some turn colour coded.

Red Numbers, Orange Numbers, Yellow Numbers, see screenshot below.

What do these colours indicate?

Gradient? Early sections are steep…so Red…and so on. That would be my WAG.

I was thinking more in the lines of personal records per segment?

They’re related to the difficulty of each segment, somebody from Zwift staff answered this in an old forum post from April 2018, but I’m not allowed to post links here

IIRC 3-6% is yellow; 7-8% is orange; and 9% and up is red. It’s giving you the average gradient for each of the turns so you can pace your effort

Thank you.