Blue DOT Signs

[TommyBNSF]

Does anyone know when these blue ENS signs became mandatory ? I've been noticing these pop up on just about every railroad now, even NS and CSX who used white signs before.

[freebrickproductions]

From what I've heard (which was over Facebook, so it could be wrong, especially since my recollection of it is fuzzy at best) all railroads with a 1-800 number have to have them by sometime 2017. It's the design in the 2009 MUTCD so the FRA decided to regulate it, I guess.
You can see it here (section 8B.18):
http://mutcd.fhwa.dot.gov/pdfs/2009/part8.pdf

[TommyBNSF]

And while on the subject, NS and UP make no sense with how they turn their signs sideways. You can tell in the video below that they're not easily readable in the car if the crossing is malfunctioning (trust me, I've had to call the number on the DOT sign before). Seriously NS and UP, what the heck are you thinking?

https://www.youtube.com/watch?v=KeUZDZG8Tj0