Again, just curious.
I think that’s a question to PD but I’m inclined to say not.
In the motion that allowed them to be built it says:
“When completed this great work will increase income of farms and businesses in the territories which the road network passes through.”
So no, they just boost farms and businesses in those territories.
Not even sure that Great Works can help armies move faster, think you can only do that by changing the armies special quality to fast, or possibly some sort of big ritual.
Thanks for the replies!