No long time no see guys :)
I think I brought the idea up some years ago, I'm glad to see it visualized now, nice graphics!
I agree with the 2 (maybe 3) fields limit, after all it's a major shortcut at times and you want to keep seafaring necessary, right?
But how does the construction work, will the builder only work from one end? That was a question to me when I thought about it the first time already, I think it would look a little weird.
Bombarding with catapults would make for a cool interplay I think, but the point with the farm/mines is a good one ;)
I hope this will be discussed further!
I'm still following RTTR and I'm happy about the progress made through the years!