Here in Vancouver, we have a greenway stretch too. It's shared by peds, cyclists, skateboarders and roller bladers. Not sure how yours is designed. However the greenway that we have is built under the guiderails of a MRT system. So along the way there are huge columns rising in b/t the greenway which causes blind spots despite the greenway is mostly straight.
I can imagine a dog walker hidden behind one of these columns because little Rex wants to take a piss. Then emerging suddenly out of the column while a cyclists may be bombing down the greenway at high speed. KABLAM! Little rex gets runned over and cyclist get road rash. It can happen.
There's a discussion on this now amongst the greenway users blog.