ppvora from Downingtown, PA on 8/8/2019 8:17:11 AM:
I was on the towpath from Little Orleans, MD to Harper's Ferry, WV and back toward the end of July this year. There were two instances where we had to lift our bikes and carry them up and down staircases: (1) In Williamsport MD, they are repairing the towpath and there's a detour in town over a wooden bridge. The wooden bridge has a rail on the side on which one can ride their bike up and down -- you have to angle it so that the pedals don't strike the rail. (2) In Harper's Ferry to cross the river one has to go up the bridge on the Maryland side but on the WV side there's a ramp for rolling your bike.
Neither bridge was too challenging. However, although we had heavy bikes, our panniers were pretty small and light. I saw bikers on the towpath with some serious panniers attached to their bikes that appeared to be laden with a lot of stuff. I'm guessing they would have to unhitch the panniers off the bikes and carry the bike and the panniers up separately.
In our case, we took at most 10 minutes on the bridges, so it wasn't challenging at all.